Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Ray on November 15, 2012, 03:26:40 am
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Just a couple of years ago I was considering upgrading from the Canon 50D to a 7D or 60D, mainly because of the video capability which none the DSLRs I owned at that time had.
However, when I saw the DR specs of the D7000 on the DXOMark website, I got very interested in that camera despite the fact that, at that time, I owned only one Nikkor lens, the 14-24/2.8 ultra-wide-angle zoom.
After some discussions on LL about the significance of shot noise at such low signal levels (some posters on LL seemed to think that any DR claims beyond about 12 stops for a small sensor would be an irrelevancy because shot noise would unavoidably mask any benefits), I took the plunge and bought a D7000 with Nikkor 24-120/F4 zoom.
After comparing the DR of my new D7000 with that of my Canon cameras, such as the 50D and the full-frame 5D, it became very apparent that the claimed 2-stop DR advantage of the D7000 was very real and only slightly obscured by the proportional increase in shot noise. I was very pleased with the camera's performance in general and would often marvel at how miraculously an almost totally dark image, underexposed at ISO 100 instead of properly exposed at ISO 6400, would spring to life with just a click on the 'auto' button in ACR.
The main attraction of the D800E for me was its incorporation into a larger sensor of all the qualities of the D7000. If fact, at equal image size, the D800E has about 1/2 a stop greater DR than the D7000, due to its larger sensor. However, I haven't taken the trouble to compare the DR of both cameras. I'm too busy enjoying photographing the real world.
It was while photographing the real world recently, in Thailand, I made the mistake of taking a shot at 1/60th, F8 and ISO 100 in manual mode, in near darkness at the end of the day, not realising the D800E's built-in flash was not still popped up. The review image was totally black. Not even a hint of a highlight. I didn't delete it due to laziness and the fact I was in a hurry to get back to the hotel before it got completely dark.
After downloading the day's images onto my Dell Notebook, and deleting a few mistakes and duds, I was about to delete the totally black preview in Bridge, of the F8 shot at 1/60th without flash, when curiosity got the better of me, and I decided to see just how noisy and awful this image really was.
When the image opened in ACR, the histogram showed just a single, thin, vertical line on the far left. There was absolutely no other information. Not even a little hump or two on the horizontal axis. Refer attached image.
However, after some extreme adjustments in ACR, such as +4 exposure, +100 Brightness, 100 Fill Light, +100 Darks in the Tone Curve etc, the image looked almost presentable, apart from an over all green cast. A single click on 'AutoColor' in Photoshop fixed that.
I'm just flabbergasted that so much detail actually exists in a shot I was about to delete. The purpose of the shot was to attempt to give a perspective on the actual size of this "Night Butterfly" (as it is locally known). I'd taken a few shots close up, with 24-120 zoom at 120mm, using the built-in flash, and as I was leaving the scene, still amazed at the enormous size of this butterfly, I decided to take a shot from a greater distance, hoping it would give a better impression of its great size.
Of course, "Night Butterfly" sounds more romantic than bloody Moth. But a check on the internet reveals it is in fact a moth, but the largest moth in the world, that goes by the name of Attacus Atlas. It's total wing surface area can be in excess of 62 sq inches (or 400 sq cm), and wing span in excess of 10". It's larger than my notebook on which I've processed the attached images. ;D
I've also shown a close-up of the moth taken when the flash was popped up. I thought it would immediately fly away, but it just twitched. I began to think it was maybe supremely confident because it had two snakes attached to its wings. It also had simulated patches of bamboo leaf on its wings as extra camouflage protection. Refer image 04, which I think is also rather abstract. If you think that detail is moire, don't hesitate to say so. ;D
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That is pretty amazing. The absence of horrible noise in the OOF areas is remarkable!!!
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That is pretty amazing. The absence of horrible noise in the OOF areas is remarkable!!!
Forgot to mention, I applied no noise reduction or masking in ACR. Sharpening was at a default level of 25.
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I'm impressed to say the least!
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That's insane!
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However, after some extreme adjustments in ACR, such as +4 exposure, +100 Brightness, 100 Fill Light, +100 Darks in the Tone Curve etc, the image looked almost presentable, apart from an over all green cast. A single click on 'AutoColor' in Photoshop fixed that.
I'm just flabbergasted that so much detail actually exists in a shot I was about to delete.
Ray,
Thanks for posting your findings. I also have the 800e but have not experienced such an underexposed shot and would not have thought that such results were possible. The take home point for me is that one should not carry ETTR too far--with such shadow performance, one can afford a bit of headroom for the highlights with the D800.
I see that you are using PV2010 with an older version of ACR. It would be interesting to see how PV2012 with its improved tone rendering would handle this image.
Regards,
Bill
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That's impressive! I have previously extracted what I thought was an astounding amount of detail from a very dark shot from my D800, but nothing like this.
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Ray,
Thanks for posting your findings. I also have the 800e but have not experienced such an underexposed shot and would not have thought that such results were possible. The take home point for me is that one should not carry ETTR too far--with such shadow performance, one can afford a bit of headroom for the highlights with the D800.
I see that you are using PV2010 with an older version of ACR. It would be interesting to see how PV2012 with its improved tone rendering would handle this image.
Regards,
Bill
Hi Bill,
I'm travelling at present and don't have access to the latest version of Photoshop, and because of the calibration limitations on laptops, I don't spend too much time attempting to get the most from an image.
However, as a result of my surprise with this extremely underexposed shot, I checked the DXO test results again to confirm that the D800E does have close to 1/2 a stop more DR than the D7000, at base ISO and equal size, and also noticed that the graph for the D800E DR is not completely straight from ISO 100 down. Between ISO 100 and ISO 200, the drop in DR is only about 1/2 a stop. This implies it would be better to use ISO 200 if one intends to underexpose significantly, rather than raise ISO significantly. The DR should be close to 1/2 a stop better at ISO 200. Would you agree?
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... noticed that the graph for the D800E DR is not completely straight from ISO 100 down. Between ISO 100 and ISO 200, the drop in DR is only about 1/2 a stop. This implies it would be better to use ISO 200 if one intends to underexpose significantly, rather than raise ISO significantly. The DR should be close to 1/2 a stop better at ISO 200. Would you agree?
That sounds about right. As I recall from looking at the DxO curves, raising ISO from 100 up to around 400 improves signal/noise, but after that there is no benefit to increasing ISO (apart from not scaring you with very dark preview images and histograms).
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That sounds about right. As I recall from looking at the DxO curves, raising ISO from 100 up to around 400 improves signal/noise, but after that there is no benefit to increasing ISO (apart from not scaring you with very dark preview images and histograms).
Looking again at those DXO curves, I don't see any advantage that would be noticeable, in moving from ISO 200 to 400. SNR at 18% falls by 2.8dB, which is close enough to 1 stop, or 3dB. And DR falls by 0.98 EV, which is close enough to 1 stop.
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I was very pleased with the camera's performance in general and would often marvel at how miraculously an almost totally dark image, underexposed at ISO 100 instead of properly exposed at ISO 6400, would spring to life with just a click on the 'auto' button in ACR.
Given the nature of the Exmor sensors ... and your interest in such things ... I'm surprised you are surprised.
Shooting in that manner and shooting at ISO 6400 should be almost indistinguishable on such an "iso-less" camera.
From the looks of the result, however, this would appear to be effectively past 6400 on the scale ...
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However, as a result of my surprise with this extremely underexposed shot, I checked the DXO test results again to confirm that the D800E does have close to 1/2 a stop more DR than the D7000, at base ISO and equal size, and also noticed that the graph for the D800E DR is not completely straight from ISO 100 down. Between ISO 100 and ISO 200, the drop in DR is only about 1/2 a stop. This implies it would be better to use ISO 200 if one intends to underexpose significantly, rather than raise ISO significantly. The DR should be close to 1/2 a stop better at ISO 200. Would you agree?
Ray,
I think you are correct. Unlike the D7000, the D800e is not "ISO less" as Marianne Oelund notes in this post (http://forums.dpreview.com/forums/post/40798097). With the D7000 one may leave the ISO at base and increase exposure in the raw converter when one is underexposing. With the D800e, one should use at least 200 and there may be some minimal improvement beyond that.
It is interesting that DXO rates the DR of the D800e at 14.33 at base ISO, which is interesting since a 14 bit linear file can encode only 14 stops of DR, at least in theory.
Regards,
Bill
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Bill,
It's only 13.23 in screen mode. On my computer the graphs don't update reliably, but clicking a couple of times between print mode and screen mode I get 13.23 in screen mode.
Best regards
Erik
Ray,
I think you are correct. Unlike the D7000, the D800e is not "ISO less" as Marianne Oelund notes in this post (http://forums.dpreview.com/forums/post/40798097). With the D7000 one may leave the ISO at base and increase exposure in the raw converter when one is underexposing. With the D800e, one should use at least 200 and there may be some minimal improvement beyond that.
It is interesting that DXO rates the DR of the D800e at 14.33 at base ISO, which is interesting since a 14 bit linear file can encode only 14 stops of DR, at least in theory.
Regards,
Bill
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Bill,
It's only 13.23 in screen mode. On my computer the graphs don't update reliably, but clicking a couple of times between print mode and screen mode I get 13.23 in screen mode.
Best regards
Erik
Erik,
Thanks for pointing that out, since I didn't think about screen vs print. I get 13.24 stops for screen from the site. It is nice to know that the laws of mathematics are not violated.
Bill
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Unlike the D7000, the D800e is not "ISO less" as Marianne Oelund notes in this post (http://forums.dpreview.com/forums/post/40798097). With the D7000 one may leave the ISO at base and increase exposure in the raw converter when one is underexposing. With the D800e, one should use at least 200 and there may be some minimal improvement beyond that.
It is interesting that DXO rates the DR of the D800e at 14.33 at base ISO, which is interesting since a 14 bit linear file can encode only 14 stops of DR, at least in theory.
Is there a reliable list of maximum "relevant" ISO settings for various cameras, beyond which results are no better than underexposing at a lower ISO speed setting and compensating later? Like seemingly 200 or 400 for the D800(E), and base ISO speed for the D7000.
In particular, I would like to know this for the EM5, because it could help me refine my use of the auto-ISO mode when there is not enough time to optimize settings before taking a photo.
P. S. wouldn't the rounding error in 14-bit be at most half a bit (and probably less in RMS terms), so that data rounded to 14 bits by a perfect 14-bit ADC could have a SNR of up to 2^15, which might be reported as 15 stops, or 15 bits?
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Very interesting. I'm wondering then what the ideal iso would be for something like shooting the night sky. Is the thought here that 200-400 or so would capture all the detail needed such that you could modify the image in post to achieve the results of say, 6400 iso? (if not better it)
So in theory... if you have proper post processing software... no reason to go above iso 400?
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Given the nature of the Exmor sensors ... and your interest in such things ... I'm surprised you are surprised.
Shooting in that manner and shooting at ISO 6400 should be almost indistinguishable on such an "iso-less" camera.
From the looks of the result, however, this would appear to be effectively past 6400 on the scale ...
Jeremy,
Have you been spending too much time on the Coffee Corner? ;D
I did use the past tense when I wrote, "I was very pleased with the camera's performance in general and would often marvel at how miraculously an almost totally dark image, underexposed at ISO 100 instead of properly exposed at ISO 6400, would spring to life with just a click on the 'auto' button in ACR."
When I bought the D7000, I was coming from a number of years experience with Canon DSLRs which had unrivalled high-ISO performance until the Nikon D3 hit the market, but unspectacular DR at base ISO. I have one or two shots from my 5D taken at night when the attached flash inadvertently did not fire. Despite the histogram of such shots looking a lot better than the D800E histogram pictured above, the noise and banding in the underexposed 5D shots was so bad it became a feature in itself. It created the impression of a photograph of a tapestry with a rather coarse weave, which I found quite interesting.
My renewed surprise at the low-light performance of the D800E was due partly to; (1) never having taken or processed such a drastically underexposed shot before; (2) partly due to my forgetting that the D800E should have around 1/2 stop greater DR than the D7000 at same image size, (half a stop of DR is at the threshhold which is clearly noticeable) and; (3) my previous version of Photoshop which I'd used to process D7000 images was CS3. I skipped CS4. I'm now using CS5 which I suspect might be doing a noticeably better conversion job with these underexposed NEF files.
Hope I've clarified this issue for you. ;D
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So in theory... if you have proper post processing software... no reason to go above iso 400?
Yes and no.
I have presets for every and each ISO value for my main camera on Lightroom.
If I import an ISO 3200 shot it will receive specific denoise values, very different from the ones that will be applied to an ISO 200/400 shot.
If you shoot at fixed low ISO you get the most of the quality and the most of the time in front of Lightroom :D
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Very interesting. I'm wondering then what the ideal iso would be for something like shooting the night sky. Is the thought here that 200-400 or so would capture all the detail needed such that you could modify the image in post to achieve the results of say, 6400 iso? (if not better it)
So in theory... if you have proper post processing software... no reason to go above iso 400?
As a result of starting this thread I've learned something myself about the performance of the D800E which I hadn't previously given much thought to. Looking again at the DR and SNR figures at various ISOs, on the DXOMark site, it seems to me that an exposure at base ISO that is 6 stops underexposed should have about one full stop worse DR than the same exposure at ISO 6400, with the D800E.
The figures I'm using to deduce this, are 14.33EV of DR at base ISO, and 9.23EV 6 stops down at ISO 6400. However, 14.33-9.23=5.1EV. What appears to be happening is one initially gains a 1/2 stop advantage by underexposing at ISO 200 instead of 100, then with each additional increase in ISO one gains an incremental DR advantage of around 0.1EV. These small amounts, in addition to that initial 1/2 stop advantage, add up to a total of a 0.9EV DR advantage using ISO 6400 instead of ISO 100.
However, SNR at 18% Grey diminishes more evenly as one reduces exposure. At base ISO it's 46dB. At ISO 6400 it's 28.1dB. 46-28.1=17.9dB. On the basis that 3dB is equivalent to a difference of one F stop in exposure, a drop in 6 stops of exposure should result in a drop of 18dB of SNR at 18%, which is approximately what one gets whether underexposing at base ISO or correctly exposing at ISO 6400.
These are the sorts of things one should easily be able to test for oneself using some practical real-world examples. I'll take a few underexposed shots tonight to see how they compare at ISO 100 and 6400.
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Just a couple of years ago I was considering upgrading from the Canon 50D to a 7D or 60D, mainly because of the video capability which none the DSLRs I owned at that time had.
However, when I saw the DR specs of the D7000 on the DXOMark website, I got very interested in that camera despite the fact that, at that time, I owned only one Nikkor lens, the 14-24/2.8 ultra-wide-angle zoom.
After some discussions on LL about the significance of shot noise at such low signal levels (some posters on LL seemed to think that any DR claims beyond about 12 stops for a small sensor would be an irrelevancy because shot noise would unavoidably mask any benefits), I took the plunge and bought a D7000 with Nikkor 24-120/F4 zoom.
After comparing the DR of my new D7000 with that of my Canon cameras, such as the 50D and the full-frame 5D, it became very apparent that the claimed 2-stop DR advantage of the D7000 was very real and only slightly obscured by the proportional increase in shot noise. I was very pleased with the camera's performance in general and would often marvel at how miraculously an almost totally dark image, underexposed at ISO 100 instead of properly exposed at ISO 6400, would spring to life with just a click on the 'auto' button in ACR.
The main attraction of the D800E for me was its incorporation into a larger sensor of all the qualities of the D7000. If fact, at equal image size, the D800E has about 1/2 a stop greater DR than the D7000, due to its larger sensor. However, I haven't taken the trouble to compare the DR of both cameras. I'm too busy enjoying photographing the real world.
It was while photographing the real world recently, in Thailand, I made the mistake of taking a shot at 1/60th, F8 and ISO 100 in manual mode, in near darkness at the end of the day, not realising the D800E's built-in flash was not still popped up. The review image was totally black. Not even a hint of a highlight. I didn't delete it due to laziness and the fact I was in a hurry to get back to the hotel before it got completely dark.
After downloading the day's images onto my Dell Notebook, and deleting a few mistakes and duds, I was about to delete the totally black preview in Bridge, of the F8 shot at 1/60th without flash, when curiosity got the better of me, and I decided to see just how noisy and awful this image really was.
When the image opened in ACR, the histogram showed just a single, thin, vertical line on the far left. There was absolutely no other information. Not even a little hump or two on the horizontal axis. Refer attached image.
However, after some extreme adjustments in ACR, such as +4 exposure, +100 Brightness, 100 Fill Light, +100 Darks in the Tone Curve etc, the image looked almost presentable, apart from an over all green cast. A single click on 'AutoColor' in Photoshop fixed that.
I'm just flabbergasted that so much detail actually exists in a shot I was about to delete. The purpose of the shot was to attempt to give a perspective on the actual size of this "Night Butterfly" (as it is locally known). I'd taken a few shots close up, with 24-120 zoom at 120mm, using the built-in flash, and as I was leaving the scene, still amazed at the enormous size of this butterfly, I decided to take a shot from a greater distance, hoping it would give a better impression of its great size.
Of course, "Night Butterfly" sounds more romantic than bloody Moth. But a check on the internet reveals it is in fact a moth, but the largest moth in the world, that goes by the name of Attacus Atlas. It's total wing surface area can be in excess of 62 sq inches (or 400 sq cm), and wing span in excess of 10". It's larger than my notebook on which I've processed the attached images. ;D
I've also shown a close-up of the moth taken when the flash was popped up. I thought it would immediately fly away, but it just twitched. I began to think it was maybe supremely confident because it had two snakes attached to its wings. It also had simulated patches of bamboo leaf on its wings as extra camouflage protection. Refer image 04, which I think is also rather abstract. If you think that detail is moire, don't hesitate to say so. ;D
It is a good device the 800e but not sure that it is any more amazing than other cameras. I am amazed at how clean the low iso files are from my d800e look on-screen, I am amazed at the resolution that my Nex7 produced with a good Leica tele and on a tripod on-screen at 100%, and I am amazed that I cannot tell the prints made on my 8 year old 1dsII with 70-200/II apart from the other two.
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Good grief. That's standard bamboo it is sitting on, right? Huuuuuge. Also very attractive.
And yes, I am duly impressed by the recovery of that sad histogram photo.
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However, SNR at 18% Grey diminishes more evenly as one reduces exposure. At base ISO it's 46dB. At ISO 6400 it's 28.1dB. 46-28.1=17.9dB. On the basis that 3dB is equivalent to a difference of one F stop in exposure, a drop in 6 stops of exposure should result in a drop of 18dB of SNR at 18%, which is approximately what one gets whether underexposing at base ISO or correctly exposing at ISO 6400.
These are the sorts of things one should easily be able to test for oneself using some practical real-world examples. I'll take a few underexposed shots tonight to see how they compare at ISO 100 and 6400.
Ray,
I think that the SNR relationship you document is due to photon counting statistics and has little to do with the sensor, provided that it has a linear response. AT 18% gray, the noise is almost all photon noise and the read noise contribution is minimal. Photon noise is present in the light before it hits the sensor. According to Poisson statistics, if one counts N photo-electrons, the noise is sqrt(N). The SNR is N/sqrt(N), which reduces to sqrt(N). With sensors, 6 dB equals one f/stop. Since dB is a log measure, one can determine the square root by dividing by 2. Increasing exposure by 1 f/stop (6 dB), will result in 3 dB increase in the SNR (and conversely). Perhaps one of the forum gearheads can comment further on this matter.
Regards,
Bill
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I've tried a few pix with my D800 at up to 25,000 and compared to the D700 at the same ISO, the D800 wins easily with no smear from the specular highlights that need lots of post. That said, I'm back from a month in Mallorca, Greece and Serbia shooting some stuff on the tripod and others using Hail Mary lighting and hand held.
My main body was the D800 with 24-120 f/4 and second the D700 with 17-35 f/2.8. Sometimes, I'd swap lenses when i knew I needed more res and a wider FOV.
I just looked at one of my Hail Mary photos shot in an 800-year old monastery with light streaming through the door and cranking up the D800 to just 6400. It was contrast city when I was shooting and I was blessed to be the fly on the wall. The image holds together well all the way from the sun-lit floor to the with aggressive NR in ACR (60 for luminance, 35 color), the image more than makes the grade!
For printing, I've got to reduce the size of the files which make the files even nicer.
In the overall scheme of things, once the ink hits the paper for me, I really can't tell the difference from one of my cameras when I'm printing smaller prints (less than 16x24), but looking at my edits from my time at this monastery, I almost wish I had a second D800 cranked up even a stop higher. I'm very sure that my images will work quite well at 20x30 and larger.
I tend to ignore the math and simply shoot the camera then deal with making an image. The math, though important to understanding the craft seldom comes across as an important element my final images. The final image is King in my book!
Attached is the final print (reduced) with a full-res crop of a section of the image from the same file.
As always, one's results may vary.
Bottom line for me is that the D800 makes the grade for high ISO shooting.
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Larry, impressive captures!
On a side note, your title contains a combination of Latin (Svetog) and Cyrillic (Cabe) letters. Proper Latin spelling would be "Save."
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A bit confused by all the talk of the 800 high iso performance. I'm gobsmacked by the recovery shown, I tried the same with my Canon X and got nowhere near that.
I also shot the D800 against the D4 and the X at high iso 6400, the D4 and X were much the same but the 800 was someway behind and struggled with the shadows. So as I say a bit confused at the 800 high iso experience I had. If I was shooting high iso the 800 is not the camera I would pick, so what happens between shooting it at 100iso and pushing in post between shooting at an original high iso. At the high iso I thought the DR was quite limiting, no denying the exceptional low iso DR performance. It must tail off pretty quickly somewhere up the iso scale?
Kevin.
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I just looked at one of my Hail Mary photos shot in an 800-year old monastery with light streaming through the door and cranking up the D800 to just 6400. It was contrast city when I was shooting and I was blessed to be the fly on the wall. The image holds together well all the way from the sun-lit floor to the with aggressive NR in ACR (60 for luminance, 35 color), the image more than makes the grade!
Very nice image!
Cheers,
Bernard
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A bit confused by all the talk of the 800 high iso performance. I'm gobsmacked by the recovery shown, I tried the same with my Canon X and got nowhere near that.
I also shot the D800 against the D4 and the X at high iso 6400, the D4 and X were much the same but the 800 was someway behind and struggled with the shadows. So as I say a bit confused at the 800 high iso experience I had. If I was shooting high iso the 800 is not the camera I would pick, so what happens between shooting it at 100iso and pushing in post between shooting at an original high iso. At the high iso I thought the DR was quite limiting, no denying the exceptional low iso DR performance. It must tail off pretty quickly somewhere up the iso scale?
Kevin.
I agree. The 800 is very much a low ISO camera and the DR tails off quickly as the ISO is cranked up. A D4 or a 1dx/5d3 is a better High ISO camera I feel but I value the 800 for its low ISO supremacy.
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I agree. The 800 is very much a low ISO camera and the DR tails off quickly as the ISO is cranked up. A D4 or a 1dx/5d3 is a better High ISO camera I feel but I value the 800 for its low ISO supremacy.
Do you care to furnish some data to back up your assertions? The DXO data tell a different story. The SNR at 18% saturation is virtually the same for both cameras, which is not surprising since both cameras have the same sensor size and collect the same amount of light and have similar shot noise (which is the predominant noise contribution at this saturation level). For engineering DR using the print values to account for the differing pixel counts of the two cameras, the D4 has a slight advantage. Since the D800 has more pixels and each pixel contributes read noise it has slightly less engineering DR, since read noise is in the denominator for this determination. For photographic DR where read noise is less a factor, the values would be more comparable.
You might want to read this white (http://www.dxomark.com/index.php/Publications/DxOMark-Insights/More-pixels-offset-noise!) paper by DXO.
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I agree. The 800 is very much a low ISO camera and the DR tails off quickly as the ISO is cranked up. A D4 or a 1dx/5d3 is a better High ISO camera I feel but I value the 800 for its low ISO supremacy.
I began by expressing my surprise at how much detail existed in such a seriously underexposed shot at ISO 100. However, Bill made the point that the D800 is not quite an ISO-less camera to the extent that the D7000 is.
The DR comparisons at DXOMark show a slight flattening of the curve for the D800 between ISO 100 and 200, and the DR figure at ISO 6400 is almost a stop less than the 6 stops down it should be if the graph were completely linear. This result implies there should be a slight DR advantage with the D800 when using a higher ISO setting rather than underexposing at base ISO, and some recent shots I took last night confirm this is indeed the case.
The noise or grain in the deepest shadows is noticeably coarser in the ISO 100 shots. I also notice a slight green cast in parts of the ISO 100 images, which would require more work to correct, but I haven't bothered. I suspect this green cast might be explained by the slight flattening of the Color Sensitivity graph as it approaches ISO 100. At high ISOs the difference in Color Sensitivity between one ISO and the next full stop of change is of the order of 1.5 bits, but between ISO 400 and 200 it's only 1.2 bits better, and between ISO 200 and 100, only 0.9 bits better.
The Nikon D4, according to the DXO comparisons graphs in attached image, does appear to have better DR at high ISO, particularly at ISO 1600 where it's 2/3rds of a stop better than the D800. However, the Canon 5D3 is hardly better than the D800 at any high ISO, to any degree that would be noticeable. The 1Dx matches the performance of the D4 at ISO 3200 and higher. However, at ISO 1600 it's no better than the D800, and at ISO 100, the DR of the 1Dx is a full 2 1/2 stops worse than the D800E.
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I agree. The 800 is very much a low ISO camera and the DR tails off quickly as the ISO is cranked up. A D4 or a 1dx/5d3 is a better High ISO camera I feel but I value the 800 for its low ISO supremacy.
The D800 is clearly superior at high ISO to the D3. The D3 is the camera that all sports photographers were calling incredibly (like in "I cannot believe my eyes") good at high ISO 4 years ago. The scenes we take pictures of have not changed in the mean time.
So I am not sure how the D800 can be called anything but an outstanding high ISO camera.
Cheers,
Bernard
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Hi,
I'm pretty sure Bill has a good point. Here is a plot tonal range plot of Nikon D800, Nikon D4 and Canon 1DX.
I guess that there are two points leading to the D800 called a low ISO camera:
1) If the image is viewed at actual pixels the D800 image is given a 40% disadvantage.
2) The Nikon at low ISO is very good but has more to loose with increasing ISO.
So I guess that D800 matches the "pro competition" up to 12000 ISO (or so) when correctly viewed.
Best regards
Erik
Do you care to furnish some data to back up your assertions? The DXO data tell a different story. The SNR at 18% saturation is virtually the same for both cameras, which is not surprising since both cameras have the same sensor size and collect the same amount of light and have similar shot noise (which is the predominant noise contribution at this saturation level). For engineering DR using the print values to account for the differing pixel counts of the two cameras, the D4 has a slight advantage. Since the D800 has more pixels and each pixel contributes read noise it has slightly less engineering DR, since read noise is in the denominator for this determination. For photographic DR where read noise is less a factor, the values would be more comparable.
You might want to read this white (http://www.dxomark.com/index.php/Publications/DxOMark-Insights/More-pixels-offset-noise!) paper by DXO.
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After reading such remarkable results, I decided to test my RX100.
Of course, results are not as good, but interresting when using LR4.2 for processing.
I've tried 0 to -7.3 fStop exposure in 1/3 sequence.
0 to -4 fStop give very good results up to A4, -5 Fstop is acceptable up to A6 (10x15), -6 is usable for web, and -7 as a memento ;)
The biggest diference with your D800E is that colors are falling off pretty quickly after 5 fStop.
Interresting correlation with ISO results, ISO 80(100 & 125) to 800 deliver good results, 1600 OK for 10x15, 3200 usable for web, and 6400 as a memento.
So, now I know that may underexpose without too many drawbacks.
Have a Nice day.
Thierry
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After reading such remarkable results, I decided to test my RX100.
Of course, results are not as good, but interresting when using LR4.2 for processing.
I've tried 0 to -7.3 fStop exposure in 1/3 sequence.
0 to -4 fStop give very good results up to A4, -5 Fstop is acceptable up to A6 (10x15), -6 is usable for web, and -7 as a memento ;)
The biggest diference with your D800E is that colors are falling off pretty quickly after 5 fStop.
Interresting correlation with ISO results, ISO 80(100 & 125) to 800 deliver good results, 1600 OK for 10x15, 3200 usable for web, and 6400 as a memento.
So, now I know that may underexpose without too many drawbacks.
Have a Nice day.
Thierry
Hi Thierry,
That sure is an impressive pocket camera. I guess the reason I don't have one is due to the fact I would find the maximum wide angle of 28mm and the maximum telephoto of 100mm a bit limiting. It would be great if someone could design a camera like the RX-100 with a choice of two or more quickly-interchangeable zoom leness, say, from 16-48mm and 50-300mm, or if that's too difficult, provide different flavours of the same camera with different fixed-zoom lenses. The camera is so light one could easily carry two of them at the same time.
Checking the DXO graphs for this camera I'm amazed that the DR of the RX-100 is well over a stop better than that of my Canon 5D, at base ISO. ISO 400 seems to be the cross-over point where DR is equal for both cameras. At higher ISOs, the RX-100 gets left behind, which is not surprising considering that the sensor area is less than 1/7th that of the full-frame 5D.
SNR at 18% is another story though. As someone coming from the world of MFDB, I guess you wouldn't be too happy about that. ;)
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Hi,
Having the RX100 I must say I'm quite impressed. Image quality at low ISO and at the wide end is pretty close to my full frame 24MP DSLRs. The long end is something else, it's still sharp in the middle bat sharpness drops rapidly to the corners, at least on mine.
It is also quite usable at high ISO.
Regarding SNR I think that DxO-s "tonal range" is probably the nicest and most telling. See the enclosed plot of RX100, D3200 (APS-C) and canon 5DII (full frame). Tonal range is about collecting photons and here bigger is mostly better.
I also added the tonality plot of the Canon 5DIII, Nikon D4 and the Phase One IQ180. Interestingly, the curves almost overlap! The Phase One is capable of the highest "tonal range" but only at low ISO. What we see here is that the MFDB has advantage of sensor size but has much worse "quantum efficiency" compared to the Nikon D4 and the Canon 5DIII.
Quantum efficiency aside, I have a feeling that Canon, Nikon and also Sony have improved the full well capacity of the pixels, too.
Best regards
Erik
Hi Thierry,
That sure is an impressive pocket camera. I guess the reason I don't have one is due to the fact I would find the maximum wide angle of 28mm and the maximum telephoto of 100mm a bit limiting. It would be great if someone could design a camera like the RX-100 with a choice of two or more quickly-interchangeable zoom leness, say, from 16-48mm and 50-300mm, or if that's too difficult, provide different flavours of the same camera with different fixed-zoom lenses. The camera is so light one could easily carry two of them at the same time.
Checking the DXO graphs for this camera I'm amazed that the DR of the RX-100 is well over a stop better than that of my Canon 5D, at base ISO. ISO 400 seems to be the cross-over point where DR is equal for both cameras. At higher ISOs, the RX-100 gets left behind, which is not surprising considering that the sensor area is less than 1/7th that of the full-frame 5D.
SNR at 18% is another story though. As someone coming from the world of MFDB, I guess you wouldn't be too happy about that. ;)
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D800 (and rx100) users: do you feel that 18% SNR figures are relevant to your photography?
-h
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D800 (and rx100) users: do you feel that 18% SNR figures are relevant to your photography?
In fact... yes.
As long as we use cameras, the technicalities thereof are relevant.
Most drivers don't feel that a torque curve/efficiency curves are important to their driving/wallet, but in fact... they are.
Cheers,
Bernard
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D800 (and rx100) users: do you feel that 18% SNR figures are relevant to your photography?
-h
I really do. :)
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Hi,
Having the RX100 I must say I'm quite impressed. Image quality at low ISO and at the wide end is pretty close to my full frame 24MP DSLRs. The long end is something else, it's still sharp in the middle bat sharpness drops rapidly to the corners, at least on mine.
It is also quite usable at high ISO.
Regarding SNR I think that DxO-s "tonal range" is probably the nicest and most telling. See the enclosed plot of RX100, D3200 (APS-C) and canon 5DII (full frame). Tonal range is about collecting photons and here bigger is mostly better.
I also added the tonality plot of the Canon 5DIII, Nikon D4 and the Phase One IQ180. Interestingly, the curves almost overlap! The Phase One is capable of the highest "tonal range" but only at low ISO. What we see here is that the MFDB has advantage of sensor size but has much worse "quantum efficiency" compared to the Nikon D4 and the Canon 5DIII.
Quantum efficiency aside, I have a feeling that Canon, Nikon and also Sony have improved the full well capacity of the pixels, too.
Best regards
Erik
Hi Erik,
I think at this stage we need to specify how differences in the measurements as displayed on the graphs are significant in practice. The units used vary, depending on the specification. With regard to DR we have units of EV (exposure value) which are equivalent to a one stop difference in exposure. I think DXOMark have stated somewhere that anything less than a 0.5EV difference in DR is of little consequence, and probably unnoticeable.
Likewise, with regard to Color Sensitivity, which is measured in bits, anything less than 1 bit is of little concern.
I wonder if the same applies to Tonal Range, which is also measured in bits. A difference in excess of one bit may be worth something. A difference of less than one bit can be ignored, for most practical purposes.
A difference of 3dB in SNR appears to be the threshold which is noticeable. Differences less than 3dB are of little consequence,
These are the standards I use. If camera A has a 1/2 stop better DR than camera B, whether at high ISO or low ISO, I'm not particularly fussed. A one-stop increase in DR seems to be worth something. A two-stop increase in DR is spectacular, just as a 6dB increase in SNR is, and maybe a 2 bit increase in tonal Range.
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Do you care to furnish some data to back up your assertions? The DXO data tell a different story. The SNR at 18% saturation is virtually the same for both cameras, which is not surprising since both cameras have the same sensor size and collect the same amount of light and have similar shot noise (which is the predominant noise contribution at this saturation level). For engineering DR using the print values to account for the differing pixel counts of the two cameras, the D4 has a slight advantage. Since the D800 has more pixels and each pixel contributes read noise it has slightly less engineering DR, since read noise is in the denominator for this determination. For photographic DR where read noise is less a factor, the values would be more comparable.
You might want to read this white (http://www.dxomark.com/index.php/Publications/DxOMark-Insights/More-pixels-offset-noise!) paper by DXO.
NO, I have neither data nor graphs and I have no interest whatsoever in reading any whitepapers on the subject. It is merely my personal observation that the DR advantage of my D800e disappears quite quickly as ISO is increased. Once that advantage disappears it is my personal view that there are better handling and better featured cameras out there (e.g. D4, 5dIII, D1X, OMD, etc. etc.).
A quick look at the plethora of graphs that indignantly sprung up, yours included, at my first utterance of anything approaching criticism of the D800 seem to support this view (at least the first part of it), but what do I know.
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NO, I have neither data nor graphs and I have no interest whatsoever in reading any whitepapers on the subject. It is merely my personal observation that the DR advantage of my D800e disappears quite quickly as ISO is increased. Once that advantage disappears it is my personal view that there are better handling and better featured cameras out there (e.g. D4, 5dIII, D1X, OMD, etc. etc.).
A quick look at the plethora of graphs that indignantly sprung up, yours included, at my first utterance of anything approaching criticism of the D800 seem to support this view (at least the first part of it), but what do I know.
It's now clear to me that the D800E is not an ISO-less camera, and that shots at ISO 6400, for example, compared with the same exposure at ISO 100, have more detail in the deep shadows, and more accurate color rendition.
The 5D3 may have better specs in some respects, than the D800E, but DR and SNR are not amongst them.
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NO, I have neither data nor graphs and I have no interest whatsoever in reading any whitepapers on the subject. It is merely my personal observation that the DR advantage of my D800e disappears quite quickly as ISO is increased. Once that advantage disappears it is my personal view that there are better handling and better featured cameras out there (e.g. D4, 5dIII, D1X, OMD, etc. etc.).
A quick look at the plethora of graphs that indignantly sprung up, yours included, at my first utterance of anything approaching criticism of the D800 seem to support this view (at least the first part of it), but what do I know.
Alistair,
If you actually have these cameras, why don't you publish some photos on the forum to back up your assertions regarding ISO or else cease and desist? Ray's results show quite the opposite to what you say.
Regards,
Bill
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In fact... yes.
As long as we use cameras, the technicalities thereof are relevant.
Most drivers don't feel that a torque curve/efficiency curves are important to their driving/wallet, but in fact... they are.
Cheers,
Bernard
It may well be possible to measure everything that is relevant, but surely not everything that can be measured is relevant. To continue your car analogy: one car may have 10 dB better FM radio sensitivity than another, but this has no influence on what car will win a race...
My question was how the 18% SNR measurements extends what can be learned from DR measurements in a way that is relevant for my/your/... photography.
...The SNR at 18% saturation is virtually the same for both cameras, which is not surprising since both cameras have the same sensor size and collect the same amount of light and have similar shot noise (which is the predominant noise contribution at this saturation level).
So could we just ditch the 18% SNR measurement and state that "bigger is better" (in this respect, at least)? Does it matter? I.e. would my A3+ prints appear visually better if my 7D had better SNR@18%, "everything else being equal"?
My uneducated gut-feeling is that noise (even worse: patterned noise) in the shadows are a much more relevant problem than shot-noise at mid-gray. But perhaps I am misinterpreting the measurements and their implications. If so, I would be pleased to be educated.
-h
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It's now clear to me that the D800E is not an ISO-less camera, and that shots at ISO 6400, for example, compared with the same exposure at ISO 100, have more detail in the deep shadows, and more accurate color rendition.
The 5D3 may have better specs in some respects, than the D800E, but DR and SNR are not amongst them.
Merely by looking at the DR graphs, one cannot determine if the departure from linearity at low ISO is from impaired performance at base ISO or from improved performance at higher ISO. Marianne states that the latter is the case and the D800 is better than ISOless. This DPR thread (http://forums.dpreview.com/forums/post/42052105) amplifies the subject.
Regards,
Bill
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It may well be possible to measure everything that is relevant, but surely not everything that can be measured is relevant. To continue your car analogy: one car may have 10 dB better FM radio sensitivity than another, but this has no influence on what car will win a race...
My question was how the 18% SNR measurements extends what can be learned from DR measurements in a way that is relevant for my/your/... photography.So could we just ditch the 18% SNR measurement and state that "bigger is better" (in this respect, at least)? Does it matter? I.e. would my A3+ prints appear visually better if my 7D had better SNR@18%, "everything else being equal"?
My uneducated gut-feeling is that noise (even worse: patterned noise) in the shadows are a much more relevant problem than shot-noise at mid-gray. But perhaps I am misinterpreting the measurements and their implications. If so, I would be pleased to be educated.
-h
I'm confused here, h. What's your point? As I understand, DR refers to SNR at extremely low signal levels, ie, the deep shadows. SNR at 18% refers to noise levels in the mid-tones which are relevantt for smooth skin tones. MFDB excels in this area.
As I understand, the DXOMark results for DR performance could be described as SNR at 1% to 0.1%, insted of 18%. Is there more to it than that?
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Hi,
18% SNR is what you probably would have on facial tone or deep blue sky. These are typically surfaces you would like to have smooth tonality.
With a wide dynamic range it is well possible that we never utilize the low end. Shadow detail is normally kept pretty dark and would be even more compressed in printing.
You can extend dynamic range downwards, but it does not help on mid tones.
Keep also in mind that DxO measurements are about the amount of noise and not the quality of the noise.
Best regards
Erik
My uneducated gut-feeling is that noise (even worse: patterned noise) in the shadows are a much more relevant problem than shot-noise at mid-gray. But perhaps I am misinterpreting the measurements and their implications. If so, I would be pleased to be educated.
-h
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I'm confused here, h. What's your point? As I understand, DR refers to SNR at extremely low signal levels, ie, the deep shadows. SNR at 18% refers to noise levels in the mid-tones which are relevantt for smooth skin tones. MFDB excels in this area.
As I understand, the DXOMark results for DR performance could be described as SNR at 1% to 0.1%, insted of 18%. Is there more to it than that?
I don't know. I wish that someone was able to convey this topic once and for all using some simple graph. Ala the placeholder included below (only designed by someone who knew the physics and engineering approximations):
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Merely by looking at the DR graphs, one cannot determine if the departure from linearity at low ISO is from impaired performance at base ISO or from improved performance at higher ISO. Marianne states that the latter is the case and the D800 is better than ISOless. This DPR thread (http://forums.dpreview.com/forums/post/42052105) amplifies the subject.
Regards,
Bill
Does it matter? For the practical photographer, what matters is maximum DR and SNR at all ISOs. Currently, cameras which excel at high ISO, such as the D4 and the D3s, do not excel at low ISO to the same degree. There's a trade-off.
Cameras which excell at low ISO may not compete with cameras designed to to excell at high ISO. The D4 beats the D800 at high ISO, but the D800 beats the D4 at low ISO.
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I don't know. I wish that someone was able to convey this topic once and for all using some simple graph. Ala the placeholder included below (only designed by someone who knew the physics and engineering approximations):
The most complete description of noise in the DXO analysis is the full SNR plot. Emil Martinec (http://www.luminous-landscape.com/forum/index.php?topic=42158.0) explaines engineering DR and shows how to determine the photographic DR for any given noise floor. The full SNR plot may also be used for determination of the tonal range of a camera, which is the number of discrete gray levels that the sensor can discriminate, expressed as the number of bits necessary to encode these levels. In Michael's original ETTR post, he spoke of the number of levels in the brightest f/stop and assumed that this was related to the bit depth of the sensor. However, it does not make sense to quantify the sensor response in finer steps than the noise level.
Consider the full SNR plot for the D800e (shown below). In scientific papers it is common to plot the standard error as bars above and below the observed value to show the error of the measurement (see here (http://learnmem.cshlp.org/content/8/6/326/F3.expansion) for an example). We can do the same for the full SNR plot. The vertical arrowed bar is the standard deviation of the noise for a given pixel value. The true value of pixel should lie between the upper and lower bounds for this pixel level as shown by the green arrow. If one repeats the process from shadows to highlights and places the black arrows side by side, that is the number of discrete gray levels that the sensor can detect. This number may be expressed as the number of bits necessary to encode it.
Regards,
Bill
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Alistair,
If you actually have these cameras, why don't you publish some photos on the forum to back up your assertions regarding ISO or else cease and desist? Ray's results show quite the opposite to what you say.
Regards,
Bill
Well if you want proof of the low ISO performance of the D800e here are some from today; all OOC jpegs. As I am trying to point out, I neither need nor use high ISO and if I did I would not buy a D800/e. At this point I am going to take your desist option and bow out of the thread, this stuff is of no interest to me. Go well.
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After all the number talking and curve plotting, I'm for going out and simply shooting and enjoying the pleasant surprise of getting an image today that yesterday, the technology limitations didn't allow!
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Do you care to furnish some data to back up your assertions? The DXO data tell a different story. The SNR at 18% saturation is virtually the same for both cameras, which is not surprising since both cameras have the same sensor size and collect the same amount of light and have similar shot noise (which is the predominant noise contribution at this saturation level). For engineering DR using the print values to account for the differing pixel counts of the two cameras, the D4 has a slight advantage. Since the D800 has more pixels and each pixel contributes read noise it has slightly less engineering DR, since read noise is in the denominator for this determination. For photographic DR where read noise is less a factor, the values would be more comparable.
You might want to read this white (http://www.dxomark.com/index.php/Publications/DxOMark-Insights/More-pixels-offset-noise!) paper by DXO.
I've said many a time I could not give a stuff about results that come from meter derived conclusions. I don't need data to back it up, just eyes. I would suggest you shoot them side by side and judge for yourself and not depend on third party graphs.
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I've said many a time I could not give a stuff about results that come from meter derived conclusions. I don't need data to back it up, just eyes. I would suggest you shoot them side by side and judge for yourself and not depend on third party graphs.
"Experience keeps a dear school, but fools will learn in no other"
-Franklin, Benjamin
There is no contradiction between doing good measurements and doing good side-by-sides.
-h
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I've said many a time I could not give a stuff about results that come from meter derived conclusions.
You have.
You read these threads in which say you have no interest, and then you declare your 'independence'.
Right on cue. 8)
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"Experience keeps a dear school, but fools will learn in no other"
-Franklin, Benjamin
There is no contradiction between doing good measurements and doing good side-by-sides.
-h
Not a contradiction but an over-reliance on measurements isn't good either.
I haven't used the term in many months, having been chastised for it in the past, but this type of discussion is precisely where the term 'measurebator' comes from. Test analysis from outlets like DxO Mark and others are fine and using that information as a part of the research into a new camera is fine but in the end few, if any, of us spend our time making images in a highly controlled lab setting. Even a studio with 'controlled' lighting isn't as static as a lab.
In addition, too many people tout the hype of the test numbers without inquiry. DxO Mark's headline test numbers for the D800/e are terrific. But those numbers are massaged. How many people actually realise that? I'd venture it's a minority.
Most of us are actual photographers. I'd like to think that it's the relative minority that pore over images at sub-pixel level magnifications on a computer screen for hours on end looking for the most minute imperfection. Or spend countless thousands of dollars on cameras that are capable of making spectacular images with immense amounts of data captured in a raw file to then simply post 720x540 pixel jpegs on the web. Photography is a visual endeavour. So while we may look at test results from 'reputable' outlets, in the end it is what we see with our eyes that tells the tale. Clients don't ask what the SNR of a picture is. Clients don't ask what the dynamic range of a camera is. Clients don't ask if a sensor is ISO-less. They couldn't care-less.
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... Clients don't ask what the SNR of a picture is. Clients don't ask what the dynamic range of a camera is. Clients don't ask if a sensor is ISO-less. They couldn't care-less.
Clients also do not know or care what f/stop or ISO is, but shouldn't you?
They don't because they assume you do. And you do because you learned it at some point. And learning it required measuring... yours, or someone's else.
And that's what we are doing here, in this thread.
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It will likely come as no surprise, Slobodan that I disagree. There's a difference between the technical skill or knowledge required to get the desired result in the form of a photograph and measurebating or pixel-peeping.
I don't think it takes a full understanding of, for example, Emil's treatise on noise to really understand what noise in a digital image is and that less is generally better. I don't think it takes an engineering degree to realise that, for the most part, today's cameras are better than ones that came before in terms of noise performance/characteristics and dynamic range, among other things. It doesn't take measuring in a lab to determine that. The original post in this discussion thread bears that out quite well.
I don't give a flying fadoo whether a particular camera measures 10db or 100db. I don't care what the actual measurement is because it's a meaningless number. But I want to see what the difference is between the two cameras. The number tells me that the second camera is inherently better - has a better SNR - but I also don't need to measure it to see it. So no, I don't believe that learning necessarily involves measuring, at least not to the exclusion of anything else. I don't believe the two are interdependent.
Contrary to what your comment may seem to indicate, I'm not opposed to lab tests; and said as much in my previous remarks. I read them and take the information into account when I'm evaluating a new camera or lens. But my point is there's more to it than just the lab numbers and that an over-reliance on the lab numbers alone isn't a good approach.
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It will likely come as no surprise, Slobodan that I disagree. There's a difference between the technical skill or knowledge required to get the desired result in the form of a photograph and measurebating or pixel-peeping.
I know from experience that my family thinks that using a DSLR or pointing your flash towards the ceiling is the equivalent of "pixel-peeping": they use their compact cameras in full auto, have the internal flash making for the "deer in headlights", but they focus on the content. So should we all do as them?
It is easy to claim that obsessing with DOF and scheimpflug and golden angle and such can stand in the way of capturing the great scenes that come and go. Perhaps it is so. I think it is fair to choose ones own approach to a hobby or profession. You may call it "measurebating" as much as you want, it simply does not make your arguments any more intelligent or relevant for your readers.
I don't think it takes a full understanding of, for example, Emil's treatise on noise to really understand what noise in a digital image is and that less is generally better. I don't think it takes an engineering degree to realise that, for the most part, today's cameras are better than ones that came before in terms of noise performance/characteristics and dynamic range, among other things. It doesn't take measuring in a lab to determine that. The original post in this discussion thread bears that out quite well.
I believe that there are numerous examples where "hands on" people have given advice such as "use ISO 160 instead of ISO 100 or ISO 200, as it is less noisy" or "this camera sensor have more headroom, but that camera sensor have more footroom", where it turns out that their practical "show me the images" testing was flawed, and a more physically motivated testing methology have shown that their advice was poor.
This thread indicates that among "dedicated photographers" on this blog, there is disagreement over what current camera models gives the best result at low light levels vs at high light levels. If people buy a D4 but could have had better results with a D800, is that not reason enough to welcome good, relevant measurements (and fair side-by-sides)? I am not defending poor measurements or misinterpreted measurements, nor am I defending unfair/irrelevant subjecive side-by-sides.
-h
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... I don't think it takes an engineering degree to realise that, for the most part, today's cameras are better than ones that came before in terms of noise performance/characteristics and dynamic range, among other things. It doesn't take measuring in a lab to determine that....
On the contrary, it is precisely thanks to the measurbators, pixelpeepers and lab measuring that "today's cameras are better than ones that came before."
So, say "thank god for measurbators," and if it is beyond your comprehension or interest, skip the thread and move on.
Complaining about measurbators in their own thread is as meaningful as attending a church service to argue about god existence.
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Contrary to what your comment may seem to indicate, I'm not opposed to lab tests; and said as much in my previous remarks. I read them and take the information into account when I'm evaluating a new camera or lens. But my point is there's more to it than just the lab numbers and that an over-reliance on the lab numbers alone isn't a good approach.
I see ... you are just looking out for those of us who aren't quite as sophisticated as you are when it comes to avoiding such "over-reliance".
What a load of horse-shit! That's a pretty condescending and self-aggrandizing position to take.
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Not really sure why you've taken my comment so personally, Jeremy. There was nothing arrogant, self-aggrandising or condescending intended in the statement. What I was merely saying was that too great a leaning on one or the other approach to evaluating a camera, or lens, or flash, or whatever isn't the best approach. To read that as my 'looking out for' anyone is beyond absurd. There's not a shred of logic in such an interpretation. Agree or disagree all you want but if you're going to take such personal affront to my stating my opinion, well then fuck you.
Slobodan, I'm sorry but that's nonsense. You're claiming that sites like DPReview or DxO Mark are the only reason there has been innovation in the camera market? That's like saying Ralph Nader is the only reason there's been innovation in cars. It's preposterous. You're saying that companies won't innovate on their own? Come on. It's not beyond my comprehension. Nor is it entirely without interest. For crying out loud read what's actually written.
h, no that's not what I'm saying. And again read what I said about the technical knowledge to take a good picture being different from the knowledge of the inner workings of a camera. I don't need to know how precisely a rotary engine works to be able to drive a Mazda. WRT the 'use ISO 160' or whatever other similar message, again, I'm not opposed to data. If someone can post accurate data that refutes a subjective statement then that's fine. I think we both know that there's ample 'bad data' out there too. This article (http://www.digitalphotopro.com/gear/cameras/the-truth-about-digital-iso.html) and the referenced video on Vimeo stirred up quite a bit of controversy a while back. Good data or bad data? But it doesn't need to be a doctoral dissertation on the subject to do that. As far as 'better' results with a D4 or D800, better is a wildly subjective term. What is 'better' in one instance for one person may not be for another. Yes, I do think that at times people can get caught up in the details and lose good pictures as a result. It's also true; however, that technically perfect pictures aren't always the best either.
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Hi,
I would just say that it is really nice to have a first class camera at a reasonable price. The D800 is something like 3000 $US below the D4, for many of saving 3000$US is quite significant. So if the D800 offers D4 like high ISO quality is not just about mesurbation but about saving money. The other side of the coin that the D800 also gives you 36 MPixels.
Yes, you can do your own test. Just get a rental on all pieces, read the fine manuals, set up a few test subjects and do some well executed test shots, avoid mistakes and learn to process your files optimally and than do an educated choice.
Best regards
Erik
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... Jeremy... To read that as my 'looking out for' anyone is beyond absurd....
... Slobodan...For crying out loud read what's actually written.
... h, no that's not what I'm saying...
Seems like a lot of people do not know how to read what you are saying.
Could it be that the problem is in what you are saying and how?
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Truthfully, no I don't think so. I think it's more a case of people with an agenda twisting or inferring meanings to suit that agenda.
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Truthfully, no I don't think so. I think it's more a case of people with an agenda twisting or inferring meanings to suit that agenda.
Is it still paranoia if they REALLY ARE out to get you?
Thanks for the laugh of the week, Bob. Truly.
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I think it's more a case of people with an agenda twisting or inferring meanings to suit that agenda.
Aaahhhh... so you do not have any agenda? I am glad this is cleared now.
I must have been confused by the many posts you have written about the lack of actual benefits of the technologies embedded in cameras not bearing a Canon logo, in particular the D800. ;)
Cheers,
Bernard
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Truthfully, no I don't think so. I think it's more a case of people with an agenda twisting or inferring meanings to suit that agenda.
Since the quote seems to refer to me, Slobodan and Jeremy: What is my agenda? In what way am I twisting your meanings? Please provide support for your accusations.
In the mean time, perhaps you can try to explain what you really think, because your posts leave me confused. You seem to be saying that:
Measurements can sometimes be poorly carried out or misinterpreted
It is hard to disagree on that. Given that we all agree that a given measurement _can_ be of little use for a given problem, what is the point in repeating that ad infinitum?
...Good data or bad data? But it doesn't need to be a doctoral dissertation on the subject to do that.
Are you saying that doing measurements and interpreting them is simple? I tend to disagree: there is a reason why we educate PhDs: doing measurements of some kind that are repeatable, applicable outside of the lab and sufficiently novel that the results actually add to the accumulated human knowledge is quite hard.
I believe that I have given you examples where misguided experts/reviewers have given bad advice based on their home-brew "down-to-earth" testing methology. In other words: while a PhD may not be needed to do measurements and analyze their results, there are plenty of examples of good practitioners (without a PhD) giving poor advice.
As far as 'better' results with a D4 or D800, better is a wildly subjective term. What is 'better' in one instance for one person may not be for another.
I don't think it takes a full understanding of, for example, Emil's treatise on noise to really understand what noise in a digital image is and that less is generally better.
I don't think it takes an engineering degree to realise that, for the most part, today's cameras are better than ones that came before in terms of noise performance/characteristics and dynamic range, among other things.
So which is it... Are some cameras "better" or is it all subjective?
.
Yes, I do think that at times people can get caught up in the details and lose good pictures as a result. It's also true; however, that technically perfect pictures aren't always the best either.
You seem to be argueing against a strawman here. Everyone (?) agrees that technical issues are only one component of the final image.
Contrary to what your comment may seem to indicate, I'm not opposed to lab tests; and said as much in my previous remarks.
That is good to hear.
I read them and take the information into account when I'm evaluating a new camera or lens. But my point is there's more to it than just the lab numbers and that an over-reliance on the lab numbers alone isn't a good approach.
So who among the thread-contributers is it that does this, in your view? Or are you discussing hypothetical problems?
-h
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I think it's more a case of people with an agenda twisting or inferring meanings to suit that agenda.
Yes, I, too would like to know what my secret agenda is.
It would be much easier to make the correct inferences to suit that agenda if I knew what it was ... please, do tell!
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I must have been confused by the many posts you have written about the lack of actual benefits of the technologies embedded in cameras not bearing a Canon logo, in particular the D800. ;)
Cheers,
Bernard
What? First, I don't shoot Canon. Used to. Don't any longer. So pumping up Canon isn't something I'd really be interested in doing. Second, I've never said that the D800 was a bad camera. Never. What I have said is that it isn't the camera I wanted from Nikon as a successor to the D700. Despite that, since Nikon isn't, apparently, going to build the camera I (and a lot of other people) want, I did break down and buy one. Much to my own chagrin. ::)
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Bobfisher,
I really can't understand your concerns here. Have you got some sort antagonism against graphs? Do you suffer from graphobia (or should that be graphphobia)? ;D
In my view the incessant arguing and bickering over differences in the various aspects of a camera's comparative technical performance, as often seen at sites such as dpreview, is due to a lack of appreciation of the significance of the sorts of measurements conducted by DXO.
However, I do understand that for anyone who is not familiar with the units used in the graphs, such data may not be at all illuminating. There's a basic requirement, which is surely not unreasonable, for a person to familiarize himself with the significance of the units used, before they become meaningful. And DXOMark, in their various articles and descriptions of the performance aspects they have measured, do provide explanations of what the units mean and how significant the differences in values may be.
For example, DR is measured in Exposure Values, abbreviated as EV, and a difference in one EV is equivalent to a difference in one F stop of exposure, all else remaining the same. DXOMark also mention that a difference of 0.5EV (or 1/2 a stop) will probably be noticeable, implying that differences of less than 1/2 a stop may not be noticeable.
This is the sort of information which I find useful when making a decision whether or not to buy a new camera. Without such reliable measurements, I might be tempted to make a decision based upon hyperbole and misinformation which can abound in the absence of reliable measurements, each news source just repeating the misinformation or biased view already perpetrated.
For example, to extend Erik's analogy, we already have comments in this thread that cameras such as the Nikon D4 and Canon 1DX have better high-ISO performance than the D800. Do you really not want to know how much better and over what range of high ISOs the D4 is better? The DXOMark graphs will give you a reliable indication of what to expect.
Perhaps you rarely shoot above ISO 400 with your D800 (if you have one) because of noticeable image degradation, but you've heard that the D4 has amazing high-ISO performance, so you buy the camera hoping that at last you can get clean images at high ISO.
How are you going to feel if you later discover the truth, that the D4 only has better DR than the D800 above ISO 800, in other words, at ISOs which you never use because they are too noisy? A 1/2 stop improvement in DR at ISO 1600 is still worse than DR at ISO 800 using either camera, and significantly worse than DR at ISO 400 with the D800.
How are you going to feel when you discover that any improvement in high-ISO noise from the D4 is only apparent in the deep shadows by a barely noticeable degree, and that SNR over most of the tonal range at high ISOs is no better than that of the the D800, nor is Color Sensitivity any better?
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Ray, your response is so completely ridiculous and childish that it deserves no more response than that.
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I admit my responses so far are so completely ridiculous and childish that they deserve no more response than that.
Oooooops!
Did I just misquote/misread what you wrote, again? My bad ;)
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Ray, your response is so completely ridiculous and childish that it deserves no more response than that.
"Calling all secret agendas! We have a live one in Sector 9!"
You are dropping 'ef bombs and conspiracy theories ... And Ray is being ridiculous and childish?
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"Calling all secret agendas! We have a live one in Sector 9!"
You are dropping 'ef bombs and conspiracy theories ... And Ray is being ridiculous and childish?
Yeah, you deride me for cursing after doing it yourself. What's that word I'm looking for.... hy.... hyp-something.... hypocritical, that's it.
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... 18% SNR is what you probably would have on facial tone or deep blue sky. These are typically surfaces you would like to have smooth tonality.
With a wide dynamic range it is well possible that we never utilize the low end. Shadow detail is normally kept pretty dark and would be even more compressed in printing.
Thanks for that comment Erik. Although there are situations where extreme DR is important (like scenes of unusually high Subject Brightness Range or forgetting to set the ISO speed appropriately when photographing moths at dusk), I would say that the vast majority of photography involves not much more that the traditional "normal" SBR of about three stops either side of mid-tones. Indeed the ASA/ISO film speed scale incorporated a similar idea, giving a speed that is the maximum Exposure Index that keeps the "noise floor" of the film about four stops below normal mid-tone placement.
With a typical mid-tone placement at about 12-18% of maximum diffuse luminosity, that puts the lower end of the commonly interesting luminosity levels at about 1-2%. So I would say that for the purpose of _most_ low light/high ISO speed photography, what matters most to the visible noise levels in the final displayed image is the SNR at various levels in this range, say down to 1%, or over the range of about seven stops down from highlight placement, or down to four stops below mid-tone placement. I would be far more interested in measurements and photographic examples of "performance over a given luminosity range" like this than I am in measurements of an extreme like "DR down to 1:1 SNR". Such quantification of extremes is often of dubious direct practical relevance, in the way that extinction resolution is less informative than MTF50.
The 18% SNR data are a useful start, and for good modern sensors like the D800(E) these seem to be dominated by photon shot noise up to very high ISO speeds, but I would expect sensor noise to become relevant about three stops lower if one also looks at noise down to some moderate-to-deep shadow level.
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Yeah, you deride me for cursing after doing it yourself. What's that word I'm looking for.... hy.... hyp-something.... hypocritical, that's it.
I'm not deriding you for cursing.
I'm making fun of you for other stuff ... Like cursing and claiming secret agendas while calling Ray childish ... or proclaiming that the rest of us aren't capable of using scientific data properly ...
That's not mocking you for cursing ... that's mocking you for ... let's just call it unintentional irony.
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or proclaiming that the rest of us aren't capable of using scientific data properly ...
That comment is a perfect example of what I mentioned earlier. Nowhere, nowhere did I say that people weren't able to properly use data. There is absolutely no possible way that inference can logically or factually be gleaned from any remarks I've made.
That is a fabrication of your own, personal insecurities and I take no responsibility for those. That's something you'll have to deal with on yourself.
I'm done with this thread.
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With a typical mid-tone placement at about 12-18% of maximum diffuse luminosity, that puts the lower end of the commonly interesting luminosity levels at about 1-2%. So I would say that for the purpose of _most_ low light/high ISO speed photography, what matters most to the visible noise levels in the final displayed image is the SNR at various levels in this range, from down 1%, or over the range of 6-7 stops down from highlight placement, or down to 3-4 stops below mid-tone placement. I would be far more interested in measurements and photographic examples of "performance over a given luminosity range" like this than I am in measurements of an extreme like "DR down to 1:1 SNR". Such quantification of extremes is often of dubious direct practical relevance, in the way that extinction resolution is less informative than MTF50.
The 18% SNR data are a useful start, and for good modern sensors like the D800(E) these seem to be dominated by photon shot noise up to very high ISO speeds, but I would expect sensor noise to become relevant about three stops lower if one also looks at noise down to some moderate-to-deep shadow level.
That makes sense to me. The engineering DR reported by DXO is less relevant in practical photography than is the photographic DR. I used Emil's method (http://www.luminous-landscape.com/forum/index.php?topic=42158.0) to determine the photographic DR at various noise floors for the D800 and the D4, using the DXO full SNR data. The DRs are normalized for the pixel count using the DXO method. As expected, the D800 has better DR at base ISO and the D800 is better at high ISO. The differences are less pronounced at higher noise floors due to the lesser contribution of read noise.
The DR advantage of the D4 at higher ISOs is minor, around 0.5 EV. IMHO, one should choose between these two cameras on factors other than DR.
Regards,
Bill
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The 18% SNR data are a useful start, and for good modern sensors like the D800(E) these seem to be dominated by photon shot noise up to very high ISO speeds, but I would expect sensor noise to become relevant about three stops lower if one also looks at noise down to some moderate-to-deep shadow level.
My point earlier was that if the 18% SNR is dominated by shot-noise, I would guess that there is little to differentiate different cameras as long as one keeps the lense and sensor size variables constant?
So what an 18% SNR measurement may tell us is that having plenty of light, good large-aperture lenses and a large sensor is a good thing. Am I missing something?
-h
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My point earlier was that if the 18% SNR is dominated by shot-noise, I would guess that there is little to differentiate different cameras as long as one keeps the lense and sensor size variables constant?
So what an 18% SNR measurement may tell us is that having plenty of light, good large-aperture lenses and a large sensor is a good thing. Am I missing something?
There is for now at least the likelihood that 18% SNR is not dominated by shot noise at all ISO speeds for all current "interchangeable lens cameras" [ILCs], and that noise generated within the camera (everything except shot noise) starts to make a visible difference in moderately deep shadows even at just moderately high ISO speeds, where the 18% SNR is still dominated by photon shot noise. Even if the visibly relevant shadow regions are only relevant down to about "zone 3", two stops below mid-tones, this "camera noise" could become significant about two stops lower in the ISO speed scale.
But maybe sensor technology is approaching the point where 18% SNR is dictated by basic physics, not the limits of the technology. (Once Canon and the MF industry get their acts together!)
Apart from that, you are perhaps overlooking the cases (see my added emphasis above):
- when one does _not_ have plenty of light
- when the desire for a lightweight, mobile walking/hiking kit rules out large-aperture lenses as anoise-reduction strategy
- when the desire for substantial depth of field makes large apertures unusable.
P. S. Once a large enough lens delivers a certain effective aperture size (entrance pupil diameter) is achieved, sensor size does not matter to photon shot noise in light-limited, high ISO speed situations: a larger sensor with a lens of equal effectively aperture size used with equal exposure duration gives about the same photon signal and noise statistics, just at a higher f-stop and higher exposure index. Larger sensors only help with noise through:
- enabling the use of larger lenses with larger aperture diameters (a given aperture diameter being achievable at less low f-stops), and
- allowing the gathering more photons when using base ISO speed and "full exposure" of the sensor is possible.
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Bob: "Nowhere, nowhere did I say that people weren't able to properly use data."
In addition, too many people tout the hype of the test numbers without inquiry. DxO Mark's headline test numbers for the D800/e are terrific. But those numbers are massaged. How many people actually realise that? I'd venture it's a minority.
Hmmmm ... kinda seems like ya did ...
Gobble, gobble! :o :o
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Although there are situations where extreme DR is important (like scenes of unusually high Subject Brightness Range or forgetting to set the ISO speed appropriately when photographing moths at dusk), I would say that the vast majority of photography involves not much more that the traditional "normal" SBR of about three stops either side of mid-tones.
You're probably right in that respect, BJL. The vast majority of photography is now done with an iPhone or iPad, followed by the so-called P&S camera which in turn is followed by the cropped-format DSLR. The full-frame DSLR seems to be a relative rarity.
Unfortunately perhaps, I'm not one who bases his standards on the practice of the majority. The nature of much my photographic activity is to strive to capture as much detail as possible in the scenes I'm photographing, so that I have a wider creative scope when later processing the image back home on my calibrated system.
Each to his own. Most people seem to be most interested in photographing their friends and loved ones standing in front of any object or scene that's worth photographing in its own right, hence the development of automatic face detection in autofocussing.
I'm more interested in taking notes of a scene that interests me, and a high resolution, high DR, high SNR camera is the best note-taker that I know.
As an example, I recently attended a Thai boxing performancen (I'm currently travelling in Thailand), even though I'm not much interested in the activity of two men attempting to inflict brain damage upon each other.
I did my best to get some interesting shots of a gloved fist smashing into a face, using my D800E with attached flash unit, but it was very much a case of 'hit and miss'.
When I later reviewed my shots after downloading to my Dell Notebook, I noticed that quite often the activity of the boxers was less interesting than the expressions on the faces of the audience on the other side of the ring. I saw expressions of joy, elation, disgust and total boredom, right next to each other, as seen through the V shape of a boxer's legs.
However, and it's a big 'however', such faces were partially beyond the reach of the flash. They were significantly underexposed. But never mind, or 'Mai Bpen Rai' as they say in Thailand. I have a D800E. I can make something of those crops through the boxer's legs because my camera captures detail in the shadows. If I were still using my much revered Canon 5D, I'd be stuffed; deleted image.
Another source of confusion I'd like to address is the notion that 'engineering DR specifications' are not relevant to practical photography, and that the 14EV DR claims of certain Nikon camera, from DXO measurements are no more than engineering specifications.
It's surely not difficult to appreciate that any camera, whatever its DR specification, will not produce 'nice' images within the region of the limits of its dynamic range.
All cameras, whether iPhone, P&S, or DSLR will produce crap photos at the engineering limits of their dynamic range.
The D800, 14 stops down from an ETTR exposure at base ISO, produces crap images, far worse than my underexposed shot of the world's largest moth, I have no doubt.
The issue is this, if I can use an analogy with my only other functioning full-frame camera, the Canon 5D. The 5D has a claimed 11 stop DR by DXO. The D800E has more than 14 stops, at print. Let's call it a 3 stop difference.
Surely it's understood that both the D800 in its 14th stop, and the 5D in its 11th stop produce unacceptable image quality. There's not much point in complaining or arguing that the 14th stop, in the case of the D800, and the 11th stop in the case of the 5D, is of little photographic quality. We all should know that.
The point is, if the scene has an 11 stop dynamic range, how do the cameras compare?
In the 11th stop, the 5D image is crap because that's its engineering limit. However, in the 11th stop the the D800 image is very presentable because that's 3 stops down from its enineering limit. Got it?
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Almost right Ray, but some cameras clip better than others.
And some exhibit banding, others not !
I found my old G10 or my EOS400D give better images than my RX100 when clipping occurs in pools or rivers for example.
But RX100 clips better @ISO125 than @ ISO80.
That's why I always set it @ISO125 or auto ISO (125 to 800) when using it in JPG.
Thierry
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Hi Ray,
I don't think that anybody here says that DR is unnecessary or undesirable, just that most subjects fit in a narrower tonal range. Obviously there are cases where extended DR is helpful.
I don't see any contradiction between good SNR18% and good DR. My impression is that the D800 excels in both areas. To that you can add 36 MP and the choice of OLP filter or not.
Best regards
Erik
You're probably right in that respect, BJL. The vast majority of photography is now done with an iPhone or iPad, followed by the so-called P&S camera which in turn is followed by the cropped-format DSLR. The full-frame DSLR seems to be a relative rarity.
Unfortunately perhaps, I'm not one who bases his standards on the practice of the majority. The nature of much my photographic activity is to strive to capture as much detail as possible in the scenes I'm photographing, so that I have a wider creative scope when later processing the image back home on my calibrated system.
Each to his own. Most people seem to be most interested in photographing their friends and loved ones standing in front of any object or scene that's worth photographing in its own right, hence the development of automatic face detection in autofocussing.
I'm more interested in taking notes of a scene that interests me, and a high resolution, high DR, high SNR camera is the best note-taker that I know.
As an example, I recently attended a Thai boxing performancen (I'm currently travelling in Thailand), even though I'm not much interested in the activity of two men attempting to inflict brain damage upon each other.
I did my best to get some interesting shots of a gloved fist smashing into a face, using my D800E with attached flash unit, but it was very much a case of 'hit and miss'.
When I later reviewed my shots after downloading to my Dell Notebook, I noticed that quite often the activity of the boxers was less interesting than the expressions on the faces of the audience on the other side of the ring. I saw expressions of joy, elation, disgust and total boredom, right next to each other, as seen through the V shape of a boxer's legs.
However, and it's a big 'however', such faces were partially beyond the reach of the flash. They were significantly underexposed. But never mind, or 'Mai Bpen Rai' as they say in Thailand. I have a D800E. I can make something of those crops through the boxer's legs because my camera captures detail in the shadows. If I were still using my much revered Canon 5D, I'd be stuffed; deleted image.
Another source of confusion I'd like to address is the notion that 'engineering DR specifications' are not relevant to practical photography, and that the 14EV DR claims of certain Nikon camera, from DXO measurements are no more than engineering specifications.
It's surely not difficult to appreciate that any camera, whatever its DR specification, will not produce 'nice' images within the region of the limits of its dynamic range.
All cameras, whether iPhone, P&S, or DSLR will produce crap photos at the engineering limits of their dynamic range.
The D800, 14 stops down from an ETTR exposure at base ISO, produces crap images, far worse than my underexposed shot of the world's largest moth, I have no doubt.
The issue is this, if I can use an analogy with my only other functioning full-frame camera, the Canon 5D. The 5D has a claimed 11 stop DR by DXO. The D800E has more than 14 stops, at print. Let's call it a 3 stop difference.
Surely it's understood that both the D800 in its 14th stop, and the 5D in its 11th stop produce unacceptable image quality. There's not much point in complaining or arguing that the 14th stop, in the case of the D800, and the 11th stop in the case of the 5D, is of little photographic quality. We all should know that.
The point is, if the scene has an 11 stop dynamic range, how do the cameras compare?
In the 11th stop, the 5D image is crap because that's its engineering limit. However, in the 11th stop the the D800 image is very presentable because that's 3 stops down from its enineering limit. Got it?
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RX100 clips better @ISO125 than @ ISO80.
That's why I always set it @ISO125 or auto ISO (125 to 800).
Thierry
125 is the base ISO of the RX 100. 80 and 100 are 'fake' ISOs.
... Mine got wet and has died ... :-(
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125 is the base ISO of the RX 100. 80 and 100 are 'fake' ISOs.
That doesn't appear to be true, Jeremy. If you check the DXOMark graphs, you'll see that at ISO 80 all specs are highest for the RX100. At ISO 100 DR is about 0.25 stops worse and at ISO 200 over 1/2 a stop worse. Same applies to SNR, Tonal Range and Color Sensitivity.
I can't think of any reason why Thierry would think that the RX100 clips better at ISO 125, unless he's using in-camera jpeg processing, or some RAW converter that is imposing its own peculiarities.
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I don't think that anybody here says that DR is unnecessary or undesirable, just that most subjects fit in a narrower tonal range. Obviously there are cases where extended DR is helpful.
Hi Erik,
Glad to hear it, but I sense some confusion here. Are you saying that most subjects before they are photographed fit in a narrower tonal range, that is, they have a fairly low SBR, such as indoor scenes, or outdoor scenes on a dull day; or do you mean that most subjects are photographed in such a way, and subsequently processed in such a way, that they are made to fit in a narrower tonal range, whether on print or screen?
The very fact that many camera models now have a built-in HDR feature, and image processing programs like Photoshop include a Merge to HDR facility, and many stand-alone programs exist that are designed specifically for creating HDR images, would tend to suggest that a lot of scenes do not fit into that fairly narrow tonal range that you and BJL describe.
My own experience also suggests that most subjects do not fit into that fairly narrow tonal range, but that may be because I'm an outdoor type of person and live in a country which is blessed with many days of sunshine throught the year. Those who live in the UK, or some northern European country where the sun shines for only two days each year, may be quite satisfied with the low DR capability of their camera. (I may be exaggerating just a bit. I believe St Petersberg has on average as many as 65 days of sunshine per year. ;D )
Having been involved in photography as an amateur since I was a youngster, I recollect frequently over the years seeing blown skies in the photos people have shown me.
When the first reasonably affordable DSLRs appeared on the market, I recall much discussion about the limited DR of these new cameras compared with film. I recall figures such as 5 to 6 stops of DR for slide film, 7 to 8 stops for color negative, and 9 to 11 stops for B&W film. I recall the Canon D60 had a DR not much better than that of slide film.
In those days we didn't seem to use the concept of defining DR in relation to a normalised, fixed size image or print. Was that DR specification of B&W film a property of the average size of the partcles of light-sensitive chemicals on the film surface, analagous to a pixel? If so, there would be a huge difference in DR between the average 35mm format of the day and the 8"x10" format preferred by Ansel Adams, using the same B&W film type.
If we make an assumption that the best, finest grain, B&W film of the day, in 35mm format, had a DR of 11 stops, then a large-format field camera holding the same type of film would surely have had a significantly higher DR than 11 stops.
Whether that's true or not, I simply don't know. It may be the case that only SNR at 18% followed that rule of approximately one stop improvement for each doubling of film area, and that any increases in DR with film format size are compromised by some other limitation.
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That doesn't appear to be true, Jeremy. If you check the DXOMark graphs, you'll see that at ISO 80 all specs are highest for the RX100. At ISO 100 DR is about 0.25 stops worse and at ISO 200 over 1/2 a stop worse. Same applies to SNR, Tonal Range and Color Sensitivity.
I can't think of any reason why Thierry would think that the RX100 clips better at ISO 125, unless he's using in-camera jpeg processing, or some RAW converter that is imposing its own peculiarities.
Just have a look, here http://www.dpreview.com/reviews/sony-cybershot-dsc-rx100/11
Completely different of DXOMark graphs !
Who to trust in ?!!
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That doesn't appear to be true, Jeremy. If you check the DXOMark graphs, you'll see that at ISO 80 all specs are highest for the RX100. At ISO 100 DR is about 0.25 stops worse and at ISO 200 over 1/2 a stop worse. Same applies to SNR, Tonal Range and Color Sensitivity.
I can't think of any reason why Thierry would think that the RX100 clips better at ISO 125, unless he's using in-camera jpeg processing, or some RAW converter that is imposing its own peculiarities.
Check the specs:
http://www.dpreview.com/reviews/sony-cybershot-dsc-rx100
http://store.sony.com/p/Sony-Cyber-shot-DSC-RX100-Camera/en/p/DSCRX100/B#specifications
Also, the in-camera menu identifies 80 & 100 as "expanded" ISOs that are different than 125 to 6400.
Lastly, the specs on the DXO site:
http://www.dxomark.com/index.php/Publications/DxOMark-Reviews/Sony-DSC-RX100-Review/Preview
Everything I have seen first hand and on the web indicates an ISO range of 125-6400.
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Hi,
DPreview data is JPEG and DxO-mark is raw data.
Best regards
Erik
Just have a look, here http://www.dpreview.com/reviews/sony-cybershot-dsc-rx100/11
Completely different of DXOMark graphs !
Who to trust in ?!!
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Everything I have seen first hand and on the web indicates an ISO range of 125-6400.
Everything except the actual measurements of the RAW data from a bunch of meticulous scientists with PhDs, at DXO.
I think Erik may have hit the nail on the head. In-camera jpegs have always, unavoidably and necessarily, been processed in accordance with some esthetic, or merely practical decision made by the designers of the camera.
Just recently during the furore over comparisons between the Canon 5D3 and the D800, Canon fanboys, feeling a bit let down by the possibility that Nikon had produced a better value and better performing camera, would display out-of-camera jpegs from the 5D3 which showed noticeably less noise than similar shots from the D800 at the same high ISO, thus demonstrating that Canon's jpeg engine applied more noise reduction than Nikon's.
For those who shoot in RAW mode, the measurements at DXOMark are a remarkably accurate guide as to what to expect from a camera.
Nevertheless, it's possible that DXOMark may occasionally publish mistakes. I'm still a bit puzzled, just a bit, as to why their graph for the ISO Sensitivity for the Canon 50D implies that ISO 100 on the 50D is an expanded ISO and that the real base ISO is 200. I noticed the figures at DXOMark after I'd been using the camera for some time, often compromising on shutter speed or DoF by using ISO 100 for the sake of better SNR, rather than ISO 200 which I now realise would have been a better choice.
Could it be what DXOMark is really saying is that, although ISO 100 is the official base ISO for this camera according to Canon, our tests indicate that the differences in performance between ISO 100 and 200 are so small that they lie within the margin of error of our measurement techniques.
I'm assuming this is probably the case because my own tests comparing identical, high contrast scenes, shot at ISO 100 and ISO 200, using half the shutter speed for an ETTR at ISO 200, indicate no discernible difference in DR (or shadow detail), and only the slightest difference in SNR at 18%, noticeable at 400% on monitor or print, but invisible at 100%.
In other words, for all practical considerations, ISO 200 is the true base ISO for the Canon 50D, despite what the Canon manual may imply, and that is something which is useful to know. The only reason to use ISO 100 would be for the sake of a slow shutter speed.
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Thanks for those infos, Ray :)
I'm also puzzelled by ISO Sensitivity graphs of almost all MF cameras at DXOMark.
Horizontal ??? ::), what does it really mean in thoses cases ?!
Have a Nice day.
Thierry
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Hi,
DxO describes the ISO standard here: http://www.dxomark.com/index.php/About/In-depth-measurements/Measurements/ISO-sensitivity
Please note that the ISO standard gives only one figure for ISO and that figure is based on sensor saturation.
Some cameras have adjustable gain. All Canons and many Nikons belong to that category. Another solution is to not have variable gain just adjust exposure but tag the raw image with exposure correction. I guess that is exactly what "ISO-less" cameras do.
If you check out the DR graphs on DxO mark you can see that some cameras have essentially a straight line, with DR dropping linearly with ISO. That essentially means ISO-less design. An ISO-less design means that you can achieve the same result with say three stops of underexposure as using 8X times higher ISO.
If all this sounds gibberish, that's OK. The descriptions at DxO are not complete, in my humble opinion.
Best regards
Erik
Thanks for those infos, Ray :)
I'm also puzzelled by ISO Sensitivity graphs of almost all MF cameras at DXOMark.
Horizontal ??? ::), what does it really mean in thoses cases ?!
Have a Nice day.
Thierry
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Glad to hear it, but I sense some confusion here. Are you saying that most subjects before they are photographed fit in a narrower tonal range, that is, they have a fairly low SBR, such as indoor scenes, or outdoor scenes on a dull day; or do you mean that most subjects are photographed in such a way, and subsequently processed in such a way, that they are made to fit in a narrower tonal range, whether on print or screen?
I assume that he is talking about the "subjective DR" of the scene. I.e. the distance between the darkest interesting things in a scene and the brightest interesting things in a scene.
The very fact that many camera models now have a built-in HDR feature, and image processing programs like Photoshop include a Merge to HDR facility, and many stand-alone programs exist that are designed specifically for creating HDR images, would tend to suggest that a lot of scenes do not fit into that fairly narrow tonal range that you and BJL describe.
I think that your argument is good. I will provide an alternate angle nonetheless.
When photographers talk about "HDR", they often mean two things at once, but occasionally one or the other: 1)Synthesizing an image from exposure brackets, 2)Tonemapping an image to reduce its dynamic range. The popularity of HDR _could_ be partially interpreted as a desire among photographers to produce that "dramatic look" of tonemapping, irrespecitve of the scene DR or their cameras DR.
This is similar to how the CD format allows for a DR of 96dB, yet most popular music exploit only a small fraction of that - mastering producers squeeze and clip away all of the life from the music in order for it to sound loud or "catchy" or whatever. The irony is that some music lovers are turning to vinyl - not because of its inherent qualities but because the content put onto vinyl may tend to be less damaged by hearing-damaged producers.
My own experience also suggests that most subjects do not fit into that fairly narrow tonal range, but that may be because I'm an outdoor type of person and live in a country which is blessed with many days of sunshine throught the year. Those who live in the UK, or some northern European country where the sun shines for only two days each year, may be quite satisfied with the low DR capability of their camera. (I may be exaggerating just a bit. I believe St Petersberg has on average as many as 65 days of sunshine per year. ;D )
I believe that partially cloudy/sunny scenes (like we have in my part of the world) can have a substantial subjective DR.
I recall the Canon D60 had a DR not much better than that of slide film.
Yet people shot slide film?
I think that it is hard to compare the DR of film vs digital. It has been tried many times, and the worlds internet users cannot seem to agree.
-h
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If all this sounds gibberish, that's OK. The descriptions at DxO are not complete, in my humble opinion
I am so glad YOU said this. It almost seems to me as I read it that I have new questions that go unanswered, and some of it seems difficult to discren meaning. sensorgen.info seems to make sense to me in terms of interpretation of how the whole camera actually works, but isn't quite as up to date as some of DxO's info.
What are your thoughts on sensorgen?
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Everything except the actual measurements of the RAW data from a bunch of meticulous scientists with PhDs, at DXO ...
... Nevertheless, it's possible that DXOMark may occasionally publish mistakes.
Strange. Hadn't seen that data.
But something weird is going on here ... They don't seem to test 125, but they do 80 and 100 ... BUT nobody refers to those settings as anything other than "extended" ISOs. They aren't included in Program mode or Auto ISO.
This may be one of 'those' cases where the science just wasn't convenient for the marketing folks.
I will care more if Amex decides to give me purchase protection on my unit that got soaked ...
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Hi,
The info given by DxO is probably a good description of the ISO standard. The problem is that the standard described is based on sensor saturation, also known as the full well capacity (FWC). So what DxO says is that ISO is based on sensor saturation. But, sensor saturation would only occur at base ISO. When you increase ISO, underexposure will result, but how are you calculating ISO then?
Some MFDBs show normal ISO curves while some don't.
If you compare Hasselblad and Phase One curves enclosed it is obvious that DR curves are quite a bit similar but ISO curves are very dissimilar.
I'm pretty sure that the underlying data is consistent but I have difficulty in making sense of the presentation of ISO, especially if DxO-s discussion of the ISO standard is taken into account.
Best regards
Erik
I am so glad YOU said this. It almost seems to me as I read it that I have new questions that go unanswered, and some of it seems difficult to discren meaning. sensorgen.info seems to make sense to me in terms of interpretation of how the whole camera actually works, but isn't quite as up to date as some of DxO's info.
What are your thoughts on sensorgen?
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Hi,
The info given by DxO is probably a good description of the ISO standard. The problem is that the standard described is based on sensor saturation, also known as the full well capacity (FWC). So what DxO says is that ISO is based on sensor saturation. But, sensor saturation would only occur at base ISO. When you increase ISO, underexposure will result, but how are you calculating ISO then?
Hi Erik,
Cutting the exposure signal inhalf, and applying double the ISO setting, should result in the same Raw signal level when ISO controls the ADC gain (within the statistical probability of shot noise+readnoise). Any deviation in the Raw signal level is recorded as ISO deviation.
For truely ISO-less sensors (no ADC gain control by the ISO setting) that doesn't work, the signal will be half as well.
Some MFDBs show normal ISO curves while some don't.
That means that some are not truely ISO-less.
Cheers,
Bart
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... It almost seems to me as I read it that I have new questions that go unanswered, and some of it seems difficult to discren meaning...
DXO is French. They think in French, they speak it, and then it is translated to English. As the saying goes, something always gets lost in translation. Me thinks (in English... I think) ;)
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Strange. Hadn't seen that data.
But something weird is going on here ... They don't seem to test 125, but they do 80 and 100 ... BUT nobody refers to those settings as anything other than "extended" ISOs. They aren't included in Program mode or Auto ISO.
This may be one of 'those' cases where the science just wasn't convenient for the marketing folks.
I will care more if Amex decides to give me purchase protection on my unit that got soaked ...
I've made a lot of tests this afternoon, and now I've understood almost everything.
So, I've made manual shots (@f3.5) of a colorchecker, 1st 1/4s @ISO80, 2nd 1/5s @ISO100, 3rd 1/6s @ISO125.
All shots are properly exposed (ETTR) and need only a slight correction (max 0.1Ev) to obtain exactly same exposure in LR4.2.
Results: RAW with same exposure exhibit more noise @ISO100 and even more @ISO125, so DXOMark DR results are correct !
JPG doesn't need any exposure correction, exposure really identical, but it's clear that ISO125 is progressively compressed in the highlights, but neither ISO80, nor ISO100, so DPReview results are correct too !
So, if you shoot RAW, use ISO80 if it's possible.
Also noticed that the 2 last patches of my colorcheker were blinking (@ISO80 and 100), but RAW data were not clipped !!!
Have a Nice Day.
Thierry
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From the Full SNR curve, you can read DR and SNR18%.
Is that right ???
Another question, with LR or DXO, what's the SNR possible improvement (in dB) without significant loss of resolution ?!
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Hi,
In my view your interpretation of DR is wrong.
The other question is tricky, the best answer I can give is a lot if you combine sharpening, masking and noise reduction.
Best regards
Erik
From the Full SNR curve, you can read DR and SNR18%.
Is that right ???
Another question, with LR or DXO, what's the SNR possible improvement (in dB) without significant loss of resolution ?!
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Everything except the actual measurements of the RAW data from a bunch of meticulous scientists with PhDs, at DXO.
After some further investigation ...
How would you interpret this data, Ray?
http://home.comcast.net/~NikonD70/Charts/PDR.htm
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I appreciate all the knowledge to be gained about digital images here as there are so many here with so much to share. But of course comparing graphs is far more boring than actually testing for oneself. Further, though manufacturers try to maintain strict control, it has been my experience with very sophisticated electronic equipment that there is some sample to sample variation. So while comparing DxO, senseorgen and comcast data is intriguing, it may be time to evaluate for myself.
I have a D4 and love it. It really takes pictures in the dark. But am contemplating a D800e or perhaps a D600 for a lighter weight alternative and the advantage to having a lens already mounted. Beside that, the 800e would allow me to be a "Big Cropper" when a long tele is unavailable. (is this a great time to be a photographer or what?).
So took a series of photos with the lens cap on, all 1 sec exposures at every ISO rating, all in LR 4.2. When contrast is pushed to 100 and 1:1 there is very little noise up to 3200 (as in almost none), at 6400 I can see a bit, but noting really until 25200 and even then not much. Only when we go above that is there much to see. 50K is still pretty good, but 102K and 204K is noticeably more.
If exposure is pushed the noise is far more evident but not sure how much is LR artifact so maybe that's not a good comparison.
Could some of you more experienced and educated folks tell me how to establish where the "knee" is where adding ISO is detrimental? And perhaps how to discern the point where it becomes "ISO Max" as far as image quality goes?
Thanks, as always...
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From the Full SNR curve, you can read DR and SNR18%.
Is that right ???
Thierry,
The Full SNR curve is revealing but I get the impression that it applies spefically to the pixel without regard to sensor size, so for example, the Full SNR curve for the D800 will be almost identical to the Full SNR curve for the D7000, but in photographic images of the same scene the D800 will exhibit noticeably better SNR.
In your example in attached image showing a vertical red line on the right indicating DR, you've missed out the necessary red line on the left of the graph to indicate the range. Dynamic Range is a range, from the brightest highlights that contain detail, to the darkest shadows that contain detail.
In the Full SNR log graph you have shown, 0.1% grey on the horizontal axis, and less, would represent the deep shadows, and this is where the men are separated from the boys. ;D
The rather large pixel of a camera like the Canon 5D has an SNR of about 5dB at 0.1% grey, whereas the much smaller pixel of the Nikon D800 has an SNR of about 16dB at 0.1% grey, a vast improvement. The fact that the D800 sensor has many more pixels than the 5D, increases that advantage even further at equal image size.
Another question, with LR or DXO, what's the SNR possible improvement (in dB) without significant loss of resolution ?!
I've got no idea, Thierry. When I process my images, I use my eyeballs to determine what is acceptable noise and acceptable resolution.
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After some further investigation ...
How would you interpret this data, Ray?
http://home.comcast.net/~NikonD70/Charts/PDR.htm
The data seem to be broadly in line with DXOMark's results, Jeremy. Shadow noise that is photographically acceptable will inevitably be a subjective opinion, but I think most people would agree that noise at the engineering limit of DR, such as noise in the 14th stop for the D800, or noise in the 11th stop for the canon 5D, is unacceptable.
The following graph indicates that the D800e has a 'Photographic DR' of 11.5 stops, about 3 stops down from the engineering DR which is described at DXOMark as over 14 stops. The Canon 5D has a PDR of about 8.25 stops which is close to 3 stops down from the DXO rating of a fraction over 11 stops.
The only surprise is the difference between the D7000 and the D800E. At equal image sizes (print mode on the graphs), the D800 has an advantage of close to 1/2 a stop, according to DXOMark, whereas the PDR graph shows an advantage of over one full stop.
Whatever the explanation for such a difference, it would tend to fit with the surprise I experienced when processing the underexposed shot of the moth.
Perhaps someone more technically orientated than my self can provide an explanation. I'm really just a simple guy trying to get the best visual quality from the scenes I capture. ;D
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The data seem to be broadly in line with DXOMark's results, Jeremy.
I meant about the RX100 ... it isn't quite the same as DXOMark it would seem.
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Hi,
I essentially agree with Ray's explanation. 'Photographic DR' has a different interpretation from the normal one used in engineering. DR is normally based on SNR=1 condition. My guess is that it is at this level that signal is discernible from noise. My understanding/presumption is that 'Photographic DR' is simply based on another threshold, like SNR=8, that is signal 8 times stronger than noise.
Now, the normal DR is defined as FWC/read noise. There is another factor affecting noise and that is shot noise. Shot noise is a property of light. If you collect more light, the noise will be less. When you move the threshold for DR to stronger SNR ratios, it also mean that shot noise will be more dominant.
Making either the sensor larger or increasing the full well capacity of the pixels will reduce shot noise.
If you are really interested in noise behavior, this article is an excellent read: http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html
Best regards
Erik
The data seem to be broadly in line with DXOMark's results, Jeremy. Shadow noise that is photographically acceptable will inevitably be a subjective opinion, but I think most people would agree that noise at the engineering limit of DR, such as noise in the 14th stop for the D800, or noise in the 11th stop for the canon 5D, is unacceptable.
The following graph indicates that the D800e has a 'Photographic DR' of 11.5 stops, about 3 stops down from the engineering DR which is described at DXOMark as over 14 stops. The Canon 5D has a PDR of about 8.25 stops which is close to 3 stops down from the DXO rating of a fraction over 11 stops.
The only surprise is the difference between the D7000 and the D800E. At equal image sizes (print mode on the graphs), the D800 has an advantage of close to 1/2 a stop, according to DXOMark, whereas the PDR graph shows an advantage of over one full stop.
Whatever the explanation for such a difference, it would tend to fit with the surprise I experienced when processing the underexposed shot of the moth.
Perhaps someone more technically orientated than my self can provide an explanation. I'm really just a simple guy trying to get the best visual quality from the scenes I capture. ;D
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On second thoughts, I think I've got it! ;)
DXOMark on their DR graph are describing the outer limits of the dynamic range at each ISO, whereas the Photographic DR describes the SNR over a range from photographically acceptable shadows, at a chosen minimum SNR of 20dB, to the non-blown highlights. Over that entire range, the improved SNR of a sensor such as the D800, which is a bit more than twice the size of the D7000 sensor, should be on average a bit over 3dB better, which translates to a bit over one stop better.
In parts of the scene where SNR is less than 20dB, which might be considered as photographically unacceptable, the SNR advantage of the D800 dimishes to the point where, at the engineering limit or around 14 stops, it is a bit less than 1/2 a stop better than the D7000, as DXOMark describe it.
Everyone agree? ;D
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I meant about the RX100 ... it isn't quite the same as DXOMark it would seem.
Oh, I see! You mean this oddity where the RX100 seems to have the same PDR at ISO 125 as it does at ISO 80, and DR is worse at ISO 100 than it is at ISO 125 when one would expect it to be at least as good if not marginally better.
Sorry! I have no explanation for this. Maybe Bart or Bill Claff can help. Since you no longer have the camera, it's not possible for you to check this for yourself, but Thierry seems to have done so. This is what he wrote.
So, I've made manual shots (@f3.5) of a colorchecker, 1st 1/4s @ISO80, 2nd 1/5s @ISO100, 3rd 1/6s @ISO125.
All shots are properly exposed (ETTR) and need only a slight correction (max 0.1Ev) to obtain exactly same exposure in LR4.2.
Results: RAW with same exposure exhibit more noise @ISO100 and even more @ISO125, so DXOMark DR results are correct !
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Very interresting thread !!
Thanks Erik and Ray !
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Oh, I see! You mean this oddity where the RX100 seems to have the same PDR at ISO 125 as it does at ISO 80, and DR is worse at ISO 100 than it is at ISO 125 when one would expect it to be at least as good if not marginally better.
It would seem to contradict the DXO data ... and would seem to be in-line with the specs reporting a 125-6400 true ISO range.
I will prolly get another ... But not until I find out if AMEX will replace mine ... Which I'm thinking they will.
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From the Full SNR curve, you can read DR and SNR18%.
Is that right ???
Another question, with LR or DXO, what's the SNR possible improvement (in dB) without significant loss of resolution ?!
Your interpretation of DR is not correct. The vertical line at 100% shows the SNR at sensor saturation or clipping in the ADC for various ISOs. The DR is the ratio between the brightest part of the image (100%) and the darkest part of the image with a given SNR (the noise floor). At base ISO the engineering DR as determined by DXO places the noise floor at a SNR of 0 dB or 1:1 (green vertical bar). The percent saturation at this noise floor with your example is 0.0291% and the DR is 100%/0.0291% or 11.75 stops. If you place the noise floor at 12 dB (4:1) as shown by the red bar, the percent saturation at that SNR is 0.336% or 8.22 stops.
The methodology for these determinations is explained by Emil (http://www.luminous-landscape.com/forum/index.php?topic=42158.0). The difficult part is with log interpolation (http://en.wikipedia.org/wiki/Logarithmic_scale) of the graph value.
Regards,
Bill
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It would seem to contradict the DXO data ... and would seem to be in-line with the specs reporting a 125-6400 true ISO range.
I will prolly get another ... But not until I find out if AMEX will replace mine ... Which I'm thinking they will.
Not really. DXO don't show test results for the intermediate ISOs. They test base ISO then at increments of one stop from ISO 100. If you remove the PDR result at ISO 125, the shape of the graph approximates DXOMark's graph for DR. The jump in DR performance at both ISO 80 and ISO 125, or the dip in performance at ISO 100, looks very odd to me.
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Many Thanks Bill !!
It's more clear now ;)
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Has anyone taken time to study the thermal noise characteristics of the D800/E and how best to mitigate them? In my view, this is the only thing standing in the way of this camera being usable at the highest gain settings.
A simple black frame subtraction will go a long way, and LENR is mandatory. What I think though is that LENR should be a full-time option on this camera. I see abundant thermal noise at ISO6400 and a handheld shutter speed (1/80th).
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You're probably right in that respect, BJL. The vast majority of photography is now done with an iPhone or iPad, followed by the so-called P&S camera which in turn is followed by the cropped-format DSLR. The full-frame DSLR seems to be a relative rarity.
Let me clarify my comments, in the off chance that you genuinely misunderstood me to be talking about photography done with phones and other truly pocketable cameras: what I intended to convey is that a roughly six or seven stop subject brightness range covers the great majority of the sort of photography of interest to readers of these forums. To be a little more specific, this SBR historically covered the great majority of film photography in any common film format and camera type, even if one only considers photography done with SLR's or larger formats. This is made fairly clear by reading the discussions of film photography capture and printing technique in numerous texts on the subject: tools and techniques like graduated ND filters are there, but not needed for the great majority of cases (and seem particularly needed with color transparency film for which six stops of SBR is optimistic). As a mild extrapolation, It seems from my observations that the move to digital cameras has not greatly changed the preponderance of scenes with "normal" SBR.
The rest of you post seems to be a single example of a "scene of unusually high SBR" which I mention in your quote from me above (and a second case in this thread of severely underexposing the subject matter of main interest!) So we agree that such situations exist: my point was that measurements of relevance to the imge quality achieved in the great majority of one's photography are overall more important that measurements relevant only in a small fraction of extreme situations (or errors or afterthoughts in choice of exposure levels). If your photography involves numerous cases of such exposure difficulties, then I can accept that SNR in parts of the scene that would normally be displayed in deep, low detail shadow regions are more important to you than they are to most of us. For my purposes though, I am still far more interested in measurements that indicate how a camera will handle my intended subject matter when roughly correct exposure level is chosen.
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Please note that the ISO standard gives only one figure for ISO and that figure is based on sensor saturation.
Not at all: that is a myth, partly encouraged by DxOMark's quirky use and selective quotation of the relevant ISO standard, number 12232.
In reality the current ISO standard 12232:2006 specified five ways to measure and report a digital camera's sensitivity:
- One based on signal saturation. (This seems primarily intended for measuring minimum usable exposure index and maximum usable exposure levels, and is related to "base-ISO speed" rather than being suited to callibration of the EI settings on a camera, and is what DxOMark's uses at all exposure index levels.)
- Two, called Snoise40 and Snoise10, that measure low-light handling, and are based on the maximum exposure index levels that give SNR levels of 40:1 and 10:1 respectively under specified conditions. (These are more akin to the ISO definition of film speed, but are rarely used, and seem designed to assess maximum usable exposure index, rather than for calibration of EI settings.)
- Two newer ones added in the 2006 update of 12232, "Standard Output Sensitivity" and "Recommended Exposure Index", which relate to the level placement in output after conversion to an sRGB format like JPEG. (These are the only ISO standards that seem directly intended for use in calibrating the EI settings on cameras, and are what most or all camera makers use for this purpose, in part due to a requirement to do so from the Japanese industry association CIPA, which originated these two standards before their adoption by the ISO.
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Hi,
Thanks for putting things right!
Best regards
Erik
Not at all: that is a myth, partly encouraged by DxOMark's quirky use and selective quotation of the relevant ISO standard, number 12232.
In reality the current ISO standard 12232:2006 specified five ways to measure and report a digital camera's sensitivity:
- One based on signal saturation. (This seems primarily intended for measuring minimum usable exposure index and maximum usable exposure levels, and is related to "base-ISO speed" rather than being suited to callibration of the EI settings on a camera, and is what DxOMark's uses at all exposure index levels.)
- Two, called Snoise40 and Snoise10, that measure low-light handling, and are based on the maximum exposure index levels that give SNR levels of 40:1 and 10:1 respectively under specified conditions. (These are more akin to the ISO definition of film speed, but are rarely used, and seem designed to assess maximum usable exposure index, rather than for calibration of EI settings.)
- Two newer ones added in the 2006 update of 12232, "Standard Output Sensitivity" and "Recommended Exposure Index", which relate to the level placement in output after conversion to an sRGB format like JPEG. (These are the only ISO standards that seem directly intended for use in calibrating the EI settings on cameras, and are what most or all camera makers use for this purpose, in part due to a requirement to do so from the Japanese industry association CIPA, which originated these two standards before their adoption by the ISO.
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Let me clarify my comments, in the off chance that you genuinely misunderstood me to be talking about photography done with phones and other truly pocketable cameras: what I intended to convey is that a roughly six or seven stop subject brightness range covers the great majority of the sort of photography of interest to readers of these forums. To be a little more specific, this SBR historically covered the great majority of film photography in any common film format and camera type, even if one only considers photography done with SLR's or larger formats. This is made fairly clear by reading the discussions of film photography capture and printing technique in numerous texts on the subject: tools and techniques like graduated ND filters are there, but not needed for the great majority of cases (and seem particularly needed with color transparency film for which six stops of SBR is optimistic). As a mild extrapolation, It seems from my observations that the move to digital cameras has not greatly changed the preponderance of scenes with "normal" SBR.
If that's what you mean, BJL, I can only presume it's an assumption based upon the fact that the vast majority of photographic scenes have been captured with devices not capable of capturing even 6 or 7 stops of DR, if one includes 35mm slide film and early photographic B&W plates.
It stands to reason, if one is a photographer trying to make a living with a device that captures no more than 6 stops of photographic dynamic range (PDR), that the vast majority of results will not contain more than 6 stops of DR.
The Graduated Neutral Density filter was always a rather inadequate device bcause the line of graduation would rarely even approximately match the significantly varying, wiggly line that often separates a bright sky from a much darker foreground.
Whilst merging multiple images with different exposures to match what the eye sees when one views a sunlit scene, is now much easier in the digital darkroom, it's not something which lends itselft to critically good results without taking the pains of using a tripod when shooting the limited number of scenes which are truly static, and without taking the trouble to make a good job of the tone-mapping, which is just a fancy word for the processing-compression required of any photographic capture to fit the more limited DR of screen or print.
Whilst I would agree that the majority of scenes that most people actually shoot may not require a camera with a greater PDR than than 6 or 7 stops, I would suggest that's because the majority of shots that people take in general are snapshots of themselves and/or friends standing in front of some interesting or famous artifact, ruin, building, sign etc.
On such occasions, if there happens to be a bright sky in the background, it will be blown. But that's of little consequence since the main interest for them is themselves in association with the famous structure they are partially obscuring.
It seems to me that serious landscape photographers, and let's not forget this is a landscape-orientated site, have always been concerned about the limited dynamic range of their cameras. Didn't Ansel Adams devise the 'Zone System' in an attempt to tackle this issue? Isn't the subject of ETTR one of the most frequently discussed technical issues that's raised again and again, presumably because people sense that their cameras may not be adequate to capture the full PDR of many scenes that they find interesting, unless they maximise exposure without blowing essential highlight detail, and even then perhaps not adequate?
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Not at all: that is a myth, partly encouraged by DxOMark's quirky use and selective quotation of the relevant ISO standard, number 12232.
In reality the current ISO standard 12232:2006 specified five ways to measure and report a digital camera's sensitivity:
- One based on signal saturation. (This seems primarily intended for measuring minimum usable exposure index and maximum usable exposure levels, and is related to "base-ISO speed" rather than being suited to callibration of the EI settings on a camera, and is what DxOMark's uses at all exposure index levels.)
- Two, called Snoise40 and Snoise10, that measure low-light handling, and are based on the maximum exposure index levels that give SNR levels of 40:1 and 10:1 respectively under specified conditions. (These are more akin to the ISO definition of film speed, but are rarely used, and seem designed to assess maximum usable exposure index, rather than for calibration of EI settings.)
- Two newer ones added in the 2006 update of 12232, "Standard Output Sensitivity" and "Recommended Exposure Index", which relate to the level placement in output after conversion to an sRGB format like JPEG. (These are the only ISO standards that seem directly intended for use in calibrating the EI settings on cameras, and are what most or all camera makers use for this purpose, in part due to a requirement to do so from the Japanese industry association CIPA, which originated these two standards before their adoption by the ISO.
BJL,
No-one gives two hoots about these ancient standards of ISO. With modern DSLRs, it's sensor saturation which becomes the standard.
The only issue that is of concern to me is the consistency of DXO's approach and the consistency of their standards. Whether DXO's interpretation of the ISO standard agrees with yours, or anyone elses, is irrelevant. The only issue is the relative ISO sensitivity of the cameras that DXO test. I don't care one whit whether an ISO rating is described as ISO 100 or TWU 254.5. What counts is the sensitivity, in relation to full-well saturation, of one camera compared to another.
I've yet to see any tests which demonstrate that, when DXO claim that camera A requires twice the exposure as camera B, for full well saturation, that this is in fact incorrect.
All those interested in the ETTR concept are interested in what exposure is required for full-well saturation. It's clear that the various ISO definitions of the various manufacturers of cameras differ. According to DXO, most manufacturers exaggerate their ISO sensitivity, which is not surprising. As long as DXO are consistent in their methodology, that's all that's required, because manufacturers are clearly not consistent.
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I've yet to see any tests which demonstrate that, when DXO claim that camera A requires twice the exposure as camera B, for full well saturation, that this is in fact incorrect.
you are not dealing with "wells" - you are dealing with raw files containing the data written there by firmware (and so does DxO) - so just take a proper software like rawdigger and see the raw histogram, that's it...
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According to DXO, most manufacturers exaggerate their ISO sensitivity
not most, just some.
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you are not dealing with "wells" - you are dealing with raw files containing the data written there by firmware (and so does DxO) - so just take a proper software like rawdigger and see the raw histogram, that's it...
I'm not familiar with rawdigger and have no experience whatsoever with it. I you do, and think it demonstrates that DXO's ISO comparisons are inaccurate, then please show us the results so we may discuss them.
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not most, just some.
My experience in relation to the cameras that interest me is, most. It is a rarity that a camera has even nearly the exact ISO specified by the manufacturer. MFDBs are way out. Most Canon and Nikon cameras are somewhat less in ISO sensitivity. It's a rarity to find a camera, such as the Sony RX100, for example, that has a DXO-measured ISO of 101 at its nominated ISO of 100. I also notice that the Panasonic P&S FZ150 has some very accurate ISOs. But such cameras are in the minority.
There are lots of cameras that are significantly less sensitive than the nominated ISO. There are a few that are pretty exact. There are none I've seen that are significantly more sensitive, such as a DXO tested ISO 120, as opposed to the manufacturer's claim of 100.
If I've missed such examples, then please enlighten me. I'm here to learn.
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I'm not familiar with rawdigger and have no experience whatsoever with it. I you do, and think it demonstrates that DXO's ISO comparisons are inaccurate, then please show us the results so we may discuss them.
I'd suggest you to get familiar = http://www.rawdigger.com , it is a nice program that replaced Gabor Schorr's (RIP) one
The test is very simple - get a raw file from a camera where DxO says manufacturer's ("nominal") ISO is less than "measured" ISO and identically exposed (aperture, exposure, etc) raw file from a camera where DxO says manufacturer's ISO is pretty much the same as "measured" ISO, both shot with the same "nominal" ISO set in camera (ISO setting is not a part of exposure)... open both in rawdigger and compare the raw data histograms between both raw files in terms of how close the data is to clipping.
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MFDBs are way out. Most Canon and Nikon cameras are somewhat less in ISO sensitivity.
well, that was exactly what I was talking about - there is a difference between 1) MFDBs where high ISOs are just values in some raw file tag, but raw data is unchanged numbers wise 2) camera's like m43 from Olympus, where you have a constant sensor undersaturation to safeguard highlights for JPEG shooters 3) the rest of the pack that is either exact match or just "somewhat less in ISO sensitivity"
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BJL,
No-one gives two hoots about these ancient standards of ISO. With modern DSLRs, it's sensor saturation which becomes the standard.
"Ancient"?! ISO 12232:2006 Photography -- Digital still cameras -- Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index
http://www.iso.org/iso/catalogue_detail?csnumber=37777
was published in 2006 (as the suffix indicates) and is specifically for digital sensors, not film (as the title states).
Since you are apparently ignorant of this current standard, and buying the full document from ISO is a bit expensive just to try to win an internet forum debate, you could try reading secondary sources like this slideshow presentation from someone who is involved in some of this standards work:
http://www.rps-isg.org/DF2008/DigitalPhotographyStandards.pdf
Even Section 4 of the misleadingly named Wikipedia article
http://en.wikipedia.org/wiki/Film_speed
would help.
You would then learn that if indeed DxO claims that "most manufacturers exaggerate their ISO sensitivity",
then DxO is utterly wrong: instead, most manufacturers are following the current ISO standard, using measurements according to either "Standard Output Sensitivity" or "Recommended Exposure Index", as is in fact required of Japanese camera manufacturers. They are simply not using DxO's preferred choice of equating "more than the standard-specified _minimum_ amount of highlight headroom in raw files" with "overstating the sensitivity".
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I'd suggest you to get familiar = http://www.rawdigger.com , it is a nice program that replaced Gabor Schorr's (RIP) one
The test is very simple - get a raw file from a camera where DxO says manufacturer's ("nominal") ISO is less than "measured" ISO and identically exposed (aperture, exposure, etc) raw file from a camera where DxO says manufacturer's ISO is pretty much the same as "measured" ISO, both shot with the same "nominal" ISO set in camera (ISO setting is not a part of exposure)... open both in rawdigger and compare the raw data histograms between both raw files in terms of how close the data is to clipping.
If the test is so simple, Vladimirovich, why don't you do it and show everyone the results. I'm currently travelling with just one camera, the D800E and two zoom lenses. I don't currently have the time nor the opportunity to carry out such tests, but I will emphasise that whenever I come across anomalies or puzzling aspects of camera performance with my own equipment, that suggest a prevailing or authoritative opinion on performance appears to be incorrect, I do my best to test the issue for myself and report on the results, showing my test images on forums such as LL.
The last series of tests I conducted as a result of what appeared to be some anomaly that I'd observed in DXOMark's ISO sensitivity rating, was in relation to the Canon 50D. DXOMark's ISO Sensitivity curves show this camera to have a base ISO of 200. ISO 100 appears to be an expanded ISO, and therefore DXO does not show any DR, SNR or Tonal Range results for ISO 100.
That seemed very odd to me because Canon make no mention that ISO 100 on the 50D is an expanded ISO. Also, my impression is that expanded ISOs below base ISO tend to lose some aspect of performance and gain in other aspects. For example, if the exposure is double, at an expanded ISO below base, one would expect at least some slight loss of highlight detail, or a greater tendency to clipping of highlights, but also one would expect slightly cleaner shadows and better SNR at 18%.
My tests indicated that there was no image quality difference of any practical significance between an exposure at ISO 100, and 1/2 that same exposure at ISO 200, therefore, from my perspective, the issue was settled. I use ISO 200 on my 50D as though it is base ISO, and get the benefit of a possibly sharper image due to the faster shutter speed. I have DXO to thank for pointing this out, even if, as some claim, a mistake was made on their part.
As I've mentioned before, the value of DXOMark for me is the objectivity and consistency of their results. Whenever I've compared the performance of two or more of my cameras, testing for qualities such as DR and noise, I've never found that DXOmarks relative ISO Sensitivity ratings are wrong. It's the relative values that count for me, because at least I have some control over them. I can decide buy a camera with a higher base sensitivity, which has equal or better performance at that higher sensitivity, if I'm disatisfied.
If you have evidence that DXO's misrepresentation of ISO values, or understatement of them is causing a problem, then please explain why and show us your test results. We might all learn something of benefit to our photography.
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You would then learn that if indeed DxO claims that "most manufacturers exaggerate their ISO sensitivity",
then DxO is utterly wrong: instead, most manufacturers are following the current ISO standard, using measurements according to either "Standard Output Sensitivity" or "Recommended Exposure Index", as is in fact required of Japanese camera manufacturers. They are simply not using DxO's preferred choice of equating "more than the standard-specified _minimum_ amount of highlight headroom in raw files" with "overstating the sensitivity".
That's a very good point, BJL, upon which I think you should amplify. If DXOMark use the terminology, ISO, then the reader would naturally assume that DXO are abiding by the accepted ISO standard, whatever than may be.
If you have discovered that DXO are not abiding by that standard, and have in effect their own standard, and that this is the explanation for the variance between the manufacturer's nominated ISO and DXO measurements, then that's a good point to make.
In itself, the point may be of little practical relevance to the photographer using his camera, but may be of some general interest and could be the subject of a new topic.
If you do decide to raise a new topic on this issue, I have the following questions for points of dicussion, which I would raise in advance.
(1) If DXO are using a slightly different standard than the ISO, is it because they think that their standard is better, or more appropriate within the context of their testing procedures, and/or in relation to the digital medium.
If this is the case, what are the relative merits of the two standards? My guess would be, despite my ignorance, that the true ISO standard is more conservative than DXO's standard, in order to accommodate in-camera jpeg processing which, in my experience, always tends to lose highlight detail.
(2) If DXO are in practice using a different sensitivity standard to ISO, is there perhaps a good reason for their not renaming their standard along the lines of, perhaps, SSSS (Sensor Saturation Sensitivity Standard)?
When placing the cursor over the ISO dot on the DXOMark graph, which produces two readings, the manufacturer-nominated reading of ISO 100 and the DXO measured reading of ISO 87, for example, would it be a good idea for the two readings to be ISO 100 and SSSS 87?
I get the impression that many folks don't go further than the overall, weighted scores for the camera, perhaps because they are a bit intimidated by decibels and EVs. Perhaps DXOMark have decided that such people would be even more intimidated by completely new terms such as SSSS, so they continue to use the widely recognised term ISO which is generally more meaningful.
(3) Does it really matter what standard is used provided that, whatever standard is used, it is consistent? Is that not the only legitimate criticism, a lack of consistency?
When I buy a camera after careful comparison of its specs, my main consideration may be that my choice of camera has a higher base ISO than another, without any compromise in performance with regard to noise and color sensitivity.
Whatever standard is used may be irrelevant as long as the standard is consistent. I don't care if someone gives me a meausrement in centimetres or inches. I can work it out.
Now I hope you can follow this up, BJL, so we can perhaps learn something useful and practical.