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Author Topic: "Nikon D800 / D800E First Comparison"  (Read 52596 times)
dds
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« Reply #120 on: April 26, 2012, 04:38:46 PM »
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I can understand why some folks are reluctant to accept what the test results show. But there is only one logical explanation. The use of a good a.a. filter has virtually no effect on the resolution of actual detail, and helps reduce garbage--false detail and color artifacting as well as moire.

In some situations, a D800e will have a very slight advantage over a D800 in areas of fine low-contrast shadow detail. This advantage is not in resolution, but in micro contrast. It can probably be easily compensated for in most situations by the use of good post-processing routines, including deconvolution sharpening. This compensation may be less effective at higher ISO's because of the complication of more prominent noise.

In all honesty, the files I prepare for printing do have artifacts, viewed at 100%. I find that I have to give extra sharpening because of ink bleeding. So my print files are just on the edge of being "crunchy," with an almost invisible mist of grain from the sharpening. They look better that way in the final print. I use deconvolution sharpening and micro contrast to get them to that point.

On the other hand, aliasing artifacts from the camera can also make a file look sharper. It's not real detail, but it looks good at some sizes and at some magnifications, to many people. Files from cameras without a.a. filters need less sharpening and can handle less sharpening.

There are all kinds of sharpness paradoxes in photography. This is nothing new. Grain can make a file (or a negative) print better sometimes. Synthetic edge effects built into color films can make a photograph look sharper. The psychology of sharpness is fascinating. So in some sense there's no such thing as "pure" sharpness. At least not at our current stage of technology.

What I'm saying, I guess, is pick your poison. Do you want to adopt aliasing artifacts because they give an impression of sharpness? Or would you rather dial up your sharpening process a little? I prefer the second alternative, because I can control it. And sharpening software will keep getting better as time goes on, so my original file can be improved. Plus I hate camera artifacts and shoot a lot in the city. But that's just me.

I'm glad to see some of the mythology of a.a. filtration put to rest. There's been a touch of elitism in talking about a.a.-less sensors; an assumed superior knowledge that doesn't correspond to optical theory or, as we are seeing, real life. I'm happy we have choices, and happy that we're learning more about what the choices actually offer us.

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marcmccalmont
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« Reply #121 on: April 26, 2012, 05:36:12 PM »
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I think it was Slobodan who coined the term "Squints" I must have laughed for 10 minutes, a perfect description! Well I guess I am a "LuLu Squint" and proud to be one!...........
After a nice morning walk photographing a beautiful waterfall in Kobe, it dawned on me that we are not talking about resolution we are talking about acutance or the ability of a sensor to define a one pixel line. The test charts clearly showed an increase in resolution of 1% and most dismissed this as negligible. Well acutance is on the pixel level not the global level so lets take a minute to "squint"! so a D800 has 7380 horizontal photo sites, it can resolve 3680 line pairs. and the E model can out resolve the 800 by 1% that is 1% of 3680 lp's. 1% of 3680 is 37 lp's! thats a 3700% difference in acutance!!!! more than an order of magnitude.
Marc
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Marc McCalmont
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« Reply #122 on: April 26, 2012, 05:39:54 PM »
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I can understand why some folks are reluctant to accept what the test results show. But there is only one logical explanation. The use of a good a.a. filter has virtually no effect on the resolution of actual detail, and helps reduce garbage--false detail and color artifacting as well as moire.


This.
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BartvanderWolf
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« Reply #123 on: April 26, 2012, 05:52:43 PM »
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Bart where can I download a copy of your chart?

Hi Marc,

There are a few different versions available depending on which printer one uses, and also a version for the real masochists who want to really stress the Bayer CFA on its weakest point (red/blue resolution with approx. equal luminance).

The targets can be downloaded from the first post in this thread on another website. I usually do not like to draw people away from a forum, but there are also explanations there as to its use and interpretation, and some examples, which I don't like to copy to multiple websites.

Cheers,
Bart
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marcmccalmont
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« Reply #124 on: April 26, 2012, 06:38:03 PM »
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Hi Marc,

There are a few different versions available depending on which printer one uses, and also a version for the real masochists who want to really stress the Bayer CFA on its weakest point (red/blue resolution with approx. equal luminance).

The targets can be downloaded from the first post in this thread on another website. I usually do not like to draw people away from a forum, but there are also explanations there as to its use and interpretation, and some examples, which I don't like to copy to multiple websites.

Cheers,
Bart
Thanks Bart
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Marc McCalmont
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« Reply #125 on: April 26, 2012, 10:39:02 PM »
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The random pattern test MIGHT show the D800e in a slightly better light but it seems to me that test would actually be less revealing of what is going on.  One interpretation of why someone might favour the random pattern test is that it might provide a result that is more to comforting i.e. if someone starts off with a belief that omitting the AA filter is bound to produce better detail, they might deep down inside want testing to show that this is the case - even if we have to choose a very special test to make that happen. Not a very scientific approach but very human ;-)  Personally, I'd prefer to see the unvarnished truth which why I prefer the test as presented.


Random patterns tend to be the norm. Specialised and artificially constructed test  charts are useful to understand what's going on and can provide a degree of certainty.

However, it is quite natural that anyone who is contemplating buying a camera without the usual AA filter, would be more interested in perceived advantages in real-world scenes which are not usually constructed from evenly spaced, black and white lines.

Now it's clear that the removal of the AA filter does put one at risk of occasionally spoiling an image with moire and aliasing artifacts. What I'd like to know is just how effective the Nikon software is at removing such artifacts. Are those, perhaps rare, occasions when moire rears its ugly head, fatal? In removing the moire, does the Nikon software degrade the image so much that the D800 image is clearly superior?

If one is a scientist gathering data which has to be as accurate as possible, the last thing one wants are artificial data created by the measuring equipment.

However, if the purpose of the exercise is to created a pleasing, interesting and/or esthetic image, in the eyes of some, then the presence of artifical data is of little consequence unless it is visually jarring or obtrusive.

To take an extreme example, I have very few strands of hair on my head. If someone were to shoot a portrait of me using a camera without an AA filter, and such camera were to create additional strands of hair due to its capacity to (apparently) resolve beyond the Nyquist limit, would I be angry and furious?  Grin
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Rob C
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« Reply #126 on: April 27, 2012, 02:39:55 AM »
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To take an extreme example, I have very few strands of hair on my head. If someone were to shoot a portrait of me using a camera without an AA filter, and such camera were to create additional strands of hair due to its capacity to (apparently) resolve beyond the Nyquist limit, would I be angry and furious?  Grin



If you hear any further news on such 'positively discriminatory' cameras, would you be kind enough to pass it on?

;-)

Rob C
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Sareesh Sudhakaran
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« Reply #127 on: April 27, 2012, 04:27:56 AM »
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I have a question: The Nyquist rate for the D800 sensor is much higher than has ever been seen before in a FF sensor, as the M9 sensor is 'only' 16MP. Shouldn't the chances of moire be much lesser in the case of the D800E since it resolves a lot more?
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« Reply #128 on: April 27, 2012, 05:40:57 AM »
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I have a question: The Nyquist rate for the D800 sensor is much higher than has ever been seen before in a FF sensor, as the M9 sensor is 'only' 16MP. Shouldn't the chances of moire be much lesser in the case of the D800E since it resolves a lot more?
Aliasing happens whenever there is significant signal beyond half the sampling rate. This manifests itself as spurious errors in the digitized signal that can appear at any frequency (e.g. very low frequency). Moire (used in this context) is just the visible periodic errors that appears when there is a periodic pattern in the scene that happens to trigger significant aliasing at the sensor.

If the lense, scene, recording technique etc is scaled accordingly, aliasing should be as likely on a 2MP sensor as a 180MP sensor. Of course, those factors usually does not scale lineary with sensel count, but it seems that many photographers do their best in order to make it so.

In short: perhaps, but not necessarily.

-h
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BartvanderWolf
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« Reply #129 on: April 27, 2012, 10:59:45 AM »
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I have a question: The Nyquist rate for the D800 sensor is much higher than has ever been seen before in a FF sensor, as the M9 sensor is 'only' 16MP. Shouldn't the chances of moire be much lesser in the case of the D800E since it resolves a lot more?

Hi Sareesh,

If everything else is the same, a higher sampling density will indeed reduce the risk of aliasing artifacts.
Aliasing artifacts can only be avoided by increasing the relative size of the finest image detail to more than twice the sampling pitch, and/or by reducing the contrast of the image detail far enough.

It will probably require a sub-micron sensel pitch to avoid aliasing without additional help. 

Cheers,
Bart
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« Reply #130 on: April 27, 2012, 05:56:52 PM »
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Attention - these charts were run with the wrong gamma setting in Imatest

Please see this post for corrections:



Hi Bart,

Thanks for doing the Imatest run, I didn't have the time to do it myself yet.

Glad to help.

Quote
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.

Good point. I noticed that after posting. I usually work with the raw files with embedded exif data that automatically fills in most of the image parameters. I've re-run the horizontal profile charts using your 7416 x 4916 image dimensions. Of course, this did not change the key, edge profile results or SFR (MTF) plots from the original run. But the results that depend on picture height (PH) such as LP/PH are now valid. I've also added the Acutance charts since they are another important metric of Subjective Quality Factor (SQF), as was mentioned in another post. As a newbie on this forum, I'll add another very soft request for access to the original raw files, if and when Michael can spare the time and bandwidth? (Maybe there is something in the background of the full frame captures that he doesn't want to distribute on the web---perhaps one of those infamous Secret-Service style orgies rumored to go on in the Lu-La studio after hours?! Smiley)

After a bit of additional research, my feeling on the Dead Leaves pattern method is that the random, variable-contrast edges may indeed be useful in determining how much of the low-contrast, fine detail might be permanently lost below the noise floor on the D800 (especially at higher ISO), relative to the D800E. The Dead Leaves pattern is similar in concept to the Random (Scale-Invariant) patterns discussed by Imatest:

http://www.imatest.com/docs/random/

Imatest master will analyze both patterns. I haven't tried this method, yet.

Quote
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.

That's interesting---maybe those converters are not completely “baked” yet? My thought was that Imatest was just detecting the additional color aliasing apparent in the D800E image, at spatial frequencies beyond Nyquist.

Quote
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.

That pretty much describes me as well. As a landscape and macro shooter, I shoot at near base ISO perhaps 90% of the time. That said, there are times such as when shooting long-stemmed lupine at twilght out in the ever-windy foothills of the Eastern Sierra Nevada mountains in California, that the option to boost the ISO to enable faster shutter speeds can sure be useful!

_______________________________________________________________________________

Second run with Imatest 3.9 Beta with corrected pixel dimensions.

D800E SFR


D800E SRF LP/PH


D800E Acutance


D800E Chromatic Aberration


D800 SFR


D800 SRF LP/PH


D800 Acutance


D800 Chromatc Aberration


Imatest Settings




Results generated by Imatest Studio 3.9 Beta

http://www.imatest.com/


Kind regards,
Bob
« Last Edit: April 29, 2012, 03:05:32 PM by RobertCubit » Logged

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« Reply #131 on: April 28, 2012, 01:44:05 AM »
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Why is it that the chromatic abberation on the d800e result is so much worse than with the d800? Huh
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« Reply #132 on: April 28, 2012, 01:44:28 AM »
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Perhaps someone would provide a summary of the acutance difference between the two cameras for those of us not familiar with interpreting imatest charts
Thank
Marc
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Marc McCalmont
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« Reply #133 on: April 28, 2012, 03:27:49 AM »
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Why is it that the chromatic abberation on the d800e result is so much worse than with the d800? Huh

Because it is not CA, but demosaic residue. False edge colors due to the higher acutance between individual sensels which do not have equal colorfilters. It should only happen because these files were created without any color noise reduction.

 
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« Reply #134 on: April 28, 2012, 03:18:18 PM »
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Hi Jan and Oscar,

Why is it that the chromatic abberation on the d800e result is so much worse than with the d800? Huh

Because it is not CA, but demosaic residue. False edge colors due to the higher acutance between individual sensels which do not have equal colorfilters. It should only happen because these files were created without any color noise reduction.

Yes, that's my conclusion as well. This is clearly not caused by classic chromatic aberration due to the lens. If you magnify the edges of the images from both the D800 and the D800E (in PS at highest zoom level), you can see a repeating pattern of red fringing in the D800 image, which is not present in the D800 image. Although the Imatest CA module was not specifically designed to analyze such false-color artifacts, I included the CA charts because I believe they may prove useful in testing the effectiveness of various demosaic algorithms. I also agree that, at least for the slant-edge portions of this chart, the false colors could be easily removed by applying color noise reduction (or CA reduction) methods (especially if applied during raw conversion).

However, I am not yet convinced that any of the tools intended to correct such failures of the Bayer CFA demosaic process (including the new moire removal tools in Lightroom, ACR and Capture NX2) will completely eliminate this issue in all cases.

As a side note, it's often been stated that nature and landscape photographers do not need to worry about artifacts caused by the absence of an effective OLP or AA filter on the sensor. But there are a class of subjects that I have not seen mentioned yet, where it can definitely be an issue. One of my photographic interests is astrophotography, both star trails and guided (on an equatorial mount) fixed images of star fields. Such images are best captured at relatively wide apertures using sharp lenses, under the best possible atmospheric “seeing conditions”.  Due to the inherently small PSF (or Line Spread Function (LSF) in the case of star trails), the star images (Airy-disks) projected on the sensor may not cover enough elements in the Bayer array to allow proper color rendering, resulting in stars or trails with randomly-distributed false colors.

(Hey, why are all the stars in this image red, green or blue, with twice as many green stars as red or blue?! Shocked ---yes, I know that most of the stars won't be rendered pure R, G or B.)

So why not just apply color correction in pp? Part of the appeal of celestial images are the subtle natural colors of the stars and planets. The false-color correction routines I've seen to date also damage these natural color tones This is more than conjecture; I've seen it in my own images and a number of examples online. My current D700 is fairly immune, due to the relatively strong AA filter. But my old D70 (weaker AA filter) did have this issue. One common way to avoid this is to slightly defocus the star images. But this causes loss of the dimmer stars.

Those who like to shoot night scenes involving distant city lights (or any small specular highlight), may also experience this problem.

The high sampling density of the D800/D800E sensor should reduce the occurrence of the above issues. But it is one more thing to be aware of when choosing correct camera.

Kind Regards,
Bob
« Last Edit: April 28, 2012, 03:24:53 PM by RobertCubit » Logged

marcmccalmont
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« Reply #135 on: April 28, 2012, 05:28:27 PM »
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Here is a crude example of what I had in mind for a random target
not sure how to construct it from scratch so it is neat but you can get the idea
I just left the lines that are prime, and the density of the pseudo random target should probably be 2X or 3X
Marc
« Last Edit: April 28, 2012, 07:20:35 PM by marcmccalmont » Logged

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« Reply #136 on: April 28, 2012, 05:48:17 PM »
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Perhaps someone would provide a summary of the acutance difference between the two cameras for those of us not familiar with interpreting imatest charts

Hi Marc,

I'll take a shot at it. I don't want to drive this thread too far OT. But here's my understanding of the acutance results, along with some links for further reading.

For the sake of completeness, acutance is related to Subjective Quality Factor (SQF) and is a measure of perceived sharpness or edge sharpness of an image that includes factors of resolution (MTF) combined with standardized assumptions about human vision and viewing distance. Resolution is not affected by sharpening---acutance is affected by sharpening.

http://en.wikipedia.org/wiki/Acutance

First, be aware that Imatest automatically rescaled the vertical (y-axis) of the charts to match the data from each camera. You need to look at the values next to the left axis (labeled Acutance %) to properly interpret the results. Here you'll see that the acutance plot of D800E is somewhat higher than that of the D800, running from about 80% for a 2.5 cm (1 inch) high print to 47% for a 40 cm (16 inch) high print. The D800 plot runs from about 78% to 39% acutance over the same range of print sizes. So there is a 2% difference in acutance for a 2.5 cm high print and an 8% difference for a 40 cm high print, both in favor of the D800E. The horizontal “Picture Height” (print or display height) chart scale can be extended to include much higher print sizes (not shown), where the improvement in acutance of the D800E over the D800 increases slowly to about 9% difference for a 200 cm (80 inch) high print.

My personal opinion is that these results do not represent a huge difference in acutance between the two cameras. It confirms the previous statements that most of the difference in perceived sharpness (at least for higher contrast edges) between output from the D800 and D800E (in print and display) can be mitigated by proper sharpening. My feeling is that the jury is still out regarding detail that is simultaneously both of high spatial frequency and low contrast, especially as ISO is increased.

Links:

Reading the Imatest SQF and Acutance charts:
http://www.imatest.com/docs/sqf/

A good description of SQF by Bob Atkins:
http://www.bobatkins.com/photography/technical/mtf/mtf4.html

My favorite paper on the value and limitations of MTF testing by Hubert Nasse at Zeiss (2 parts):
http://www.zeiss.de/C12567A8003B8B6F/EmbedTitelIntern/CLN_30_MTF_en/$File/CLN_MTF_Kurven_EN.pdf

http://www.zeiss.de/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/$File/CLN_MTF_Kurven_2_en.pdf

And of course Michael's tutorial from a few years ago:
http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml

The last four links are blessedly free of large complex equations that, upon exposure, have been known to cause some folks to begin sweating, then rapidly degrade into convulsions, followed by invagination of the temples and gray matter dribbling from the ears.

Kind regards,
Bob
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« Reply #137 on: April 28, 2012, 05:58:01 PM »
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Why is it that the chromatic abberation on the d800e result is so much worse than with the d800? Huh
If I understand the replies correctly, this ugly artifact is
- a manifestation of aliasing
- worse without an OLP filter than with
- quite likely to occur in natural scenes when there is a sharp change of luminosity along a line, such as at the edge of a shadow.

Maybe we need to move beyond the ideas that
a) the only aliasing problem is moiré,
b) moiré can only occur with certain made made subjects, and
c) us nature oriented photographers never photograph these sort of man-made subjects, so
d) we have nothing to worry about from a camera with no OLP filter.

It seems to me that all three of (a), (b) and (c) are at least over-simplifications, if not outright wrong, so I am unconvinced of (d). Of course, those who can afford several bodies for use in different situations might find a no-OLP camera to he useful as one part of the kit.
« Last Edit: April 28, 2012, 06:37:18 PM by BJL » Logged
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« Reply #138 on: April 29, 2012, 06:40:42 AM »
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As a user of Foveon based cameras and mirrorless cameras with no or weak OLP filtration, it definitely isn't moire that bothers me in landscapes.  It's stair stepped jaggies that destroy the integrity of the edges of twigs and branches and blades of grass and make thin lines look like they are constructed from lego bricks or laminated from long planks that appear to peeling apart.


If I understand the replies correctly, this ugly artifact is
- a manifestation of aliasing
- worse without an OLP filter than with
- quite likely to occur in natural scenes when there is a sharp change of luminosity along a line, such as at the edge of a shadow.

Maybe we need to move beyond the ideas that
a) the only aliasing problem is moiré,
b) moiré can only occur with certain made made subjects, and
c) us nature oriented photographers never photograph these sort of man-made subjects, so
d) we have nothing to worry about from a camera with no OLP filter.

It seems to me that all three of (a), (b) and (c) are at least over-simplifications, if not outright wrong, so I am unconvinced of (d). Of course, those who can afford several bodies for use in different situations might find a no-OLP camera to he useful as one part of the kit.
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« Reply #139 on: April 29, 2012, 01:32:53 PM »
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Hi Marc,

I usually look at the MTF curves and the MTF at Nyquist. I got the impression that MTF should not exceed around 20% at Nyquist if aliasing is to be avoided.

According to Norman Koren, the author of Imatest, the resolution at which the system transfers 50% MTF is a good measure of the visual acuity of the system. Sorry for the phrasing. I may also check LW/PH at 18% MTF. To be able to restore detail by sharpening, there needs to be some contrast. There are some different criteria, the Raleigh criteria is the most commonly used, but it is intended to separate to images of nearby stars. I sort of decided to use 18% as criteria. My use of the 18% criteria is most intended for study of diffraction, essentially saying that detail can be restored by deconvolution if MTF is higher than 18%. my choice of 18% is quite arbitrary.

Best regards
Erik




Perhaps someone would provide a summary of the acutance difference between the two cameras for those of us not familiar with interpreting imatest charts
Thank
Marc
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