Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: OpticalMedia on December 07, 2009, 10:24:30 am
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I'm not too sure if this is an anomaly or if it is normal with my setup? 5d mark2 with 24-105 L lens. The out of focus highlights seem very badly transitioned and the one has a unattractive blue hue around. This may be expected as the sky is blue but surly the transition should be smoother? check at the sunset shot the highlight is blown as expected however is it normal to transition so unattractively? All images where shot and processed with everthing zeroed in adobe camera raw. The images are basically flatted unprocessed jpegs.
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I'm not too sure if this is an anomaly or if it is normal with my setup? 5d mark2 with 24-105 L lens. The out of focus highlights seem very badly transitioned and the one has a unattractive blue hue around. This may be expected as the sky is blue but surly the transition should be smoother? check at the sunset shot the highlight is blown as expected however is it normal to transition so unattractively? All images where shot and processed with everthing zeroed in adobe camera raw. The images are basically flatted unprocessed jpegs.
It's a clipping problem. Read this article (http://www.visual-vacations.com/Photography/exposure_metering_strategies.htm) for an explanation of the cause of the problem and what you can do to fix it.
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ISO 50
The 5D2, like all other Canon DSLRs, does not have any ISO 50. If you select 50, the metering occurs for 50 but the shot is made with 100. When converting, the raw processor, at least DPP and LR/ACR compensate for the extra exposure by applying -1 EV adjustment - but that does not gain back the blown details. Thus your shots were done with +1 EV exposure bias.
Never use ISO 50 when shooting raw, and very cautiously with JPEG. (If we are at it: and never use 1/3 stop ISOs with raw.)
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ISO 50
.... (If we are at it: and never use 1/3 stop ISOs with raw.)
Hi PP.
Pardon my ignorance, but I don't understand this proviso.
Roy
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I don't understand this proviso.
I assume the question relates to the 1/3 ISO steps.
Only the 1Dxxx models have analog gain for the 1/3 EV ISO steps; the others are using the next lower respectively the next higher ISO and numerically manipulate the resulting data. The effect is, that the full stop +1/3 steps are using too low exposure (for example metered for ISO 250 but shot with ISO 200), but the result gets numerically adjusted and the top 1/3 EV clipped. On the other hand, the full step - 1/3 EV ISO steps are "overmetered" by 1/3 EV. For example ISO 320 is metered for 320, but shot with 400.
For a detailed explanation see ISO Setting with Canon 7D (http://www.cryptobola.com/PhotoBola/Canon7D_ISO.htm). It is correct regarding the 5D2 as well, except for the chapter The speciality of ISO 100 and 125.
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ISO 50
The 5D2, like all other Canon DSLRs, does not have any ISO 50. If you select 50, the metering occurs for 50 but the shot is made with 100. When converting, the raw processor, at least DPP and LR/ACR compensate for the extra exposure by applying -1 EV adjustment - but that does not gain back the blown details. Thus your shots were done with +1 EV exposure bias.
Never use ISO 50 when shooting raw, and very cautiously with JPEG. (If we are at it: and never use 1/3 stop ISOs with raw.)
So you saying the reason the clipping looks so unattractive etc is because I used iso L (which is 50 on my 5d mark 2 correct?) Why would canon have put this option in if it does this? Are you saying that if I shot iso 100 - then this problem I am referring to would not have occurred? And finally to clarify things if I shot at iso 125 for example would that mean I would get the same result as iso 50 (the problem im currently experiencing?)
best
Mike
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So you saying the reason the clipping looks so unattractive etc is because I used iso L (which is 50 on my 5d mark 2 correct?)
The shots you have posted were horrendeously overexplosed. Shooting with ISO 100 reduces the exposure by one stop (if you use the camera's metering). I have no way to say, if the shot was overexposed only by one stop - it is possible, that even the one stop reduction will not be enough and you have to apply a negative bias.
Why would canon have put this option in if it does this?
For those, who believe that they need it, no matter how. For example those shooting water falls want to increase the shutter time, no matter at what cost. Now, you can increase it by a +1 EV exposure bias, or by manual exposure, but if you are recording JPEG, the result will be too bright. USing ISO 50 instructs the camera to adjust the data before generating the JPEG. The same is happening with the raw converters: they do apply a -1 EV "Exposure" (with LR/ACR) or "Brightness" (with DPP) correction, thereby making up for the extra high exposure - but that can not help with clipping in the raw data.
Are you saying that if I shot iso 100 - then this problem I am referring to would not have occurred?
It would have been one stop less; perhaps that would have been enough to prevent clipping, and most probably it would have been enough to prevent leaving, which occured, if I see it right.
And finally to clarify things if I shot at iso 125 for example would that mean I would get the same result as iso 50 (the problem im currently experiencing?)
No;
- ISO 125 would have dictated an exposure 4/3 EV lower than what it was required with ISO 50,
- the shot would have been made with ISO 100,
- the resulting data would have been increased before recording the raw data, possibly causing a clipping by 1/3 EV.
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So you saying the reason the clipping looks so unattractive etc is because I used iso L (which is 50 on my 5d mark 2 correct?) Why would canon have put this option in if it does this? Are you saying that if I shot iso 100 - then this problem I am referring to would not have occurred? And finally to clarify things if I shot at iso 125 for example would that mean I would get the same result as iso 50 (the problem im currently experiencing?)
Any clipped image can display unattractive colour transitions in the partially saturated highlights, this is a disadvantage of digital, but if you set ISO50 these artifacts will be even more visible. The reason is that by setting ISO50 the camera works internally at ISO100 (therefore blowing more information than a real ISO50 would have), but afterwards a tone curve with a -1EV reduction is applied, and this -1EV compensation magnifies the artifacts found in the clipped highlights.
Your image would have looked better in the highlights by shooting at ISO100, and half exposure time. The price would have been some extra noise in the shadows.
Regards
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Any clipped image can display unattractive colour transitions in the partially saturated highlights, this is a disadvantage of digital, but if you set ISO50 these artifacts will be even more visible. The reason is that by setting ISO50 the camera works internally at ISO100 (therefore blowing more information than a real ISO50 would have), but afterwards a tone curve with a -1EV reduction is applied, and this -1EV compensation magnifies the artifacts found in the clipped highlights.
Your image would have looked better in the highlights by shooting at ISO100, and half exposure time. The price would have been some extra noise in the shadows.
Regards
Ran some of my own tests. Mirror lockup and manually focused so that highlight was out of focus. It is clear now that at ISO 50(or L) the out of focus highlight transitions look terrible! ISO 100 much better ! I have no idea who would use ISO 50??!! The third Image is ISO 125 the fourth ISO 160 and the 5th ISO 200. Images are all 100% grabs. No real world difference between the rest of the images after ISO 50...So i am still not 100%sure what panopeeper was on about with the rest of the ISO expansion options in between? Shed some light please, thanks a lot!
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No real world difference between the rest of the images after ISO 50...So i am still not 100%sure what panopeeper was on about with the rest of the ISO expansion options in between?
The difference between these is is not much, because the difference in the exposure is only 1/3 EV between the neighboring shots, and the camera adjusted the raw data to look like it would have been shot with the corresponding ISO gain (although this is not possible in all cases). Furthermore, the raw processors too apply their special twists. For example ACR applies +0.4 EV Exposure adjustment (clandestine, not visible on the slider) to all 5D2 shots with full-stop ISO (except ISO 50, which is adjusted by -0.6 EV); however, the full top -1/3 EV ISO shots are adjusted only by +0.08 EV. Thus the result of the conversion is pretty far from the raw data.
There is no disadvantage when using the -1/3 EV ISO steps, except that the metering is 1/3 EV too high, that can cause clipping. The +1/3 EV steps are undermetered and adjusted afterwards; that adjustment may cause clipping.
Anyway, these shots are not useful to demonstrate the differences; a well-defined scenery with clearly recognizable clipping can show the issues better, like in the 7D demo I linked to above. The raw files of these shots might be more useful to show, what happened.
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Gabor ("panopeeper") is right.
The simplest way to think of it, for Canon owners anyway, is this: The only "real" ISO settings are 100, 200, 400, etc. Any lower or in-between settings are fake (they acrtually use the nearest "real" ISO number), and may cause problems. I just never use them, and it doesn't cramp my photography in any meaningful way.
Eric
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Gabor ("panopeeper") is right.
The simplest way to think of it, for Canon owners anyway, is this: The only "real" ISO settings are 100, 200, 400, etc. Any lower or in-between settings are fake (they acrtually use the nearest "real" ISO number), and may cause problems. I just never use them, and it doesn't cramp my photography in any meaningful way.
Eric
This is very unsettling news. I was aware that ISO 50 is fake, and therefore never use it, but I had assumed that the 1/3 stop ISO values were real, and consequently used them quite often. I'll avoid doing so from now on.
I think it's unethical to add fake features like this, which do nothing more than cause potential problems. If I want to deliberately over or under expose my shot and then adjust it digitally I can do that myself thank you very much - I don't want the camera doing it behind my back. If Canon insist on adding such features, they should at least put a prominent warning in the manual, so that people will know not to use them.
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I think it's unethical to add fake features like this, which do nothing more than cause potential problems. If I want to deliberately over or under expose my shot and then adjust it digitally I can do that myself thank you very much - I don't want the camera doing it behind my back. If Canon insist on adding such features, they should at least put a prominent warning in the manual, so that people will know not to use them.
You are making the mistake here of thinking as a RAW shooter, when unfortunately cameras today are still JPEG oriented (see some of my complaints about this here (http://luminous-landscape.com/forum/index.php?showtopic=33267)).
When shooting JPEG fake ISOs are useful because you can't (or you shouldn't) post process your images, and therefore a finished image has to come out right from the camera. Think of the following 2 situations where fake ISOs can be useful to a JPEG shooter:
- You want to do a silk effect in the water of a river. The sunlight is so bright that at ISO100 and even with the lens stopped to f/22, the exposure time needed for your silk effect means you are globally overexposing your image. But by setting ISO50 and the same aperture and shutter, you get a proper global exposure. You won't recover any clipped highlights (since the RAW data are the same as shooting at ISO100 with the same aperture and shutter), but thanks to the camera ISO50 post processing you will get proper exposure for most of your JPEG that resulted overexposed shooting at ISO100.
- You are street shooting at night, in very low light conditions. Even at max aperture (f/2.8) and the longer exposure time your hands can afford, you get very dark JPEG images at the max real ISO (ISO1600/ISO3200 on most cameras, including the 5D2 BTW). Fake high ISO values such as ISO6400 or ISO12800 can provide you a properly exposed image. Of course they will be noisy, but it's better a noisy JPEG than no JPEG at all.
Of course the same philosophy that is valid for JPEG shooters, can be applied to RAW shooters who do not know/do not care about the inner workings of their cameras and RAW developers, and feel happy shooting at any ISO value provided by their camera.
Regards.
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Quite frankly I don't think anyone who cares enough about photography to spend thousands of dollars on a camara should be shooting JPEG, but that's another story.
I have nothing against Canon implementing fake features for the benefit of JPEG shooters, but they really ought to either disable such features in raw mode, or add a warning that you should only use them if you don't much care about quality.
I've done a little bit of internet research, and it seems that there's a lot of disagreement about whether the 1/3 stop ISO values on the 5D and 5D II are fake or not. Some people also think that ISO 6400 on the 5D II is fake, although it's a moot point for me - I never shoot above ISO 3200 due to excessive noise. I have no idea which information is reliable, so to be safe I'll avoid the 1/3 stop ISO values until such time as I find reliable information.
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Quite frankly I don't think anyone who cares enough about photography to spend thousands of dollars on a camara should be shooting JPEG, but that's another story.
I have nothing against Canon implementing fake features for the benefit of JPEG shooters, but they really ought to either disable such features in raw mode, or add a warning that you should only use them if you don't much care about quality.
I've done a little bit of internet research, and it seems that there's a lot of disagreement about whether the 1/3 stop ISO values on the 5D and 5D II are fake or not. Some people also think that ISO 6400 on the 5D II is fake, although it's a moot point for me - I never shoot above ISO 3200 due to excessive noise. I have no idea which information is reliable, so to be safe I'll avoid the 1/3 stop ISO values until such time as I find reliable information.
If you want to know what information is reliable, produce your own information. There is no mistery in extracting the RAW data and analysing it.
ISO6400 on the 5D2 is fake. It is not a matter of thinking it or not, just a matter of analysing the RAW files and seeing it; just look at these RAW histograms (http://www.guillermoluijk.com/article/isos5dmkii/histos.gif). Regarding the 1/3 stop ISOs, just read Gabor's (Panopeeper) findings.
Do you use your camera's histogram? that histogram is related to the embedded JPEG file, so it can be considered a fake histogram if you are shooting RAW (it displays information that has been clipped, mainly because of white balance, so it is not reliable to check how good your RAW data are. Just take a look: Camera's histogram reliable to the RAW data, Specific WB for realistic camera JPEG (http://luminous-landscape.com/forum/index.php?showtopic=22250)). People taking care about fake ISOs should also be concerned about a histogram that is lying to them, and seeing a bit farer, about how camera manufacturers are still making JPEG-oriented cameras, no matter how much they cost.
Regards
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Do you use your camera's histogram? that histogram is related to the embedded JPEG file, so it can be considered a fake histogram if you are shooting RAW (it displays information that has been clipped, mainly because of white balance, so it is not reliable to check how good your RAW data are. Just take a look: Camera's histogram reliable to the RAW data, Specific WB for realistic camera JPEG (http://luminous-landscape.com/forum/index.php?showtopic=22250)). People taking care about fake ISOs should also be concerned about a histogram that is lying to them, and seeing a bit farer, about how camera manufacturers are still making JPEG-oriented cameras, no matter how much they cost.
Regards
Yes, I was aware of that, and it annoys me greatly. I've commented on it a few times on other threads. For that reason I tend to bracket my landscape shots 1/3 of a stop either way, and examine them in ACR before deciding which one to keep. A proper raw histogram would be extremely useful, and would be easier to implement than the JPEG-oriented crap we have now. Having said that, lying about the histogram doesn't make it OK to lie about the ISO too. I don't think we really disagree about anything here.
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If you want to know what information is reliable, produce your own information. There is no mistery in extracting the RAW data and analysing it.
I think I'll do that when I have time. It didn't occur to me to do so until now, because I always assumed that all the ISO values other than the "expanded" ones were real. Now I have evidence to the contrary.
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And what about other brands like Nikon, Olympus, Sony ?!
Are 1/3 ISO steps fake ISO too ?
This is a very interresting thread and I think that it could turn into a more complete Tutorial or informative article because a lot of people ignore that !
Yes most of us know that extreme ISO are fake, but not 1/3 ISO steps.
Have a Nice Day !
Thierry
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Yes most of us know that extreme ISO are fake, but not 1/3 ISO steps.
Well, generally speaking, all ISO are fake in a digital camera. It's just a convenience, normalization. This is why 100 ISO doesn't really mean exactly the same thing in a camera or another. At the root, we have a photon counter: it doesn't really matter much if we multiply/divide at the AD converter, in the camera, or in software post-processing as long as the signal sits nicely between the points where noise becomes an issue and the point where horrible things such as dramatically non linear response, blooming, clipping occurs...
But of course, in practice, it helps a lot to have a camera normalized to the conventions we are familiar with and one that doesn't output a trash signal by default...
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And what about other brands like Nikon, Olympus, Sony ?!
Are 1/3 ISO steps fake ISO too ?
The 1Dxxx models do have analog ISO gain for the 1/3 steps as well.
Nikons, at least the D300 and above have analog gain for the 1/3 steps; I don't have such raw files from the lower and older models.
The Sony A700 seems to have analog gain, but I am not sure about that, because the raw data is much less raw than Canon's.
I don't have such raw files from most other cameras; I looked at the Olympus E3, that seems to be analog.
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At the root, we have a photon counter: it doesn't really matter much if we multiply/divide at the AD converter, in the camera, or in software post-processing
It does matter if you multiply in the analogue domain (electronic amplification) vs in the RAW domain (once data has been converted to digital).
Analogue amplification (genuine ISO) improves signal to noise ratio; software amplification (fake ISO) doesn't.
2 shots taken at T=1/4s, f/13, 50mm (note that the same aperture and shutter speed mean the same amount of photons entering the camera), just ISO was changed between them and exposure adjusted in pp to match on both images:
(http://www.guillermoluijk.com/article/iso/versus.jpg)
The higher the genuine ISO for a given amount of light hitting the sensor, the higher the SNR.
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It does matter if you multiply in the analogue domain (electronic amplification) vs in the RAW domain (once data has been converted to digital).
Analogue amplification (genuine ISO) improves signal to noise ratio; software amplification (fake ISO) doesn't.
2 shots taken at T=1/4s, f/13, 50mm (note that the same aperture and shutter speed mean the same amount of photons entering the camera), just ISO was changed between them and exposure adjusted in pp to match on both images:
The higher the genuine ISO for a given amount of light hitting the sensor, the higher the SNR.
I hear you but I was talking about electron counts as real raw data. Obviously, at 100 ISO, in this case, your electron count is too low so you aren't in the optimal zone I was talking about.
Signal to noise ratio is very simply the ratio of the signal you are measuring vs all the possible sources of noise
http://learn.hamamatsu.com/articles/ccdsnr.html (http://learn.hamamatsu.com/articles/ccdsnr.html)
All other things being equal, and with sufficient well capacity, if you defined "genuine iso" as the QE of the sensor, yes, SNR increases.
EDIT: if you aren't convinced by what I am saying, check the DXO labs analysis for different cameras and you will clearly see that there is one "sweet" spot for dynamic range and SNR (usually in the low "ISO" range) and that things go downhill for virtually all cameras from there as "ISO" increases. Analogue amplification doesn't improve things, far from it.
http://www.dxomark.com/index.php/eng/Image...abase/Nikon/D3X (http://www.dxomark.com/index.php/eng/Image-Quality-Database/Nikon/D3X)
around 80 ISO
http://www.dxomark.com/index.php/eng/Image.../EOS-5D-Mark-II (http://www.dxomark.com/index.php/eng/Image-Quality-Database/Canon/EOS-5D-Mark-II)
around 75 ISO
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Obviously, at 100 ISO, in this case, your electron count is too low so you aren't in the optimal zone I was talking about
Low counts. i.e. deep shadows are normal parts of an image.
All other things being equal, and with sufficient well capacity, if you defined "genuine iso" as the QE of the sensor, yes, SNR increases
Guillermo's genuine ISO is one, which is achieved by analog gain, not by numerical manipulation in the digital realm - this is clearly expressed in hos post.
check the DXO labs analysis for different cameras and you will clearly see that there is one "sweet" spot for dynamic range and SNR (usually in the low "ISO" range) and that things go downhill for virtually all cameras from there as "ISO" increases. Analogue amplification doesn't improve things, far from it
This is a misinterpretation of the analysis. Analog amplification does improve "things", it clearly increases the SNR (up to some camera dependent limit, for the high analog ISO steps not always improve the SNR).
The practical problem is, that increasing the ISO by 1 EV roughly doubles the pixel values. Going from ISO 100 to 1600 would require four bits more; that is probably too much for the A/D electronics (caution, I am incompetent on the HW domain). Thus, if the bit depth is for example 14, increasing the ISO from 100 to 200 would create 15 bit values; the top of that gets thrown away. The higher ISO enhanced the SNR, but it eliminated one stop from the highlights; therefor the dynamic range is reduced by the difference between one stop and the enhancement.
Look at the noise/DR graphs of the Canon 5D2; the difference between ISO 100 and 200 is very small, but from 1600 to 3200 the loss is practically a full stop (some copies of the 5D2 are somewhat better, they show a slight enhancement from 1600 to 3200 as well).
Canon 5D2 Noise/DR (http://www.panopeeper.com/Noise/Canon5DMkII_Noise.GIF)
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Keith from Northlight Images did an iso test with the 7D and it shows how using the in-between iso settings can result in higher noise than the full stop iso settings. 7D iso test (http://www.northlight-images.co.uk/article_pages/cameras/canon_7d_noise.html)
Derryck.
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Keith from Northlight Images did an iso test with the 7D and it shows how using the in-between iso settings can result in higher noise than the full stop iso settings
Keith posted this link on another thread; I looked at the method and found it meaningless.
There is an important point to understand when discussing this subject: the noise with different ISOs must be compared on patches with equal light capture. Most photogs don't understand this.; they compare two shots with different ISO and with vastly different light capture. When increasing the ISO by one stop, the metered exposure decreases by one stop. The ISO increase increases the SNR, but the reduced light capture decreases it more; thus the higher ISO seems to yield higher noise, and the users attribute that to the higher ISO.
The meaning of this regarding the 1/3 ISO stops is, that even though the ISO gain is the same for example for ISO 200 and 250; or for ISO 320 and 400, the exposure is different. For example make a shot with ISO 400, metered exposure. Then make a shot with ISO 320, metered exposure. The ISO used in the 320 shot is ISO 400, but the exposure is higher, thus the noise is less - most users interpret this as ISO 320 is "better than ISO 400". On the other hand, ISO 250 is in fact ISO 200, but the exposure is 1/3 EV lower, i.e. it shows higher noise - again, due to the exposure, not to the ISO.
The study The Source of Noise (http://www.cryptobola.com/PhotoBola/SourceOfNoise.htm) contains detailed exlanations and demonstrations of these issues.
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This is a fascinating conversation. I have learned lots.
This issue has made me more careful about the old digital mantra ETTR (expose to the right), particularly when people say it is okay to see a bit of clipping in highlights because you should be able to recover it with RAW. What you can easily overlook is how much your RAW processing can recover and, more importantly, whether one particular color channel is clipping substantially more than others. Clipping in the blue channel, for example, can ruin your ability to recreate a good smooth sky, though the rest of the image looks fine.
I was out in the snow last weekend and these issues were on my mind. I have started to actually pull back from aggressive ETTR because the other consequence is that you end up blowing out skies and clouds in the effort to make the snow white. I'll take a good bell curve histogram any day, and I will try to shift it to the right, but not so much that the line approaching zero is off the edge. Further, you can easily miss the fact that there is a spike just outside the right border of the JPG preview histogram.
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This issue has made me more careful about the old digital mantra ETTR (expose to the right), particularly when people say it is okay to see a bit of clipping in highlights because you should be able to recover it with RAW. What you can easily overlook is how much your RAW processing can recover and, more importantly, whether one particular color channel is clipping substantially more than others
The problem with looking at the clipping indication on the camera is, that you don't know if the clipping occured on raw level, leading to incorrect pixel values, or it is the creature of the raw conversion, caused by WB application, color space conversion and adjustments. Only a neutral setup in the camera helps by contributing to more or less raw-like histograms and clipping indication.
The so-called recovery function of ACR, controlled by the slider, does not recover anything, which was really lost. ACR - and other raw converters - often indicate clipping, when the raw data was in fact very far from clipping, but the resulting color falls outside of sRGB. Reducing the intensity by "exposure" or "recovery" brings the color into the sRGB gamut.
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Yes, by recover blown highlights, I wasn't really referring to the recovery slider. I generally don't find it helpful. Exposure coupled with Brightness seems to have better results. Better than those is to do two different raw outputs and then blend them with auto align layers and masking techniques. I even like this better than, so called, pseudo HDR using single RAW frames processed with different exposures.
One technique I have been enjoying some success with is to decrease the luminance and increase the saturation of only the blue channel in ACR. Generally for landscape, you don't see this create unpleasant blue casts elsewhere in the image because there aren't many natural things that are made with the color blue, except for perhaps sky, water and ice. In those cases, you probably are okay with tweaking the blue levels. The only possible problem with this, and it is related to the original poster, is when you can create some posterization by pushing the blue channel too far out of synch with the other color channels.
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Analogue amplification doesn't improve things, far from it.
So lucky me for having a Canon 350D with such magical features.
Regards.
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Keith posted this link on another thread; I looked at the method and found it meaningless.
Thanks mate :-) - meaningless for you in respect of your different criteria I'd say...
I still stand by the results in the context they were given - they show variations in noise, as would be found in real world files processed the way most people process them.
I make no claims as to how various hardware and software does things between light going into the lens and ACR producing an image for me. Sometimes this is relevant, other times the process might as well be carried out by smart imps inside the camera and my computer.
Just depends why you are looking at things.
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If you want to know what information is reliable, produce your own information. There is no mistery in extracting the RAW data and analysing it.
I'm not completely clear how to do this ... take two identical images at the two ISO's and then examine the RAW histogram? I assume doing this in most raw processors wouldn't work since they are applying a correction based on the ISO (thus faking it). Is this the right steps and which program would you use?
Is ISO 50 on the PhaseOne p65+ real? I've assumed it was since they recommend using it when you can.
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I'm not completely clear how to do this ... take two identical images at the two ISO's and then examine the RAW histogram?
Exactly - but you have to look at the raw channel histograms.
Example: the 5D2, a set of shots with different ISOs from Imaging Recources; controlled illumination, exposure steps corresponding to the ISO steps. The histograms from ISO 400, 200 and 100 are practically identical, for doubling the exposure and halving the ISO are "compensating" for each other. But watch the ISO 50 shot: the histogram shows the 1 EV higher exposure, because the ISO gain is the same as with ISO 100.
ISO 400 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 200 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 100 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 50 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
Is ISO 50 on the PhaseOne p65+ real? I've assumed it was since they recommend using it when you can
I don't have raw files from the P65+, but I am pretty sure ISO 50 to ISO 800 are real, like with the P45+. However, "real" is not always "effective"; the highest real ISO gains of several cameras do not reduce the noise the least, they reduce the dynamic range by one full stop.
On the other hand, several other MFDBs, for example the P25+ don't have higher ISO than 100 (I guess they have real ISO 50 as well). ISO 200 and above are identical to ISO 100 (unlike the faked ISO gain of Canons and Nikons), "making true" the ISO is the task of the raw processing.
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Exactly - but you have to look at the raw channel histograms.
Example: the 5D2, a set of shots with different ISOs from Imaging Recources; controlled illumination, exposure steps corresponding to the ISO steps. The histograms from ISO 400, 200 and 100 are practically identical, for doubling the exposure and halving the ISO are "compensating" for each other. But watch the ISO 50 shot: the histogram shows the 1 EV higher exposure, because the ISO gain is the same as with ISO 100.
ISO 400 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 200 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 100 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
ISO 50 (http://www.panopeeper.com/Canon/Canon5DMkII_ISO00400_Hist.GIF)
I don't have raw files from the P65+, but I am pretty sure ISO 50 to ISO 800 are real, like with the P45+. However, "real" is not always "effective"; the highest real ISO gains of several cameras do not reduce the noise the least, they reduce the dynamic range by one full stop.
On the other hand, several other MFDBs, for example the P25+ don't have higher ISO than 100 (I guess they have real ISO 50 as well). ISO 200 and above are identical to ISO 100 (unlike the faked ISO gain of Canons and Nikons), "making true" the ISO is the task of the raw processing.
Thanks. Unfortunately your links aren't working. this is quickly getting a little over my pay grade
So which program is the best to allow me to see raw channel histograms?
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…So which program is the best to allow me to see raw channel histograms?
Rawnalyze should do the trick ( http://www.cryptobola.com/PhotoBola/Rawnalyze.htm (http://www.cryptobola.com/PhotoBola/Rawnalyze.htm) ).
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Rawnalyze should do the trick ( http://www.cryptobola.com/PhotoBola/Rawnalyze.htm (http://www.cryptobola.com/PhotoBola/Rawnalyze.htm) ).
Doesn't appear to support files from PhaseOne backs.
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Doesn't appear to support files from PhaseOne backs.
Convert the raw file in mosaic DNG format (for example with the Adobe DNG converter), then it should work. Linear DNGs, which are demosaiced, are not supported by Rawnalyze (those are not raw any more).
Unfortunately your links aren't working
The site is blocked as the moment. Someone or something reported some "malicious content" without specifying, which file, and the service provider blocked everything. I am in the "process of resolution".