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Author Topic: SPECTACULAR: 5D MKII's DR in DPreview  (Read 16346 times)
Guillermo Luijk
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« on: February 14, 2009, 11:00:43 PM »
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According to DPreview, the Canon 5D MKII can capture the same DR from ISO100 to ISO1600. But that is not all folks, it can even capture more DR at ISO3200!

         
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Panopeeper
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« Reply #1 on: February 14, 2009, 11:32:10 PM »
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This is not the first camera; the Nikon D300 is said to have higher DR at ISO 400 than at ISO 200.

But that's not all.

1. the lowest ISO is said to have lower DR than the next one,

2. the fake ISOs are said to have some gain (in fact the DR is always a full stop lower with the fake ISO steps).

The Nikon D3 is an even more miraculous camera: from ISO 100 to 200 it gains 1.1 EV, it goes lower at ISO 400, then again higher at 800 and even higher at 1600, and it drops only 0.5 EV from 12800 to 25600.

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Gabor
Guillermo Luijk
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« Reply #2 on: February 14, 2009, 11:49:05 PM »
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BTW Gabor I wanted to check by myself the fake ISO6400 on this camera (which is contrary to what the camera user manual suggests), and found a combed histogram which makes me think of fake ISO as you said:



But the holes, strangely, are not 100% empty, there are pixels on them. In a negligible amount though.
How would you explain that? perhaps some rounding errors in building the ISO6400 RAW file from the ISO3200 capture?

BR
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Panopeeper
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« Reply #3 on: February 15, 2009, 12:08:16 AM »
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Quote from: GLuijk
BTW Gabor I wanted to check by myself the fake ISO6400 on this camera (which is contrary to what the camera user manual suggests), and found a combed histogram which makes me think of fake ISO as you said:
Neither Canon, nor Nikon afford to declare the truth. Two fake ISOs at the top must be the maximum; basta. The vast majority of users don't have any idea of this issue anyway, and believe everything written in the papers.

I was confronted for a short while ago with a Nikon paper stating, that the D2H applies an analog gain depending on the white balance. Some Nikonists took it as hard cash. I have proven that this is not so, then the question was "why would someone from Nikon lie?"

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But the holes, strangely, are not 100% empty, there are pixels on them. In a negligible amount though
That is sometimes a single pixel; sometimes a few. I have no idea how this happens.
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Gabor
Ray
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« Reply #4 on: February 15, 2009, 06:44:10 AM »
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Quote from: GLuijk
According to DPreview, the Canon 5D MKII can capture the same DR from ISO100 to ISO1600. But that is not all folks, it can even capture more DR at ISO3200!

Guillermo,
The figures to which you refer relate to default camera jpegs. Another way of looking at this would be to say that the default jpeg DR of the 5D2 is only 1 & 2/3rds stops down at ISO 3200, but almost 2 stops down at ISO 100 to ISO 1600. It might be the case that Canon have done a really good job of maintaining DR at ISO 3200, and that there is no further DR increase to be gained by shooting RAW at ISO 3200. Whereas, using ACR with 5D2 RAW images at ISO 100, allows for nearly 2 stops of additional DR to be extracted.
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Guillermo Luijk
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« Reply #5 on: February 15, 2009, 06:57:24 AM »
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Quote from: Ray
The figures to which you refer relate to default camera jpegs. Another way of looking at this would be to say that the default jpeg DR of the 5D2 is only 1 & 2/3rds stops down at ISO 3200, but almost 2 stops down at ISO 100 to ISO 1600. It might be the case that Canon have done a really good job of maintaining DR at ISO 3200, and that there is no further DR increase to be gained by shooting RAW at ISO 3200. Whereas, using ACR with 5D2 RAW images at ISO 100, allows for nearly 2 stops of additional DR to be extracted.
Ray IMO it's much simpler than that, and the reason has nothing to do with the camera's JPEGs: DPreview's DR figures are just crap since their measurement criteria is completely wrong from any scientifical point of view. I just opened the thread to make some fun and, perhaps, hope someone in the team reaches it and, perhaps, has the splendid idea to suggest a change in their methods.

If they were right, the conclusion would be that every JPEG photographer with a Canon 5D MKII should stick with Loctite their ISO adjustment to 3200, since it is clearly the optimum ISO value according to that table.

BR
« Last Edit: February 15, 2009, 07:02:51 AM by GLuijk » Logged

Ray
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« Reply #6 on: February 15, 2009, 07:19:10 AM »
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Quote from: GLuijk
If they were right, the conclusion would be that every JPEG photographer with a Canon 5D MKII should stick with Loctite their ISO adjustment to 3200, since it is clearly the optimum ISO value according to that table.

You might be right, but there is also the issue of noise. I get the impression from the DXOMark website that there is sometimes a significant difference between a camera's DR performance at a particular ISO and the SNR at the same ISO. In other words, camera A might have better DR than camera B, but worse SNR than camera B at the same ISO.

I'm suggesting that the 5D2 jpeg at ISO 3200 might have approximately the same DR as the default jpeg at ISO 100, but much more noise than the jpeg shot at ISO 100. You would therefore not wish to glue your ISO adjustment to ISO 3200. Dynamic Range is not everything.
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Guillermo Luijk
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« Reply #7 on: February 15, 2009, 07:41:28 AM »
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It is strange, but it is correct that a camera A noisier in most of the range, can have higher DR than a less noisy in most of the range camera B, as long as camera A gets less noisy than camera B in the deep shadows, where the SNR threshold is set for the DR criteria chosen.

But we are talking of the same camera here, and the 5D MKII will by certain be noisier in the _whole_ range at ISO3200 than at ISO100 for any given RAW exposure. So, if we assume DR is deeply related to noise (in fact it's just the range in which SNR does not fall below a chosen SNR threshold), I cannot believe by any means that the in-camera JPEG generation is so badly designed that produces valid information along a larger range at ISO3200 than at ISO100. And of course, the ISO100 image will be less noisy than the ISO3200 in the _whole_ range if RAW exposure is kept on both ISO settings, as is expected (i.e. shutter/aperture vary accordingly to the ISO set).
« Last Edit: February 15, 2009, 02:28:20 PM by GLuijk » Logged

Ray
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« Reply #8 on: February 15, 2009, 09:14:10 AM »
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Quote from: GLuijk
I cannot believe by any means that in-camera JPEG generation is so crappy that produces valid information along a larger range at ISO3200 than at ISO100. And of course, the ISO100 image will be less noisy than the ISO3200 in the _whole_ range if RAW exposure is kept on both ISO settings as expected (i.e. shutter/aperture vary accordingly to the ISO set).

Whatever the DR of the 5D2 at ISO 3200, the noise appears to be so bad (according to dpreview) that its resolution advantage compared with the D700 is wiped out. DXOmark doesn't address resolution, but at ISO 1600 and higher, both noise and dynamic range for the 5D2 and D700 are the same at a normalised 8x12" size. It would seem that at ISO 3200 and above, the D700 has slightly greater resolution than the 5D2 at any print size, acording to dpreview.
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JohnBrew
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« Reply #9 on: February 15, 2009, 11:17:06 AM »
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Quote from: Ray
Whatever the DR of the 5D2 at ISO 3200, the noise appears to be so bad (according to dpreview) that its resolution advantage compared with the D700 is wiped out. DXOmark doesn't address resolution, but at ISO 1600 and higher, both noise and dynamic range for the 5D2 and D700 are the same at a normalised 8x12" size. It would seem that at ISO 3200 and above, the D700 has slightly greater resolution than the 5D2 at any print size, acording to dpreview.

Not sure what all the commotion is about. The Sony A900 blows all of them out of the water for DR (albeit at low ISO).
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Ray
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« Reply #10 on: February 15, 2009, 07:53:29 PM »
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Quote from: JohnBrew
Not sure what all the commotion is about. The Sony A900 blows all of them out of the water for DR (albeit at low ISO).

Not quite. It's the Nikon D3X that blows all of them out of the water, as Bernard Languillier will be pleased to inform you   .
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Ray
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« Reply #11 on: February 15, 2009, 08:14:29 PM »
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Quote from: GLuijk
But we are talking of the same camera here, and the 5D MKII will by certain be noisier in the _whole_ range at ISO3200 than at ISO100 for any given RAW exposure.

Guillermo,
It's interesting that DXOmark show approximately a 2 stop difference in DR between ISO 3200 and ISO 100. Dpreview claim slightly less than a 2 stop DR difference between the default jpeg at ISO 3200 and the auto-adjusted RAW ISO 100 image in ACR. Their methodology is different, but the results in some respects seem very close.

We know that in-camera processing can be very good, but it might not be the type of processing we prefer for any particular image.

It's conceibable to me, that Canon have made a decision with regard to in-camera processing of ISO 3200 images, to preserve the maximum dynamic range that the signal allows. At lower ISOs, Canon are probably applying different tone curves, and other adjustments, to make the image look as pleasing as possible, but at the sacrifice of some degree of DR.

Does that make sense?


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BernardLanguillier
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« Reply #12 on: February 15, 2009, 09:01:26 PM »
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Quote from: Ray
Not quite. It's the Nikon D3X that blows all of them out of the water, as Bernard Languillier will be pleased to inform you   .

Indeed. Well controlled highlights, noiseless shadows and a pleasant contrasty curve, without mentioning the fact that this was shot with a T/S lense.



This doesn't take away anything from the A900's abilities though.

Cheers,
Bernard
« Last Edit: February 15, 2009, 09:07:31 PM by BernardLanguillier » Logged

A few images online here!
alba63
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« Reply #13 on: February 16, 2009, 10:45:23 AM »
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Indeed, the dpreview DR measurings, but also the other sites' numbers for DR are quite confusing, they differ substantially (with DXO mark having the highest numbers) and in the end they don't tell much.

I have found Lloyd Chambers' blog ("DAP" on diglloyd.com) to give the most valuable information concerning IQ of the latest DSLRs. Lloyd is quite critical towards the 5dII, specially in terms of shadow noise (which tends to produce banding patterns) and colour. He shows picture samples to make his point, colour has been a critical point with Canon indeed, I have never really appreciated the slightly muted (or alternatively artificially boosted look of my 5d Mark I). Using high quality lenses la Zeiss ZF betters it's output, but still doesn't make it as vivid and photogenic as the new top end nikon. Lloyd also shows that shadow noise compromises colour quality on low contrast pictures.

Unfortunately the D3x is too expensive for me, at least right now. It may take a D4 or a d700x to make me buy it.

Until then I use my Zeiss lenses on my Canon 5d via adapter and wait for a more affordable camera to come along.

But I have to admit that the D3x may be the first Nikon that really impresses me in terms of image quality.  The 5d has always been an "almost there"- camera to me. Impressively sharp, but a bit weak on colour and vulnerable highlights.

regards
bernie
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Guillermo Luijk
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« Reply #14 on: February 16, 2009, 05:34:17 PM »
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Quote from: Ray
It's conceibable to me, that Canon have made a decision with regard to in-camera processing of ISO 3200 images, to preserve the maximum dynamic range that the signal allows. At lower ISOs, Canon are probably applying different tone curves, and other adjustments, to make the image look as pleasing as possible, but at the sacrifice of some degree of DR.

Does that make sense?
I wouldn't try to match conclusions about DR from different sites following so different criteria Ray. I think DPreview rely too much on the preadjusted modes (both JPEG camera modes or ACR RAW settings) when they could just go into the RAW data an measure SNR. But I agree that site is not so technically focused.


Quote from: BernardLanguillier
Indeed. Well controlled highlights, noiseless shadows and a pleasant contrasty curve, without mentioning the fact that this was shot with a T/S lense.
A D3X, with controlled highlights and noiseless shadows. 14-24 and TS lenses. Pano stuff. Moreover you enjoy living in Tokyo.
My conclusion Bernard is that your goal is not photography, but to ruin us all here  
BTW do you have the 24mm PC-E? what could you tell about it in terms of geometric distortion, need to be corrected? and CA and sharpness?


Quote from: alba63
Indeed, the dpreview DR measurings, but also the other sites' numbers for DR are quite confusing, they differ substantially (with DXO mark having the highest numbers) and in the end they don't tell much.
DxO Mark DR figures can be used to comare camera sensors. Moreover they provide the complete SNR curves (called 'Full SNR') that allow you to calculate the DR of any sensor applying your favourite criteria (they use the SNR>0dB criteria which is not very demanding, yielding such high DR figures).

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Ray
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« Reply #15 on: February 16, 2009, 06:10:26 PM »
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Quote from: GLuijk
I wouldn't try to match conclusions about DR from different sites following so different criteria Ray. I think DPreview rely too much on the preadjusted modes (both JPEG camera modes or ACR RAW settings) when they could just go into the RAW data an measure SNR. But I agree that site is not so technically focused.

I guess one has to appreciate the fact that Dpreview tries to cater to the needs of the majority of all those who buy cameras, including P&S cameras. I believe the majority of people who use cameras shoot in jpeg mode, as recommended by Ken Rockwell   .

I think it's probably true also that more photographers use ACR than any other single RAW converter.
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Guillermo Luijk
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« Reply #16 on: February 16, 2009, 06:29:47 PM »
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Quote from: Ray
I guess one has to appreciate the fact that Dpreview tries to cater to the needs of the majority of all those who buy cameras, including P&S cameras. I believe the majority of people who use cameras shoot in jpeg mode, as recommended by Ken Rockwell   .

I think it's probably true also that more photographers use ACR than any other single RAW converter.
   


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BernardLanguillier
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« Reply #17 on: February 16, 2009, 08:30:39 PM »
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Quote from: GLuijk
A D3X, with controlled highlights and noiseless shadows. 14-24 and TS lenses. Pano stuff. Moreover you enjoy living in Tokyo.
My conclusion Bernard is that your goal is not photography, but to ruin us all here  

Tokyo is the place to be these days, but the fact is that I only need good gear to compensate for my poor shooting skills.

Speaking of panos, I just came up with a 510 megapixel monster with infinite DoF (172 images involved in this photographic orgy) that should print nicely in 2.5x1 m at 360DPI.

Quote from: GLuijk
BTW do you have the 24mm PC-E? what could you tell about it in terms of geometric distortion, need to be corrected? and CA and sharpness?

It takes about a +3 correction in PS lens correction module to totally get rid of distorsion on the 24 PCE, +2 does most of the job when the lens is not shifted too far out.

Sharpness is excellent on my sample and I have not noticed any outrageous CA, but haven't really been looking too thoroughyl either.

I have been using the 24 T/S as my regular wide angle lens on many assignements, even when I don't necesseraly need the T/S capability.

Cheers,
Bernard
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NikosR
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« Reply #18 on: February 17, 2009, 03:17:08 AM »
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I'll be the last to defend dpreview. However, I always wish to be accurate when commenting on something and I also seek to find out why things appear to be they way they do. People who have started this thread should have noted and mentioned that dpreview 'measures' DR using the camera's default jpeg settings (FWIW). Any default High ISO noise reduction applied to the higher ISO images could have an effect of increasing apparent DR (resolution loss not withstanding) by lowering the noise floor. In fact, washing out all detail by applying an extreme NR would indeed raise DR the way Dpr is measuring it.

So one can bash the method by which dpr are measuring DR (and he would be very right to do so) but he should at least report the facts completely and accurately.
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Nikos
Guillermo Luijk
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« Reply #19 on: February 17, 2009, 09:14:35 AM »
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NikosR, did you spend the same time as here in writing to the DPreview team to let them know they are providing non advanced users with misleading figures because they consider noise reduction as a DR enhancer? (which BTW is just another evidence of how surrealistic their analysis are).

Because I think that is by far much more important than the completeness and accuracy of this thread.
« Last Edit: February 17, 2009, 09:16:41 AM by GLuijk » Logged

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