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Author Topic: "Nikon D800 / D800E First Comparison"  (Read 54844 times)
marcmccalmont
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« Reply #80 on: April 24, 2012, 05:02:41 PM »
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Bart
I wish you could design a pseudo random pattern and then compare the 2 cameras
Marc
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Marc McCalmont
BartvanderWolf
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« Reply #81 on: April 24, 2012, 05:47:44 PM »
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How do you explain those areas in D800 I pointed to? Some kind of green/orange amebas, blots? Those do not exist in D800e.

Hi Slobodan,

Those are areas where, probably due to the specific alignment with the pixel grid, the demosaicing failed. They all happen at 45 degrees off normal, which suggests that the angle and specific level of detail triggers that behavior. Due to the target being so ordered and predictable to human vision, anything unpredictable will stand out like a sore thumb. In an ordinary image it would not happen or not get noticed.

To eliminate the possiblity of a mapped out (cluster of) sensels being the cause, one can verify in another Raw converter, which I did. They all make different trade-offs, and goof-ups. Capture One tends to push the hunt for detail a bit further than e.g. Lightroom/ACR, and on rare occasions it fails.

Cheers,
Bart
« Last Edit: April 24, 2012, 05:51:31 PM by BartvanderWolf » Logged
dds
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« Reply #82 on: April 24, 2012, 06:23:19 PM »
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Thank you Bart and Michael for these tests.

From my point of view, they pretty much close the debate. The results you have given us serve to separate out actual resolution from the "impression" of sharpness that can be created by aliasing artifacts. There is apparently virtually no real detail increase as a result of eliminating the aliasing filtration.

Now I'm very interested in your investigations into optimal sharpening routines...
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BartvanderWolf
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« Reply #83 on: April 24, 2012, 06:31:59 PM »
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I wish you could design a pseudo random pattern and then compare the 2 cameras

Hi Marc,

Nah, random targets are too easy Wink

Just kidding. Random targets are indeed also used for resolution testing (uniform/white noise and Fourier analysis), but they require a lot of number crunching to get some sensible data out of them. An ordered target can already be evaluated with simple means, sometimes even just visual inspection.

Nevertheless, keep in mind that the target tests the extremes, with a good lens, perfectly focused. Every deviation will show. Real life is often more forgiving.

Cheers,
Bart
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Slobodan Blagojevic
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« Reply #84 on: April 24, 2012, 06:44:26 PM »
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... Those are areas where, probably due to the specific alignment with the pixel grid, the demosaicing failed. They all happen at 45 degrees off normal, which suggests that the angle and specific level of detail triggers that behavior. Due to the target being so ordered and predictable to human vision, anything unpredictable will stand out like a sore thumb. In an ordinary image it would not happen or not get noticed.

To eliminate the possiblity of a mapped out (cluster of) sensels being the cause, one can verify in another Raw converter, which I did. They all make different trade-offs, and goof-ups. Capture One tends to push the hunt for detail a bit further than e.g. Lightroom/ACR, and on rare occasions it fails...

Then again, how come that D800e does not have any?
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bjanes
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« Reply #85 on: April 24, 2012, 06:52:55 PM »
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Hi Marc,

Nah, random targets are too easy Wink

Just kidding. Random targets are indeed also used for resolution testing (uniform/white noise and Fourier analysis), but they require a lot of number crunching to get some sensible data out of them. An ordered target can already be evaluated with simple means, sometimes even just visual inspection.

Nevertheless, keep in mind that the target tests the extremes, with a good lens, perfectly focused. Every deviation will show. Real life is often more forgiving.


Bart,

How about the Dead Leaves model? Have you investigated it?

Regards,

Bill
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BartvanderWolf
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« Reply #86 on: April 24, 2012, 06:55:18 PM »
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Then again, how come that D800e does not have any?

Higher contrast at those spatial frequencies?

Cheers,
Bart
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marcmccalmont
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« Reply #87 on: April 24, 2012, 08:42:40 PM »
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Bart,

How about the Dead Leaves model? Have you investigated it?

Regards,

Bill

Seems like a very good test!
Marc

ps in my audio background if tests don't correlate to what you are hearing with enough diligence you found the flaw in the test and corrected it. My eye says that there is a sharper image without an AA filter and I rarely see false information. Perhaps it is this dead leaf test that the photographic industry is missing?
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Marc McCalmont
Ray
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« Reply #88 on: April 24, 2012, 08:48:49 PM »
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How about the Dead Leaves model? Have you investigated it?

Hi Bill,
That's an interesting article which adderesses some of the concerns that I have about the possible benefits of the D800E when considering real-world images, across the entire tonal range, from highlights to deep shadows, where certain parts of the image may contain fine texture at different levels of contrast and different levels of exposure.

I'm reminded of conparisons I made some years ago between telephoto lenses with and without teleconverter. Sometimes, there seemed to be no benefit in using the teleconverter, or hardly any benefit. But sometimes there was a clear benefit. The results seemed to depend on the contrast and general clarity of the subject. With the use of the teleconverter, well-lit, contrasty texture in the subject seemed to be captured with noticeably more detail, due to the greater magnification, whereas faint and low contrast detail was more easily lost.

The analogy I'm drawing here is that it seems possible that certain low-contrast fine detail and texture, in certain parts of an image, at certain exposure levels, may be captured by the D800E, but irretrievably lost when using a D800.

ps. I forgot to add, when photographing a resolution test target containing black and white lines, the telephoto lens with converter attached always provided greater resolution than the lens without converter.
« Last Edit: April 24, 2012, 09:08:52 PM by Ray » Logged
RobertCubit
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« Reply #89 on: April 24, 2012, 08:53:22 PM »
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Attention - these charts were run with the wrong gamma setting in Imatest

Please see this post for corrections:



To end the speculation, let's look at an actual conversion I made from 2 files, one from the D800, and one from the D800E.
Michael made sure that the test chart was perfectly focused, selecting the best from a focus series for each camera. The same 85mm f/1.4 lens was used at f/4 on both cameras.

Cheers,
Bart

Thanks Bart!

That's about the most useful data I've seen to date on any forum. I've taken the liberty of doing a quick and dirty run of the slant edge patterns on your downloaded png charts through Imatest Studio (version 3.9 Beta). These were completely unmolested (no sharpening etc.). I suspect Erik may be doing the same about now? I didn't have the true chart contrast to enter in the settings or know the quality of the edge transistions on the (printed?) chart (but they looked pretty clean). I did enter gamma at 2.20. There is a screen capture of the Imatest settings page at the end. If anyone has suggested changes to the settings, it's easy enough to renun the charts.

The horizontal and vertical edge profile are nearly identical between the D800 and the D800E. However as expected, the D800 shows lower contrast at higher spatial freqencies near Nyquist. I couldn't run a noise analysis because Imatest complained that the area was too small (this is probably not the best chart for evaluating noise anyway). The chromatic aberration tests are also interesting.

Since I'm not using Imatest for profit, I'll leave the necessary props for Normen Koren and company:

http://www.imatest.com/

My only remaining concern is how much noise may be apparent in images from the D800 after various sharpening routines are applied to boost the low-contrast, high spatial frequency portion of the MTF plot to match the D800E?


D800 MTF horizontal slant edge




D800 MTF vertical slant edge




D800E MTF horizontal




D800E MTF vertical




D800 chromatic aberration horizontal




D800 chromatic aberration vertical




D800E chromatic aberration horizontal




D800E chromatic aberration vertical




Imatest settings for all tests




Hope others find this useful---or at least entertaining!

Kind regards,
Bob

Edit: Correction---this was done in Imatest version 3.9 Beta, not 3.8 Beta. Imatest have not yet updated the version reported on the charts (at least not in Imatest Studio).
« Last Edit: April 29, 2012, 03:02:51 PM by RobertCubit » Logged

bjanes
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« Reply #90 on: April 24, 2012, 09:45:23 PM »
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To end the speculation, let's look at an actual conversion I made from 2 files, one from the D800, and one from the D800E.

Michael made sure that the test chart was perfectly focused, selecting the best from a focus series for each camera. The same 85mm f/1.4 lens was used at f/4 on both cameras.

Bart,

Very interesting results. The Moire is worse than I would have imagined, but then I had never seen your target without low pass filtering. I eagerly await your additional analysis. Where did you get the images? Did Michael post them publicly?

Regards,

Bill
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ErikKaffehr
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« Reply #91 on: April 24, 2012, 11:39:14 PM »
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Hi,

A great lot of thanks to Michael and also for your analysis. Are those raw images available for download?

Best regards
Erik

To end the speculation, let's look at an actual conversion I made from 2 files, one from the D800, and one from the D800E.
Michael made sure that the test chart was perfectly focused, selecting the best from a focus series for each camera. The same 85mm f/1.4 lens was used at f/4 on both cameras.

For this pair I used Capture One Pro v6.4, set to a linear filmcurve, shifted the exposure up a bit, and I only corrected for Chromatic Aberration (to compare with other converters, more on that later), and applied no sharpening at all. The sharpening was skipped to avoid speculation about the effect of different types of sharpening, and it wouldn't have made any difference to the actual limiting resolution anyway. It also allows to determine the best capture sharpening settings.
 
Here are the cropped results, 8-b/ch JPEGs at 100% quality converted to sRGB, at 100% zoom without resampling.
Remember, these are without sharpening.

First the D800:

Click here for a 16-bit/channel PNG version, AdobeRGB as source, Gamma 2.20

Next the D800E:

Click here for a 16-bit/channel PNG version, Adobe RGB as source, Gamma 2.20

I'll elaborate a bit more on the relevant parts in subsequent posts, but I'll already tell that the D800 shows a limiting resolution of 93.9 cycles/mm or 92.0% of Nyquist, and the D800E shows a limiting resolution of 94.9 cycles/mm or 92.9% of Nyquist. In other words, their limiting resolutions are virtually identical which makes sense because the sampling density is also identical. The OLPF in the D800 only reduced the amplitude of the MTF, which helped to reduce aliasing and demosaicing artifacts.

Cheers,
Bart
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Guillermo Luijk
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« Reply #92 on: April 25, 2012, 02:11:19 AM »
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I'll elaborate a bit more on the relevant parts in subsequent posts, but I'll already tell that the D800 shows a limiting resolution of 93.9 cycles/mm or 92.0% of Nyquist, and the D800E shows a limiting resolution of 94.9 cycles/mm or 92.9% of Nyquist. In other words, their limiting resolutions are virtually identical which makes sense because the sampling density is also identical. The OLPF in the D800 only reduced the amplitude of the MTF, which helped to reduce aliasing and demosaicing artifacts.

Excellent test and conclusions Bart. It seems clear that the D800E doesn't hold more detail, just higher microcontrast that should be recoverable through smart sharpening.

If you were to pick one of the models, which one would you choose with the available information?

Regards
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BartvanderWolf
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« Reply #93 on: April 25, 2012, 04:42:51 AM »
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Thank you Bart and Michael for these tests.

From my point of view, they pretty much close the debate. The results you have given us serve to separate out actual resolution from the "impression" of sharpness that can be created by aliasing artifacts. There is apparently virtually no real detail increase as a result of eliminating the aliasing filtration.

Now I'm very interested in your investigations into optimal sharpening routines...

You're all welcome, it wouldn't have been possible without Micheal's input. The benefit of a higher modulation near the limiting resolution is in better microdetail with low contrast subject. An example would be woodgrain in wooden objects. However, since there is no free lunch, aliasing can get in the way with sharp edges and repetitive structures. The false color (chroma) aliasing from Bayer CFA demosaicing can be dealt with with a good Raw converter, but it remains a challenge for the Raw converter, and it will struggle with luminosity aliasing.

So the advise remains to choose one's weapons for the task at hand, or go with the safer option if you want to avoid a lot of manual postprocessing.

I'm working on the optimal sharpening tool, but I just found an issue that needs to be resolved first.

Cheers,
Bart
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BartvanderWolf
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« Reply #94 on: April 25, 2012, 05:30:42 AM »
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How about the Dead Leaves model? Have you investigated it?

Hi Bill,

Yes, I've read about it, but have not come to a conclusion for myself yet. One of the issues that photographers face in practice are things like unexpected artifacts which then consume a lot of time (=money) to deal with. What I like is that it gives an impression about lower contrast detail resolution, but I'm not so sure yet that the 'dead leaves' target is e.g. enough of a challenge to push the Raw converter over the edge of its demosaicing capabilities in view of aliasing.

It's interesting to see how different Rawconverters tackle that challenge, and I have some very interesting initial results coming from RawTherapee which also allows to influence the "amaze" algorithm's false color suppression. The more 'amazing' result is that it resolves even closer to the Nyquist frequency ... Luminance aliasing remains a limiting factor though.

Cheers,
Bart
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kers
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« Reply #95 on: April 25, 2012, 05:41:40 AM »
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...
For this pair I used Capture One Pro v6.4, set to a linear filmcurve, shifted the exposure up a bit, and I only corrected for Chromatic Aberration (to compare with other converters, more on that later), and applied no sharpening at all. The sharpening was skipped to avoid speculation about the effect of different types of sharpening, and it wouldn't have made any difference to the actual limiting resolution anyway. It also allows to determine the best capture sharpening settings.
...
Bart

Hello Bart,
Thank you and Michael for this interesting test.
I ask myself how different the outcome would be with different Raw converters ...? Especially the software from Nikon self :  Nikon Capture NX2.32
Also would like to know if their moiré tool adds to the image quality.
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Pieter Kers
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BartvanderWolf
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« Reply #96 on: April 25, 2012, 06:11:08 AM »
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Thanks Bart!

That's about the most useful data I've seen to date on any forum. I've taken the liberty of doing a quick and dirty run of the slant edge patterns on your downloaded png charts through Imatest Studio (version 3.8 Beta). These were completely unmolested (no sharpening etc.). I suspect Erik may be doing the same about now? I didn't have the true chart contrast to enter in the settings or know the quality of the edge transistions on the (printed?) chart (but they looked pretty clean). I did enter gamma at 2.20. There is a screen capture of the Imatest settings page at the end. If anyone has suggested changes to the settings, it's easy enough to renun the charts.

The horizontal and vertical edge profile are nearly identical between the D800 and the D800E. However as expected, the D800 shows lower contrast at higher spatial freqencies near Nyquist. I couldn't run a noise analysis because Imatest complained that the area was too small (this is probably not the best chart for evaluating noise anyway). The chromatic aberration tests are also interesting.

Hi Bob,

Thanks for doing the Imatest run, I didn't have the time to do it myself yet. The only change to the settings I could suggest is to replace the crop size setting with the full image size of 7416 x 4916 (which is what some converters squeeze out of the Raw) or the formal 7360 x 4912 pixels.

The various Raw converters I've tried sofar do add a reddish tint to the D800E conversions in varying degrees, interpreted by Imatest as CA.

Quote
My only remaining concern is how much noise may be apparent in images from the D800 after various sharpening routines are applied to boost the low-contrast, high spatial frequency portion of the MTF plot to match the D800E?

Yes, that is still open for debate, also depending on whether one uses ETTR and low ISO settings. It often helps to do a mild noise reduction before applying significant sharpening, and to mask and blend the sharpening with a bias towards luminosity sharpening. Personally I don't worry about the noise too much, but then I'm a low ISO shooter, and things look better inprint that when pixel peeping on a monitor.

Cheers,
Bart
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BartvanderWolf
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« Reply #97 on: April 25, 2012, 06:19:19 AM »
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Very interesting results. The Moire is worse than I would have imagined, but then I had never seen your target without low pass filtering. I eagerly await your additional analysis. Where did you get the images? Did Michael post them publicly?

A great lot of thanks to Michael and also for your analysis. Are those raw images available for download?

Bill, Erik,

They're Michael's files, I was fortunate enough to receive a copy. It's up to Michael how he wants to keep control over them.

Cheers,
Bart
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BartvanderWolf
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« Reply #98 on: April 25, 2012, 06:34:43 AM »
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Excellent test and conclusions Bart. It seems clear that the D800E doesn't hold more detail, just higher microcontrast that should be recoverable through smart sharpening.

If you were to pick one of the models, which one would you choose with the available information?

Hi Guillermo,

Given my personal shooting preferences (including architecture and product photography, but also landscapes and macro), the safest option would be the D800. I'm a bit allergic to aliasing (because it reveals that the fundamental rules of DSP were not taken serious enough), but I've also spent more effort in perfecting my sharpening arsenal of tools than most others have, so restoring sharpness is not that hard. Mind you, even a camera with an AA-filter can fall victim to aliasing, it's usually just a somewhat more benign manifestation, easier to repair.

Cheers,
Bart
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BartvanderWolf
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« Reply #99 on: April 25, 2012, 06:46:55 AM »
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Hello Bart,
Thank you and Michael for this interesting test.
I ask myself how different the outcome would be with different Raw converters ...? Especially the software from Nikon self :  Nikon Capture NX2.32
Also would like to know if their moiré tool adds to the image quality.

Hi kers,

Good questions, and yes there are differences. One of the problems is that they do not only give different results, but also different workflows, and there is more to image quality than resolution versus moiré alone. So it depends a bit on one's goals, ultimate image quality or good enough quality but a more efficient process.

Another thing is that support for the D800/D800E was only recently added to several Raw converters, maybe there is some room for improvement as these solutions mature. I'll try and post some results from different converters if I can find some time, but I don't have Nikon's Capture NX converter.

Cheers,
Bart
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