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Author Topic: 5D3 same max dynamic range as the 5D2???  (Read 29124 times)

LetTheRightLensIn

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #75 on: March 09, 2012, 04:36:13 PM »
Ok, let's go back to the beginning.

Assuming the side masking area can be used for the measurement then:

I contend that the above assumption is invalid, and it's the assumption on which the conclusion is based.  Do you have data to support the assumption that the side masking area's signal value and standard deviation are representative of the portions of the sensor that are actually used to record the image?  I've got an open mind about this, but I must confess, I get really suspicious when someone 'measures' numbers in a system where a log2 scale is commonly used, and the resulting values are exact integer results of 2n

EDIT:  You've got a 5DII, right?  So, can you shoot a black frame (lens cap on) and compare the ISIS data from the masked edge with the center of the frame?

The version of IRIS out now understands the 5D2 so I can't seem to let it show the masking area. It sort of reads in 7D files although only a really small chunk, it does reveal some of the masking area, on my 7D the black levels are the same masking or central area as expected, the read noise is slightly different but close, tested it at ISO100 and ISO6400, very roughly 5% difference. I believe people found similar for the 5D2. It was a few years back I forget the exact details.

If we took the best scenario from and decided that the read noise should be 5% better (although on my 7D at ISO100 it was actually 5% worse in the main sensor area) and that the max raw level should have actually been 16384 max 14bit value then we still only get 11.3 stops (versus 11.1 stops).

Maybe the read noise in the masked area will vary by far, far more this time. I hope so. It seems more likely that it won't than it will though.

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #75 on: March 09, 2012, 04:36:13 PM »

LetTheRightLensIn

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #76 on: March 09, 2012, 04:48:18 PM »
@LetTheRightLensIn: Perhaps we are not referring to the same sources of information and data. I can no longer tell, based on statements about low ISO DR having not improved from 5D II to 1D IV (which as far as I can tell from DXO data, it did. 5D II screen DR 11.16, 1D IV screen DR 11.46; 5D II print DR 11.86, 1D IV print DR 11.95.

Yes 11.95 > 11.86 but that could easily be within margin on camera to camera sample variation and even if the difference is .09 or even .2. Can anyone really tell the difference between a camera with .09 or .2 stops more DR? That's meaningless in the real world. And that was my point, no meaningful DR improvement at base ISO since the 1Ds3.

I hoped the 5D3 would change that. Unless the masking area works a lot differently this time (it is possible, which is we have been asking for people with 5D3 to provide full black frames, but so far nobody has provided them, but not too likely) then it seems the 1DX is the only hope. I hope it does since it would at least prove that Canon is capable of improving this. But it sure would suck if they left it out of the 5D3 after all of these years and then they charge $500 more than the D800 on top. On paper at least, they did knock the 5D3 out of the park, but if they did have the better DR tech, it kinda stinks to charge so much more and not use. Anyway that is all speculation.

I do await the DxO tests. Very curious to see, especially, how the SNR measurements turn out. People have had a go at it and it looks like 2/3rds stop better, not bad, but this is tricky to measure and could be well off so I really await DxO for that.



Quote
To put it simply, those pixels are specialty cases either for setting black point and/or calibration, and cannot reliably be used as a basis for minimum signal (there are some statistics about deviation around the base 1024 value they tend to have that you might be able to use to deduce a true dark frame minimum signal level...but even so, any conclusions based on such a measurement would not be particularly reliable as I'm not sure anyone fully understands those pixels.)

True, but when they were used in the past on a few cameras the ended up giving results within a tenth of a stop or so, which is plenty close enough, it's within margin of camera to camera sample variation and way, way, way below what would matter to anyone using the cameras, but maybe something changed this time, although they appear to look about the same as on the 7D though so that seems unlikely, we will see.

I agree that a true black frame would be preferable but the masking area seemed work well enough a few times before.

LetTheRightLensIn

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #77 on: March 09, 2012, 04:57:42 PM »
And who on Earth needs (emphasis intentional) that many stops of shadow recovery anyway?

Folks can argue back and forth about the validity of the tests and the sample size of one.  I get that.  This sentiment I don't get. 

As a landscape shooter I routinely expose as far to the right as I can and still encounter images where I need to draw considerable detail out of the darkness.  It isn't the least bit uncommon to encounter scenes where the dynamic range easily exceeds the capabilities of my 5D2's sensor.  This is, after all, why many photogs embrace HDR. 

If Sony can figure out a way to reduce the need to rely on HDR by providing greater dynamic range within a single capture, I expect Canon to be just as competent.  It's not like they don't have the resources to compete.

Exactly. I don't know why some people keep going on about just learn how to exposure properly. It has nothing to do with that. Of course people aren't making a big deal about it just to get around not learning how to take photos!

It simply means that if your scene has more than about 10 stops of DR then it won't be able to be captured, you either have to live with blowing out bright parts or sending potentially important parts of the image to pure black.

Sometimes a filter can help darken the sky, keep the bottom part bright, but sometimes the light and dark don't match any filter pattern. Sometimes multiple shot can help although if you don't have tripod with you meshing them sometimes results in a bit of loss but ok always bring a tripod but even then sometimes things are blowing or swirling or moving around too much.

(and if something went wrong and the exposure was messed up on some one of shot, that you won't be able to rescue it as well)

So people shoot stuff where it will almost never matter at all, and fine, the threads on it have no meaning for them, excellent. Some people do shoot stuff will it might matter, or would like to be able to too, on occasion or even semi-frequently, for them it may matter.

if you never wnat to shoot stuff like that or are happy just avoiding stuff that can't work then fine, nobody says you have to be upset about lack of DR. For quite a few people this thread may have zero bearing on them whatsoever and that is awesome, but don't snidely attack those for whom it might. And even for those who would like more it hardly means we will throw our cameras in the trash they are still awesome for all that they can do!

Anyway I've said all that can be said so until we get black frames I have nothing more to say here.

Maybe they feel they don't even need to compete since if they see it brought up and someone get +2 and -30 each time what do they think but hey why bother lets just keep milking our old production designs. How do you get their attention if any attempt get smit down or troll-called in every forum.

Also possible is that Sony has the digital column parallel ADC so heavily patented up that the problem may be intractable for everyone else :( and that Canon has been trying their best and that the tech they reported turned down years ago was turned down for legit reasons and not a few bucks savings. It is possible it is not the tiniest bit their fault. But that is sort of an even worse answer. Maybe there are split reads or some other methods perhaps though? Maybe if they eventually swithc to some radically new sensor tech it will be a new game?
« Last Edit: March 09, 2012, 05:33:29 PM by LetTheRightLensIn »

neuroanatomist

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #78 on: March 09, 2012, 04:58:37 PM »
measuring a block in the masked off area where no light hits

Can you provide some evidence that those areas are physically masked?  Because I don't believe that's the case. Based on geometry, light from the lens covers the whole sensor. So unless Canon has covered those pixels with opaque material instead of microlenses, they are being hit by light.  If so, the 'dark reading' you're getting from them is totally artificial, as is the noise (SD) measured there - and thus, any determination of DR based on those values is meaningless.

I've raised this point a bunch of times, with no response. That suggests to me you 1) don't understand the point (very unlikely), 2) don't buy the argument (possible, but a rebuttal would have been appreciated), or 3) understand and accept the argument but have no logical response other than admitting a flawed methodology, so you're choosing to say nothing instead. Regardless, I'm done arguing the point. As discussed above by me and several others, this is a totally moot point until a production 5DIII is available for testing. 
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LetTheRightLensIn

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #79 on: March 09, 2012, 05:02:54 PM »
measuring a block in the masked off area where no light hits

Can you provide some evidence that those areas are physically masked?  Because I don't believe that's the case. Based on geometry, light from the lens covers the whole sensor. So unless Canon has covered those pixels with opaque material instead of microlenses, they are being hit by light.  If so, the 'dark reading' you're getting from them is totally artificial, as is the noise (SD) measured there - and thus, any determination of DR based on those values is meaningless.

I've raised this point a bunch of times, with no response. That suggests to me you 1) don't understand the point (very unlikely), 2) don't buy the argument (possible, but a rebuttal would have been appreciated), or 3) understand and accept the argument but have no logical response other than admitting a flawed methodology, so you're choosing to say nothing instead. Regardless, I'm done arguing the point. As discussed above by me and several others, this is a totally moot point until a production 5DIII is available for testing.

They are good points and I worried about them too the first time I saw someone suggest using the masking area since we had nothing else to go on at the point when this came up with the prior round. But for the cameras tried it seems to work to within a degree that is good enough.

As for light leaking, I did wonder, but as I said on my 7D, the read noise tends to be slightly lower, like 5%, not higher as would be expected if light were leaking in. The sealing may be super tight or maybe they somehow don't have them actually reading from a live well or something. I really don't know.

And yes I'm outta here too. I've defended myself enough. It wastes too much time and I'm tired or arguing and if all people want to do is attack and throw accusations and with 30 smites for each applause why the heck should I ever bother posting about anything anyway, or at the least why bother going on and on in defense and offering explanations. If I do post more I will simply post and be done with it and not respond and everyone can say whatever they want after that :D.
« Last Edit: March 09, 2012, 05:10:07 PM by LetTheRightLensIn »

te4o

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #80 on: March 09, 2012, 07:37:11 PM »


And yes I'm outta here too. I've defended myself enough. It wastes too much time and I'm tired or arguing and if all people want to do is attack and throw accusations and with 30 smites for each applause why the heck should I ever bother posting about anything anyway, or at the least why bother going on and on in defense and offering explanations. If I do post more I will simply post and be done with it and not respond and everyone can say whatever they want after that :D.
[/quote]

@LTRLI (too long to spell) I applauded you for your open mind and for the boldness you have to oppose so many fans. You explained in good detail what you found and your conclusions are logical. I understand them as a warning against too high expectations for the new sensor at low ISO. However, giving an opinion about this sensor without a single production camera available, without the proper final RAW software, and without using them both yourself makes this just an approximation and a topic of interest for further research. Nothing more.
Good to learn about "masking area" though. I'd love to see your results from the lens-cap-black-frame-test.
Don't be disappointed by opposition, Nietzsche says "there are many disappointed good 'men' standing in the way of progress..."
To all the rest, I think people like LTRLI are helpful to increase our own personal DR :D.
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sarangiman

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #81 on: March 10, 2012, 12:05:34 AM »
Heck I gave you all +1's! I think all the arguing back & forth is great, as there is a lot to learn/understand! As long as we're civil about it :)

I have a # of questions, especially for LTRLI, neuroanatomist, & jrista:

(1) If Canon claims quantum efficiency is up due to better microlens design, and if initial tests show better ISO performance for the MkIII vs the MkII with RAW files (i.e. no influence of noise reduction, hopefully), then doesn't all that mean that SNR is necessarily higher? And doesn't higher SNR necessarily mean greater DR, for the same general sensor design (assuming nothing actually got *worse* btwn the MkIII & MkII)? Am I missing something here?

(2) Let's say those masked pixels really are sealed/blocked off from light OR are somehow turned off. However, let's say they're still being read by the electronics & so they can still be an indication of dark noise. Then, you use:

Equation 1:     DR = log(base 2) [highest signal/stdev]

But for that calculated DR to be indicative of the max possible DR of the scene being recorded -- doesn't that presuppose a linear relationship between incoming light & recorded signal in the RAW file? Do we know this to be true?

(3) Related to question (2)... Has anyone actually established that Equation 1 is a standard, accepted, measure of DR? DXO says "Dynamic range is defined as the ratio between the highest and lowest gray luminance a sensor can capture"... note it doesn't say "... a sensor records". Again, assuming a linear relationship between incoming light & signal recorded (which is not true, for example, for film) in the RAW file, I guess this'd be the same. But but from DXO's testing methodology description (http://www.dxomark.com/index.php/About/In-depth-measurements/DxOMark-testing-protocols/Noise-dynamic-range), I thought they were using actual light source/ND filter combinations to measure the SNR & DR.

(4) I must say I find it strange that in DXO's methodology in the link above, they state that they use a setup "in order to test across a dynamic range of 4 density steps (= 13.3 f-stops — a dynamic range much greater than today’s digital cameras)"... but then report that the Nikon D7000 has 13.9 stops of DR. Is this just an outdated description?

Thanks in advance!

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #81 on: March 10, 2012, 12:05:34 AM »

sarangiman

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #82 on: March 10, 2012, 02:16:21 AM »
I went back to the book 'Image Sensors and Signal Processing for Digital Still Cameras' and it speaks of the 'optical black' (OB) pixels around the active pixels that are necessary to determine a proper black level. I'm assuming that, by whatever mechanism, they have no light gathering capability (b/c, as neuroanatomist mentioned, light from the lens can fall on those pixels).

So, if those OB pixels are used to determine the black level, they may also reflect the noise generated by the read event & subsequent electronics. It is, however, curious that they're around 1024 for the 5D II & 2048 for the 5D III. That's highly suspicious... I'd love to know what Canon is doing there. Isn't that # roughly what the black level is set to? If so, I don't think you'd want to be setting the black level to ~2048... seems to me that'd lower DR... unless the blackest pixel in the Active Pixel area really has a lowest level of 2048 (seems highly unlikely).

I have to go back to dcraw & see what it sets as default black level for my 5D II.

Still, my other problem with this methodology is that recorded signal in the RAW file does not necessarily reflect input signal until someone shows this relationship is completely linear... at least that's what I think.

Ricku

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #83 on: March 10, 2012, 02:59:47 AM »
I saw this chart in another thread, and it looks like the D800 is the new DR king for sure.


The 5D3 and D800 are pretty much comparable, but only at ISO800 and above.. Below ISO 800, the D800's DR is heading sky high, setting a new record.
« Last Edit: March 10, 2012, 03:13:18 AM by Ricku »

torger

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #84 on: March 10, 2012, 03:30:47 AM »
Numbers are hard to interpret, there are so many factors that don't show in a number. No measurement so far I've seen take noise quality (pattern etc) into account, which has a huge impact on subjective DR.

Even if 5Dmk2 and 3 measure the same, if pattern noise is less than usable DR will be better.

High ISO measurements often miss out on quantum efficiency and can be misleading due to that.

A test that I would like to see is mk2 and mk3 shooting the exact same test scene perfectly ETTR, and then push a shadow area (preferably containing a color checker) 3 stops and show the crops side by side, resolution is almost the same so no sacling is required. I suspect/hope that the mk3 will fair much better in such a test than these measurements indicate.

DavidRiesenberg

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #85 on: March 10, 2012, 05:10:33 AM »
I saw this chart in another thread, and it looks like the D800 is the new DR king for sure.


The 5D3 and D800 are pretty much comparable, but only at ISO800 and above.. Below ISO 800, the D800's DR is heading sky high, setting a new record.

If this chart is true and not a result of some miscalculation, that would indicate that the D800 applies some sort of artificial curve to balance the shadows and highlights. An aggressive HTP sort of thing.

sarangiman

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #86 on: March 10, 2012, 05:54:32 AM »
Quote
High ISO measurements often miss out on quantum efficiency and can be misleading due to that.

Why is that (mechanistically)?

Quote
A test that I would like to see is mk2 and mk3 shooting the exact same test scene perfectly ETTR, and then push a shadow area (preferably containing a color checker) 3 stops and show the crops side by side

Why can't you do that with the RAW files posted for both cameras on Imaging Resource right now yourself? There's a Color Checker in those shots.

Quote
If this chart is true and not a result of some miscalculation, that would indicate that the D800 applies some sort of artificial curve to balance the shadows and highlights. An aggressive HTP sort of thing.

HTP purposefully underexposes the shots (physically), & then applies a non-linear curve. If the methodology used in generating that graph for the D800 is similar to the method LTRLI used, then any sort of non-linear manipulation done after the exposure would not change the resulting calculated DR (b/c the end points of any non-linear curve would likely still be the same as for the linear curve, since there's no reason to change the absolute values of saturation or black). So I don't think that explains it.

torger

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #87 on: March 10, 2012, 06:17:56 AM »
Waiting for raw support in my raw processor before I can do investigations myself.

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #87 on: March 10, 2012, 06:17:56 AM »

KeithR

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #88 on: March 10, 2012, 08:06:38 AM »
This is, after all, why many photogs embrace HDR. 

Exactly my point - you don't need the camera to provide 6 stops of adjustment.

And I'll reiterate: how much you can get out of the shadows depends massively on the choice of converter, and some people just aren't prepared to put the effort in to find the best converter for all their needs.

If you need deep shadow recovery without banding, use a converter that can do it. They exist.

It's a damn' sight cheaper than jumping ship, and a damn' sight less stressful than the photographer wasting his life away waiting for Canon to produce the perfect camera.

Maybe I'm unusual in this, but I actually enjoy the challenge of finding solutions to problems: it's a far more productive way to use my time than endlessly complaining about this thing or that on internet forums.

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #89 on: March 10, 2012, 08:11:56 AM »
The 5D3 and D800 are pretty much comparable, but only at ISO800 and above.. Below ISO 800, the D800's DR is heading sky high, setting a new record.

Bill Claff, whose site this is from, is a long-time fervent Nikon guy; and these graphs are based on estimated values for both the D800 and the 5D Mk III.

Big pinch of salt in order here...

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Re: 5D3 same max dynamic range as the 5D2???
« Reply #89 on: March 10, 2012, 08:11:56 AM »