Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Salmo22 on November 06, 2010, 06:40:04 pm
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I'm new to the LL forum and returning to serious photography after a long hiatus. While I still have stains on my hands from working in my father's professional darkroom 30+ years ago, I am working hard at getting up to speed on the digital process. I got a copy of D-65's Lightroom Workbook today and have been reading with earnest. Seth/Jame make the statement that "Every digital camera has an optimum ISO setting"; and that "The best capture quality will be obtained using that [optimum] ISO". I've got a 5D MKII on order and would appreciate learning the best method to determine the optimum ISO for my camera. Sorry for the basic question; however, I want to get this right.
Thanks.
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In general, the "optimum ISO" is the native ISO of the sensor, without gain (which increases noise in exchange for sensitivity), or "digital pulling" (which decreases highlight detail in the process of decreasing sensitivity but also reduced noise).
I believe the 5D's native ISO is 100, not 100% sure.
That doesn't mean it's always best to shoot at 100 ISO. Some cameras have "highlight tone priority" or something to increase highlight detail by shooting a stop slower and pushing up dark areas digitally--and that requires a base ISO twice the camera's native ISO (200ISO on the 5D, I think).
Just think about digital ISO as you would with different films': lower is cleaner and more detailed, faster means more flexibility in terms of stopping down or using a faster shutter. In terms of absolute image quality, the "native" ISO is best; in terms of superior images, whatever allows you to get the f-stop/shutter speed combination you need while not looking too noisey is best. And you can shoot up to 3200ISO and still get a great image, though you will notice noise. The 5DII is so good you don't have to worry about shooting everything at a low ISO, as you would with a point and shoot.
Play around with the camera and see what you find acceptable. Despite tons of obfuscating menus and stuff, digital cameras aren't substantially different from film slrs. You may have to adjust your exposure technique over time, though. That said, the image quality should trounce 135. And sick camera, btw. If I had the money that would be my top choice.
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Most digital cameras don't have an optimum ISO setting. Instead, they have two.
At one ISO setting—usually the very lowest, typically ISO 50/18°, ISO 80/20°, or ISO 100/21°, in some cameras called 'pull'—the digital noise is at its optimum. i. e. lowest. At some other ISO setting—usually one or two stops above the lowest, typically ISO 160/23° or ISO 200/24°, in some cameras the lowest that's not marked 'pull'—the dynamic range is at its optimum, i. e. widest. These two optima usually don't coincide. Exceptions to this rule may exist, in particular at very large or very small sensor formats.
Most photographers go for the dynamic-range optimum whenever possible. Here, noise is so low that having even less noise is not considered worthwhile, especially not when it comes at the price of slightly reduced dynamic range. So the 'pull' settings usually get used only as a ND filter substitute rather than for their extra-low noise, when light is too bright for the desired aperture/speed combination at higher ISO settings.
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would appreciate learning the best method to determine the optimum ISO for my camera. Sorry for the basic question; however, I want to get this right.
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From the perspective of a hobbyist, I think that you are going to far into the "weeds" with "best method to determine the optimum ISO for my camera". What is the optimum f/stop?, shutter speed, focal length? ISO?...just another variable to think about to obtain the best image for a particular situation. Enjoy shooting RAW with your new 5D MKII and have fun post processing in LR3.
Steve
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At one ISO setting—usually the very lowest, typically ISO 50/18°, ISO 80/20°, or ISO 100/21°, in some cameras called 'pull'—the digital noise is at its optimum. i. e. lowest. A
My 2c's : this one is not that useful, as these modes usually work only like overexposing at optimum ISO ; so, by exposing to the right at that ISO where dynamic range is highest, the same lowest level of noise is achieved.
Bottom line : to determine optimum ISO, take the maximum of the dynamic range plot of your camera in DxOmark.com.
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From the perspective of a hobbyist, I think that you are going to far into the "weeds" with "best method to determine the optimum ISO for my camera". What is the optimum f/stop?, shutter speed, focal length? ISO?...just another variable to think about to obtain the best image for a particular situation. Enjoy shooting RAW with your new 5D MKII and have fun post processing in LR3.
Steve
Steve:
Thank you for the comments. I apologize for not being more detailed in my question - I will be shooting professionally. I am a private consultant to commercial land developers and they have been requesting that I provide them with photographic services (i.e. construction progress, archtectural, special inspections, etc). They are aware of my history shooting professionally for my father and want me to take care of their needs. Accordingly, I need to get my skills/knowledge updated from my film experiene to digital. This includes adopting best practices for my equipment.
Thanks again.
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My 2c's : this one is not that useful, as these modes usually work only like overexposing at optimum ISO ; so, by exposing to the right at that ISO where dynamic range is highest, the same lowest level of noise is achieved.
Bottom line : to determine optimum ISO, take the maximum of the dynamic range plot of your camera in DxOmark.com.
Nick - I sincerely appreciate the comments. I went to the DxOMark site and (if I read the data correctly) it appears that 100 ISO is optimum. I want to make sure I understand your comments about exposing to the right at optimum ISO. Do you mean that with my 5D MkII I can get the highest dynamic range and lowest noise levels by exposing to the right at ISO 100? Sorry to be dense on this matter; however, I want to make sure I understand.
Thanks.
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Do you mean that with my 5D MkII I can get the highest dynamic range and lowest noise levels by exposing to the right at ISO 100?
That's correct. However, to expose to the right, you need to know that the camera histogram is based on the JPEG thumbnail that's embedded in the Raw fle. That JPEG will not show the real headroom of the Raw data because a tone curve was applied to the JPEG. You'll get a feeling for how it's different when you pay attention during Raw conversion. Just shoot some bracketed exposures and note the JPEG histogram and compare with the Raw histogram.
As far as dynamic range goes, in difficult situations you can also use bracketing and later do exposure fusion or HDR tonemapping. But for now, first concentrate on getting the exposure of a single frame right, the rest will follow from that.
Cheers,
Bart
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Rather than finding absolute numbers, go out and get some shooting time with different iso settings under different lighting conditions. Get a feeling for what works best for you, rather than the numbers. Learn what your camera is capable of producing under different speeds and lighting and you'll be able to master this part of the craft.
You'll learn more than you can from running software generating a bunch of numbers and get more hands-on with your camera, thus get to know it better.
To get a reasonable approximation of what the chip sees, you've got to turn the camera's rendering intent to sRGB, turn down the contrast of the camera display a notch and run it at the normal color intent, not vivid, to get a closer version of what the chip sees. The image will appear flat.
The reason behind this is that your preview image is a rendered jpeg file created by the camera of the raw image. Those settings will skew the preview and thus give you even less accurate version of your final raw file. Since the file you are shooting is raw, color space is irrelevant.
Once in your raw workflow, you can then optimize your image, including setting the master file color space.
Nobody will ever see the numbers behind the image, it's the crafting of the final image for web, print, or otherwise that actually matters!
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Rather than finding absolute numbers, go out and get some shooting time with different iso settings under different lighting conditions. Get a feeling for what works best for you, rather than the numbers. Learn what your camera is capable of producing under different speeds and lighting and you'll be able to master this part of the craft.
I think that advise is the most sensible for those of us that can’t control every aspect of the light and exposure for all captures. While ISO 100 may indeed be the “optimal” for this or that sensor (best quality quality?), if shooting this way produces an unsharp image due to camera shake but shooting at ISO 400 doesn’t, with a bit more noise, seems clear what approach makes more sense. Sure, you have all the light you need to capture at the shutter/F-stop at ISO 100, why not. But I have plies of images I am happy with shot at ISO 1600 because that’s the only way I could get a capture in the first place. So yes, learn what the camera and raw converter is capable of producing.
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Yeah, unless you're using a tripod and so shutter speed isn't a factor don't worry about "optimum ISO," just worry about what's good enough at a given print size. That camera book offers that information under the assumption you have a cheaper (point and shoot) camera, with a smaller sensor, fewer pixels, and more noise.
You will be amazed how good the 5D is; up to at least 800ISO it will be clean enough that noise isn't an issue for prints up to 16X20 is my guess, especially with a little noise reduction in light room. I recently visited with a semi-famous professional who needs fast shutter speeds above all else for his variety of work, and he'll go up to 3200ISO if needed with the intention of some images then being wall-sized prints.
If you're doing architectural photography and want the absolute best results, look into a tilt/shift lens, which should be very familiar to you if you used to shoot and process large format. In which case you would want to use a tripod, in which case shutter speed is a non-issue and so you could use 100ISO under virtually any light. HDR and exposure masking are also really popular with digital architectural photography, so that's another reason to use a tripod and bracket exposures.
But I think you'll be very surprised how good the 5D is across a wide range of sensitivities, especially when considering the printed image or final web output (not the camera original blown up to 100%, where noise is more visible). That book was written with cheaper, less flexible cameras in mind. The same way every lens has one "best" f-stop but it's not the only one you'd use, every camera's "best" ISO is good to know but nothing to get so concerned about using all the time.
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That's correct. However, to expose to the right, you need to know that the camera histogram is based on the JPEG thumbnail that's embedded in the Raw fle. That JPEG will not show the real headroom of the Raw data because a tone curve was applied to the JPEG. You'll get a feeling for how it's different when you pay attention during Raw conversion. Just shoot some bracketed exposures and note the JPEG histogram and compare with the Raw histogram.
As far as dynamic range goes, in difficult situations you can also use bracketing and later do exposure fusion or HDR tonemapping. But for now, first concentrate on getting the exposure of a single frame right, the rest will follow from that.
Cheers,
Bart
Bart - I've recently read Michael's "Expose (to the) Right" tutorial and similar comments by Jeff Schewe in "Camera RAW in Adobe Photoshop CS5" and his "From Camera To Print - Fine Art Printing Tutorial" video tutorial with Michael. As you've said, I need to play/familiarize myself with my 5D MkII to know how the LCD histogram relates to the actual RAW histogram. A lot of this stuff is the exact opposite of my film experience - very interesting but backwards.
Thanks.
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Rather than finding absolute numbers, go out and get some shooting time with different iso settings under different lighting conditions. Get a feeling for what works best for you, rather than the numbers. Learn what your camera is capable of producing under different speeds and lighting and you'll be able to master this part of the craft.
You'll learn more than you can from running software generating a bunch of numbers and get more hands-on with your camera, thus get to know it better.
To get a reasonable approximation of what the chip sees, you've got to turn the camera's rendering intent to sRGB, turn down the contrast of the camera display a notch and run it at the normal color intent, not vivid, to get a closer version of what the chip sees. The image will appear flat.
The reason behind this is that your preview image is a rendered jpeg file created by the camera of the raw image. Those settings will skew the preview and thus give you even less accurate version of your final raw file. Since the file you are shooting is raw, color space is irrelevant.
Once in your raw workflow, you can then optimize your image, including setting the master file color space.
Nobody will ever see the numbers behind the image, it's the crafting of the final image for web, print, or otherwise that actually matters!
Larry:
Your comments are spot on - thanks. I can't wait to get some time with this camera. Long term I hope to find multiple "optimum" settings that work best in the shooting circumstances I may find myself in. I am simply looking for a good starting point to do some testing on my tripod and then work into other scenarios from there. While I can't control everthing, or sometimes very little, I want to end up with the best captures possible so that my post processing work is minimized - as much as possible.
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If you're doing architectural photography and want the absolute best results, look into a tilt/shift lens, which should be very familiar to you if you used to shoot and process large format. In which case you would want to use a tripod, in which case shutter speed is a non-issue and so you could use 100ISO under virtually any light. HDR and exposure masking are also really popular with digital architectural photography, so that's another reason to use a tripod and bracket exposures.
But I think you'll be very surprised how good the 5D is across a wide range of sensitivities, especially when considering the printed image or final web output (not the camera original blown up to 100%, where noise is more visible). That book was written with cheaper, less flexible cameras in mind. The same way every lens has one "best" f-stop but it's not the only one you'd use, every camera's "best" ISO is good to know but nothing to get so concerned about using all the time.
I've also got the Canon TS-E 24mm f/3.5L II Tilt-Shift coming with the 5D MkII. I'm very excited to use these tools.
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Hi,
My view may be that it is minimum ISO and expose to the right. That is probably optimum. On some cameras it may be possible to raise ISO quite a bit without loosing dynamic range (spelled as DR, pronounced like "shadow detail"). Shooting at 100 or 200 ISO may be safest bet. Always expose to the right, that is make sure that non specular highlights are close to clipping but still not clipped.
Look at the example based on DxO data. The Canon camera gives about the same DR up to ISO 640. The Sony has best DR at 119 ISO. So for Sony the best ISO would be around 120 and for Canon it may matter little, up to 640.
Best regards
Erik
Best regards
Erik Kaffehr
I'm new to the LL forum and returning to serious photography after a long hiatus. While I still have stains on my hands from working in my father's professional darkroom 30+ years ago, I am working hard at getting up to speed on the digital process. I got a copy of D-65's Lightroom Workbook today and have been reading with earnest. Seth/Jame make the statement that "Every digital camera has an optimum ISO setting"; and that "The best capture quality will be obtained using that [optimum] ISO". I've got a 5D MKII on order and would appreciate learning the best method to determine the optimum ISO for my camera. Sorry for the basic question; however, I want to get this right.
Thanks.
-
Hi,
My view may be that it is minimum ISO and expose to the right. That is probably optimum. On some cameras it may be possible to raise ISO quite a bit without loosing dynamic range (spelled as DR, pronounced like "shadow detail"). Shooting at 100 or 200 ISO may be safest bet. Always expose to the right, that is make sure that non specular highlights are close to clipping but still not clipped.
Look at the example based on DxO data. The Canon camera gives about the same DR up to ISO 640. The Sony has best DR at 119 ISO. So for Sony the best ISO would be around 120 and for Canon it may matter little, up to 640.
Best regards
Erik
Erik:
Thanks much for helping me translate the DxO graph. Your comments are helpful.
Take care.
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Hi Jeff. A couple of random thoughts.
Perhaps because the sensor elements are lined up in rows, instead of having sort of varying sized splodges in the emulsion, I find sharpness more an issue than iso with digital. I shoot at iso 100 unless the shutter speed is around say 1/20th to 1 second, when on my camera (5D2) on some surfaces, even with mirror lock up, just the shutter slamming open and shut can blur the image. Your tripod and the surfaces it stands on may give different results.
I start to really lose detail when stopping down to f16 and beyond due to diffraction.
Last night I started looking at the high iso abilities of the 5D2. After running the file though noise reduction there was not as much difference between the iso 100 and 6400 files in the mid to ¾ tones as I would have expected. Um, I'm going to have to reshoot the target to include complete blacks to better reflect a real world situation.
As the others here have said, there is no substitute for getting out in the real world and working out how to get the best from this camera. Have fun.
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i only use 160/320/640 etc on my MkII. and never use 100 you get pattern noise at 100 but not at 160. that's why those dxo charts are not the whole story as they never take into account the native iso.
(http://resourceroom.org/BANDING.jpg)
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i only skim read this thread before posting the above.
i disagree with a lot of what has been said, supposition and no user derived facts.
Fact 1. 160 is better then 100. no pattern noise in the blacks and the minimum of noise.
Fact 2. a good file is a good file and makes your job easier and you spend less time in front of the computer. if using 160 not 100 makes your life easier this is a good thing.
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I shoot at iso 100 unless the shutter speed is around say 1/20th to 1 second, when on my camera (5D2) on some surfaces, even with mirror lock up, just the shutter slamming open and shut can blur the image. Your tripod and the surfaces it stands on may give different results.
Did you experiment with livemode in these cases? I was under the impression that livemode actually was slightly superior to MLU in terms of shake in recent Canon DSLRs.
-h
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i only use 160/320/640 etc on my MkII. and never use 100 you get pattern noise at 100 but not at 160. that's why those dxo charts are not the whole story as they never take into account the native iso.
I am curious if there is such a graph for the 7D.
For most of my (admittedly brief) experience shooting DSLR I have tried to stick to ISO 100 religiously. (I shoot predominantly macro.)
Lately, I have had the opportunity to review multiple images from various nature photographers, many of which were truly stunning, and almost none of them were shot at ISO 100 ... but instead were shot @ ISOs 400 and 800.
I have found that, shooting at these higher ISOs has removed the need for flash in most of my images and also allows me to use a faster shutter speed. As such, I almost never shoot at ISO 100 any longer. It is interesting to me that (for the 5DII) the ISOs 160, 320, 640 are the preferred ISOs as well as being successive doubles of each other.
So I am curious to know if there was such a patten with the 7D.
Thanks for any input,
Jack
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Most digital cameras don't have an optimum ISO setting. Instead, they have two.
At one ISO setting—usually the very lowest, typically ISO 50/18°, ISO 80/20°, or ISO 100/21°, in some cameras called 'pull'—the digital noise is at its optimum. i. e. lowest. At some other ISO setting—usually one or two stops above the lowest, typically ISO 160/23° or ISO 200/24°, in some cameras the lowest that's not marked 'pull'—the dynamic range is at its optimum, i. e. widest. These two optima usually don't coincide. Exceptions to this rule may exist, in particular at very large or very small sensor formats.
I would like to see data and analysis supporting these two optima. The best DR and SNR will be obtained when the sensor is at saturation. From my experience with Nikon D3, whose base ISO is 200, an ISO of 100 is available, but this is merely overexposure. If you use the same exposure (f/stop and shutter speed), the raw files at the two ISOs are the same. The electronic amplification is the same for these ISOs. The DXO measured ISOs are the same for the camera set ISOs of 100 and 200, consistent with this observation. DXO shows the same situation for the Canon 5D Mark II. Unfortunately, DXO does not measure the DR and SNR for these overexposure modes.
Roger Clark's (http://www.clarkvision.com/articles/evaluation-1d2/) data for the Canon 1D do show that the lowest ISO, 50, does have higher signal-to-noise ratios than ISO 100, but at the expense of lower dynamic range and danger of saturating highlights. An ISO of about 75 would be a better match to the sensor range and would not sacrifice dynamic range. Unfortunately, ISO 75 is not available. I take this to mean that the sensor saturation would occur at an ISO of 75.
Regards,
Bill
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The best DR and SNR will be obtained when the sensor is at saturation.
If the sensor is at saturation then dynamic range is zero.
From my experience with Nikon D3, whose base ISO is 200/24°, an ISO of 100/21° is available, but this is merely overexposure.
Sure. That's why it reduces both noise and dynamic range. So for that camera, ISO 100/21° is the optimum for low noise; ISO 200/24° (most likely) is the optimum for dynamic range.
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Did you experiment with livemode in these cases? I was under the impression that livemode actually was slightly superior to MLU in terms of shake in recent Canon DSLRs.
-h
Yes, I believe so too. But the times I've used it I've found it sometimes inconvenient to implement (standing around in the freezing cold waiting for the right moment to fire the shutter).
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If the sensor is at saturation then dynamic range is zero.
Sure. That's why it reduces both noise and dynamic range. So for that camera, ISO 100/21° is the optimum for low noise; ISO 200/24° (most likely) is the optimum for dynamic range.
By at saturation, I mean that the highlights are at saturation or just below it, that is fully exposed to the right. This will produce maximum DR. You are incorrect on your second point. Overexposing will blow the highlights. The shadows will have a better SNR. What you gain at the low end, you lose at the high end.
Regards,
Bill
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I've also got the Canon TS-E 24mm f/3.5L II Tilt-Shift coming with the 5D MkII. I'm very excited to use these tools.
Jeff, with that camera and lens combination and your best shooting techniques, you're going to quickly be making some amazing images. My advice is to early on get into as many extremities of light and shadow as you can, and push the 5DII and TS-E 24II as far as you can, in every way you can think of. Shoot as much as your batteries can sustain and your cards can hold (wait until the sweet reality of "no film costs" filters down to gut level!). Then get those RAW files up on your monitor and see what is beautiful, what is fixable and what is discardable. By refining the beautiful and repairing the fixable, you'll soon gain confidence in the combination of the your gear's abilities and your skill at using today's software to produce quality work from less-than-optimum conditions.
- Daws
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Hi,
These are the DxO graphs for Canon 7D, 60D and Nikon D300s.
Two graphs, one showing DR vs. ISO and the other showing SNR (Signal Noise Ratio) vs. ISO.
Nikon uses a Sony chip, with massively parallel on chip AD-converters. The near linear DR vs. ISO is typical of that solution, it seems.
Best regards
Erik
I am curious if there is such a graph for the 7D.
For most of my (admittedly brief) experience shooting DSLR I have tried to stick to ISO 100 religiously. (I shoot predominantly macro.)
Lately, I have had the opportunity to review multiple images from various nature photographers, many of which were truly stunning, and almost none of them were shot at ISO 100 ... but instead were shot @ ISOs 400 and 800.
I have found that, shooting at these higher ISOs has removed the need for flash in most of my images and also allows me to use a faster shutter speed. As such, I almost never shoot at ISO 100 any longer. It is interesting to me that (for the 5DII) the ISOs 160, 320, 640 are the preferred ISOs as well as being successive doubles of each other.
So I am curious to know if there was such a patten with the 7D.
Thanks for any input,
Jack
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You are incorrect on your second point.
No, I'm not.
Overexposing will blow the highlights. The shadows will have a better SNR. What you gain at the low end, you lose at the high end.
That is exactly what I keep saying. The highlights will get blown only if there are any highlights to blow in the first place. If there aren't any then nothing will get blown. So in situations where you can get away with the reduced dynamic range at the highlight end, you may take advantage of the improved (i. e. reduced) shadow and mid-tone noise. That's why the ISO 100/21° setting exists. It does make sense, sometimes—even if some fail to understand it.
So—the optimum for noise is not the optimum for dynamic range, and the optimum for dynamic range is not the optimum for noise. So we have two optima ... or even three if we take other aspects into consideration (the third being the setting that is optimal for actually getting the image—after all, you don't always shot at ISO 100/21° or ISO 200/24°, do you?).
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Hi,
These are the DxO graphs for Canon 7D, 60D and Nikon D300s.
Two graphs, one showing DR vs. ISO and the other showing SNR (Signal Noise Ratio) vs. ISO.
Nikon uses a Sony chip, with massively parallel on chip AD-converters. The near linear DR vs. ISO is typical of that solution, it seems.
Best regards
Erik
Thanks for taking the time to post these graphs Erik. They're a little different from the previous graph.
Am I reading them right to conclude that the 7D has overall slightly-better DR at most ISOs, but overall slightly more noise also?
Jack
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No, I'm not.
That is exactly what I keep saying. The highlights will get blown only if there are any highlights to blow in the first place. If there aren't any then nothing will get blown. So in situations where you can get away with the reduced dynamic range at the highlight end, you may take advantage of the improved (i. e. reduced) shadow and mid-tone noise. That's why the ISO 100/21° setting exists. It does make sense, sometimes—even if some fail to understand it.
So—the optimum for noise is not the optimum for dynamic range, and the optimum for dynamic range is not the optimum for noise. So we have two optima ... or even three if we take other aspects into consideration (the third being the setting that is optimal for actually getting the image—after all, you don't always shot at ISO 100/21° or ISO 200/24°, do you?).
More experienced photographers practice ETTR (exposure to the right). If the highlights have headroom, one gives more exposure. You could use ISO 100 for this purpose, but one stop more exposure might not be the appropriate value to use. Leave the ISO setting at ISO 200 and employ ETTR.
Personally, I never shoot at ISO 100 (LO 1) with the D3. For a given exposure (f/stop and shutter speed) one gets the same results as shown in the graph below. What evidence do you have for your confused theories?
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Jeff, with that camera and lens combination and your best shooting techniques, you're going to quickly be making some amazing images. My advice is to early on get into as many extremities of light and shadow as you can, and push the 5DII and TS-E 24II as far as you can, in every way you can think of. Shoot as much as your batteries can sustain and your cards can hold (wait until the sweet reality of "no film costs" filters down to gut level!). Then get those RAW files up on your monitor and see what is beautiful, what is fixable and what is discardable. By refining the beautiful and repairing the fixable, you'll soon gain confidence in the combination of the your gear's abilities and your skill at using today's software to produce quality work from less-than-optimum conditions.
- Daws
Hey Daws;
Thanks for comments and encouragement. Getting familiar with this new equipment will be great fun and most instructive.
Take care.
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More experienced photographers practice ETTR (exposure to the right). If the highlights have headroom, one gives more exposure. You could use ISO 100/21° for this purpose ...
Exactly. So why are you argueing against me? Obviously you don't understand your own statements. It does absolutely not make any difference, technically, whether you set your light meter to ISO 200/24° and, ignoring the metering, over-expose deliberately by one stop on your own devices, or set your light meter to ISO 100/21° and let it control the exposure automatically. In both cases you're effectively using ISO 100/21°, in both cases you're sacrificing dynamic range, and in both cases you're getting less shadow noise. So what's your problem?
What evidence do you have for your confused theories?
To the confused, everything appears confused.
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Andrey (author of RPP) talks a lot about how ETTR isn't generally necessary in newer cameras, and exposing midtones more than a stop or so can affect color.
http://forum.getdpi.com/forum/showthread.php?t=7885 (http://forum.getdpi.com/forum/showthread.php?t=7885)
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exposing midtones more than a stop or so can affect color.
Increased flare (veiling or otherwise) from ETTR may change color, but aside from that I can't think of anything else that would affect color aside from a braindamaged raw converter (unfortunately many of them are/were).
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Exactly. So why are you argueing against me? Obviously you don't understand your own statements. It does absolutely not make any difference, technically, whether you set your light meter to ISO 200/24° and, ignoring the metering, over-expose deliberately by one stop on your own devices, or set your light meter to ISO 100/21° and let it control the exposure automatically. In both cases you're effectively using ISO 100/21°, in both cases you're sacrificing dynamic range, and in both cases you're getting less shadow noise. So what's your problem?
I do understand my own statements, but you apparently don't. One thing you are missing. When one increases the ISO of a camera such as the D3 over base two things are done: 1) the metering causes less exposure to be given and 2) the amplifier gain is increased so that the full scale of the ADC is used. For example, if you raise the ISO set on the camera to 400 from the base of 200, only half as much exposure is given and amplification is doubled so that the the raw data values are recorded at the same level as before.
If you set the camera to Lo1 (ISO 100), the metering changes but the amplification does not. There is no need to change the ISO. Merely expose to the right. There is only one optimum ISO for the D3, contrary to your assertions. I don't know how Canon handles this situation, but I suspect that it is the same as with the D3 (according to the DXO ISO data). Rather than confuse the op with your double talk about two optima, I would merely advise him to shoot at base ISO and expose to the right.
If a higher ISO is needed due to shutter speed or f/stop considerations, as pointed out by the DigitalDog earlier in this thread, one should be aware of the characteristics of the camera as explained by Emil Martinec (http://www.luminous-landscape.com/forum/index.php?topic=42158.msg352373#msg352373). Often, one can increase exposure in the raw converter and preserve highlight headroom. However, the histogram would not be to the right. It is the number of photons collected and not the appearance of the histogram that is important. That is one thing that Michael does not point out in his essay.
Regards,
Bill
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I don't know how Canon handles this situation.
Exact same, with few exceptions. The "Lo" ISO (ISO 50 on Canon) changes only metering and metadata. One of the exceptions was the original 5D, which implemented Lo ISO with irreversible gain in-camera -- they've since fixed that braindamage (only to make room for new and more innovative ways to design the camera wrong, like the angular response and 1/3 stop digital pushes).
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These are the DxO graphs for Canon 7D, 60D and Nikon D300s.
Two graphs, one showing DR vs. ISO and the other showing SNR (Signal Noise Ratio) vs. ISO.
Nikon uses a Sony chip, with massively parallel on chip AD-converters. The near linear DR vs. ISO is typical of that solution, it seems.
Erik. The DR graphs you post are instructive. The lower slope to the left of the DR curve for the Canon means that the camera is not using the full range of the sensor. This is usually to to the electronics and ADC. Read noise increases at low ISO. With ideal electronics, one would lose a stop of DR for each doubling of ISO as Emil Martinec (http://www.luminous-landscape.com/forum/index.php?topic=42158.msg352373#msg352373) explains here.
The SNR plots at 18% are in the range where photon shot noise is predominant and read noise is less important.
Regards,
Bill
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Yes, that was the idea...
And thank you for your very good explanation.
Best regards
Erik
Erik. The DR graphs you post are instructive.
....
Regards,
Bill