Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: michaelbiondo on July 15, 2017, 06:30:35 pm
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Hello,
I have been shooting architecture with the Pentax 645Z for the past few years. Most of the time I work with the 28-45 zoom and I feel that this camera & lens combo works pretty well for my style of photography. I am very curious about the GFX for several reasons. First, to me, size matters. The Pentax with the 28-45 is a beast of a camera. If the Fuji with the 32-64, or possibly wide angle Nikon or Canon glass was significantly smaller or lighter, I might be tempted to switch for that reason alone. Secondly, for times when I am un-tethered and off-tripod, I really like to see a live histogram in the viewfinder. So having that in the EVF with the Fuji is a big plus. Finally, the versatility of the Fuji, with lenses and tech camera options is also a very attractive feature.
The two questions I have are 1) are the current Fuji GFX users finding the GFX to be reliable? For the past two years of heavy use I have found the Pentax to be bulletproof and I am interested in the Fuji users experience so far. Second question concerns image quality, hard to tell from inner web example and I will only know until I test for myself, but it appears that the Fuji out performs the Pentax when it comes to high ISO performance and sharpness. Could that be true or am I just trying to rationalize a "new toy" purchase. Very interested in what you all think.
Thanks,
MB
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I have heard from other users that the focus of the Fuji is amazingly great and fast, as they complained about the Pentax focus being iffy.
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Hello,
I have been shooting architecture with the Pentax 645Z for the past few years. Most of the time I work with the 28-45 zoom and I feel that this camera & lens combo works pretty well for my style of photography. I am very curious about the GFX for several reasons. First, to me, size matters. The Pentax with the 28-45 is a beast of a camera. If the Fuji with the 32-64, or possibly wide angle Nikon or Canon glass was significantly smaller or lighter, I might be tempted to switch for that reason alone. Secondly, for times when I am un-tethered and off-tripod, I really like to see a live histogram in the viewfinder. So having that in the EVF with the Fuji is a big plus. Finally, the versatility of the Fuji, with lenses and tech camera options is also a very attractive feature.
The two questions I have are 1) are the current Fuji GFX users finding the GFX to be reliable? For the past two years of heavy use I have found the Pentax to be bulletproof and I am interested in the Fuji users experience so far. Second question concerns image quality, hard to tell from inner web example and I will only know until I test for myself, but it appears that the Fuji out performs the Pentax when it comes to high ISO performance and sharpness. Could that be true or am I just trying to rationalize a "new toy" purchase. Very interested in what you all think.
WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.
http://blog.kasson.com/the-last-word/discovering-the-fujifilm-gfx-50s-microlens-size/
My copy of the 32-64 is the sharpest zoom I've used. It has low LoCA, fairly low focus shift, and is not far from parfocality:
http://blog.kasson.com/?s=32-64
It's not quite the equal of the 63/2.8 at the apertures the two lenses have in common, but it's close.
I have had no camera or lens failures. The firmware has been very solid, and Fuji has been quick to correct most of the initial complaints with FW revs. There are tricks to getting reliable manual focus. At some apertures, and some lenses, the AF is not completely accurate, but the errors are small enough that many will not even see them.
It's a camera with a few gotchas, but in general, I am extremely impressed. The lens line is superb, with the exception of the 63, which is merely very good. The quality of the lenses was the biggest surprize for me.
Jim
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WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.
http://blog.kasson.com/the-last-word/discovering-the-fujifilm-gfx-50s-microlens-size/
Jim
I read that blog entry three times expecting it to contain some revelation about the significance of the smaller microlenses that Fuji used in its version of the Sony sensor. I never found it.
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I read that blog entry three times expecting it to contain some revelation about the significance of the smaller microlenses that Fuji used in its version of the Sony sensor. I never found it.
I'm going to assume that there's a question in there. If I'm wrong, ignore the rest of this post.
I'll give you the "See Spot run" version:
Sharper than you'd think by looking at the pixel count.
More aliasing than you'd think by looking at the pixel count.
Jim
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I'm going to assume that there's a question in there. If I'm wrong, ignore the rest of this post.
I'll give you the "See Spot run" version:
Sharper than you'd think by looking at the pixel count.
More aliasing than you'd think by looking at the pixel count.
Jim
I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. I suppose it's possible that it's true, but I certainly wouldn't infer it from that blog entry. Over the years, I have developed a keen appreciation that the difference between people who are really good at what they do and those that are not is the ability to explain complex concepts in an understandable way to those who are not experts in the subject matter. Surely an explanation ought to offer more than a conclusory statement that the "effective fill factor of the GFX 50S is around 76%."
Now, to be clear, I have actually shot the GFX with the GFX zoom and compared the files side by side against the X1D with the 30mm and 45mm lenses. The GFX zoom is impressive in its own right, but once the X1D files were properly sharpened, the files with the X1D lenses were sharper. Not surprising, as I was comparing a zoom with primes. What struck me, however, was that the GFX files seemed as if they were already sharpened right out of the camera, whereas the X1D files were not and could be improved very significantly with good deconvolution sharpening.
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another vote for the GFX, great camera, great system, amazing lenses....
it is still the same sony sensor, so IQ is proven, IMO great up to 800, i try not shoot anything over....AF is pretty amazing for "medium format" but nothing special in comparison to smaller mirrorless....
pretty incredible package all around, price, size, weight, and incredible lenses for very reasonable price (compared to all others including canon and nikon)...
thanks again Jim for doing all the work and showing us in numbers what the eyes see.....
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I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. I suppose it's possible that it's true, but I certainly wouldn't infer it from that blog entry. Over the years, I have developed a keen appreciation that the difference between people who are really good at what they do and those that are not is the ability to explain complex concepts in an understandable way to those who are not experts in the subject matter. Surely an explanation ought to offer more than a conclusory statement that the "effective fill factor of the GFX 50S is around 76%."
Now, to be clear, I have actually shot the GFX with the GFX zoom and compared the files side by side against the X1D with the 30mm and 45mm lenses. The GFX zoom is impressive in its own right, but once the X1D files were properly sharpened, the files with the X1D lenses were sharper. Not surprising, as I was comparing a zoom with primes. What struck me, however, was that the GFX files seemed as if they were already sharpened right out of the camera, whereas the X1D files were not and could be improved very significantly with good deconvolution sharpening.
The blog post says nothing about the sharpness of the Fuji lenses. Indeed, the test results for the curve fitting were done not with a Fuji lens at all, but with an Otus 85/1.4. The blog post is about the extra sharpness over a standard 100% fill-factor sensor caused by the small microlenses in the GFX.
So, I would defy anyone to read that post and "infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. " Just like you.
We are in agreement on the facts.
By the way, I did not write the blog post. It was written by an engineer whose qualifications are summarized on the post as:
"Brandon Dube is a senior optics student at the Institute of Optics, University of Rochester. He works in Dr. Jannick Rolland’s Optical Diagnostics and Testing Lab (ODALAB), as well as the Center for Freeform Optics (CeFO) at the institute, and is also the Director of Metrology at Olaf Optical Testing, which many readers know as Lensrentals, as Olaf is heavily featured on the LR blog. This summer, he has been working at JPL on the cameras for the Mars 2020 rover. Earlier this year, he received the Kevin P. Thompson prize, the highest award given to undergraduate optics students. You can read his resume here (http://www.retrorefractions.com/public/documents/bdube-resume-summer17-01.pdf)."
Jim
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The blog post says nothing about the sharpness of the Fuji lenses. Indeed, the test results for the curve fitting were done not with a Fuji lens at all, but with an Otus 85/1.4. The blog post is about the extra sharpness over a standard 100% fill-factor sensor caused by the small microlenses in the GFX.
So, I would defy anyone to read that post and "infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. " Just like you.
We are in agreement on the facts.
Jim
Well, here's what you said:
"WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses." Sure sounds to me that you were claiming that the smaller microlenses in the Fuji version of the Sony sensor are a special sauce responsible for an exceptional level of sharpness in the output compared to the output from the same sensor in Pentax, Phase and Hasselblad systems. And you cited the blog entry as evidentiary support for that assertion.
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Well, here's what you said:
"WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses." Sure sounds to me that you were claiming that the smaller microlenses in the Fuji version of the Sony sensor are a special sauce responsible for an exceptional level of sharpness in the output compared to the output from the same sensor in Pentax, Phase and Hasselblad systems. And you cited the blog entry as evidentiary support for that assertion.
What you said was: " I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses."
The post says nothing about the sharpness of the Fuji lenses, although they are quite sharp. The post is about the properties of the sensor stack in the GFX, in particular, the microlenses.
I agreed with you that you couldn't draw any conclusions about the Fuji lenses from that post.
I am saying that the exceptional sharpness of images from the GFX sensor -- as measured against the same lenses used on other sensors -- is due to the small micro lenses.
This is not without undesirable side effects, such as increased aliasing.
We saw with the D800/D800E that deconvolution sharpening could compensate to a large degree for an AA filter, at a cost of SNR. So, by extension, it should be possible to sharpen files made with micro lenses that are close to 100% in effective fill factor and make them look very much like the GFX files.
TANSTAAFL.
Jim
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I agreed with you that you couldn't draw any conclusions about the Fuji lenses from that post.
Jim
I would go a step further and say that I couldn't draw any conclusions about anything of real world significance from that post.
What would be instructive to me at least is to take the same Hasselblad lens and mount it on both the GFX and another camera that uses the Sony sensor like the H6D50 or the X1D, turn off all of the baked in sharpening in the raw file and then sharpen them as effectively as possible in Iridient Developer or Photoshop.
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I don't agree on the theory of baked in sharpening. For raw files.
I do agree the Fuji possibly has a different filter array over the sensor with smaller micro lenses. Fuji made a point about the fact the they had Sony make a different array for them.
Just open the GFX files in C1. As C1 has no native support for the files any baked in sharpening would be defeated. Files are plenty sharp. Are the sharper than the X1D I can say as I don't have one. But if they were any sharper I feel the images would appear too sharp.
Images from either camera should be excellent.
Fuji should have stepped up to the plate better on the software support for raw. LR support is lacking and the native Fuji software is worthless. Hasselblad and Phocus is a much better platform. Being able to back door use C1 is very important for me.
Paul Caldwell
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I would go a step further and say that I couldn't draw any conclusions about anything of real world significance from that post.
What would be instructive to me at least is to take the same Hasselblad lens and mount it on both the GFX and another camera that uses the Sony sensor like the H6D50 or the X1D, turn off all of the baked in sharpening in the raw file and then sharpen them as effectively as possible in Iridient Developer or Photoshop.
The post explains why the GFX images with top lenses are so much sharper than you'd think. In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog.
I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter.
In any event, I have sold all my HC lenses, and my Hasselblad bodies.
Jim
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Fuji should have stepped up to the plate better on the software support for raw. LR support is lacking and the native Fuji software is worthless. Hasselblad and Phocus is a much better platform. Being able to back door use C1 is very important for me.
Have you tried Iridient X-Transformer as a front end to Lr? It allows some control that is missing from Lr, like defeating distortion correction profiles.
Jim
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Hi Jim:
I need to look at it again. I tried it early on and did not like the color I was seeing in the dng. But I love the x transformer for x-trans files.
The C1 files to my eyes are a bit cleaner especially past ISO 400, than LR, but I will take another look at the x transformer.
Paul Caldwell
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Hi Jim:
I need to look at it again. I tried it early on and did not like the color I was seeing in the dng. But I love the x transformer for x-trans files.
The C1 files to my eyes are a bit cleaner especially past ISO 400, than LR, but I will take another look at the x transformer.
There are a lot of XT options, so be patient when you first use it.
Jim
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"The post explains why the GFX images with top lenses are so much sharper than you'd think."
Seriously? Explains to whom? An optical engineer?
"In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog."
You mean the ones comparing GFX files with Sony files using the same lens that is non-native to both platforms?
"I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter."
Why not mount the same HC lens on both platforms? That you can do. That would presumably isolate the effect of the magic microlenses on the output, assuming you can turn off any baked in sharpening and then sharpen them the same, or just sharpen them as effectively as possible.
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The post explains why the GFX images with top lenses are so much sharper than you'd think.
Seriously???? Explains to whom??? An optical engineer?
In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog.
You mean the ones comparing GFX files with Sony files using the same lens that is non-native to both platforms?
I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter.
Why not mount the same HC lens on both platforms? That you can do. That would presumably isolate the effect of the magic microlenses on the output, assuming you can turn off any baked in sharpening and then sharpen them the same, or just sharpen them as effectively as possible.
Well, it's clear that it doesn't explain it in a way that works for you, so why don't you just stop trying. There are plenty of other more visual ways of looking at the issue on my web site, particularly the side-by-side comparisons with the a7RII, which has a 100% fill factor. (unfortunately for precise comparisons, the resolution and pitch of the s7RII are different from the GFX).
None of my HC lenses gave the sensor on my GFX an image that was sharp enough for the difference in fill factor to affect the final result. There was so much softness in the lenses that they were the long pole in the tent, not the sensor.
You must have missed this up above: "In any event, I have sold all my HC lenses, and my Hasselblad bodies." So I can't do the test even if I thought it would be useful.
Jim
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WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.
There are people here for whom the link I posted is too detailed and technically challenging. They should ignore this post. For those who are interested in still more details of the search for the secret of the GFX microlenses, here's a link chock full of engineering debate:
https://www.dpreview.com/forums/post/59813210
Short version: Jack Hogan (who is s sometime contributor to LuLa) attacked the problem with a methodology that differs from that employed by Brandon Dube. Jack found the microlenses to be even smaller than Brandon's estimate.
jim
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There are people here for whom the link I posted is too detailed and technically challenging. They should ignore this post. For those who are interested in still more details of the search for the secret of the GFX microlenses, here's a link chock full of engineering debate:
https://www.dpreview.com/forums/post/59813210
Short version: Jack Hogan (who is s sometime contributor to LuLa) attacked the problem with a methodology that differs from that employed by Brandon Dube. Jack found the microlenses to be even smaller than Brandon's estimate.
jim
I can't believe you have so much difficulty understanding the problem with your post. The post only addresses one part of your argument as to why the magical microlenses are so so revolutionary in achieving superior levels of sharpness with the same lens, namely the size of the microlenses. The second part, which I expected to see discussed but never was, is WHY smaller microlenses make a difference in sharpness that cannot be achieved with the "regular" microlenses and highly skilled sharpening techniques. If you had to explain to a group of people who are not engineers why the Fuji microlenses are so significant, would you just trot out Brian Dube to deliver his scientific paper as it was written?
What makes me so skeptical about the magical microlenses thing is that I actually tested the GFX against another camera with the same sensor but with "regular" microlenses. Yes, if you just took GFX files into LR and applied the default sharpening in LR, they looked very sharp. However, they couldn't handle much additional sharpening without becoming crunchy. The X1D files did not look as sharp with the default sharpening in LR, but as soon as the settings were changed to achieve optimal sharpening in LR, the X1D files looked sharper. The same thing was observed by turning off LR sharpening, bringing the files into PS and using the same Focus Magic settings. Moreover, there are some really smart people working at Pentax, Phase and Hasselblad, and none of them reengineered the microlenses. Were they all just asleep at the switch? Or is there a tradeoff in using the magical microlenses that they considered a poor design choice? Soon enough we will know, as the next iteration of the 44x33 medium format Sony sensor will be released next year. We shall see if they all use the same size microlenses.
So, if I understand what you are saying about the HC lenses, the comparison I suggested wouldn't work because the HC lenses suck so bad. The magic microlenses only show their stuff with certain lenses but not others?
I did see your tests with the HC lenses on the GFX. I agree that the leaves on the trees at a distance looked bad. But to be candid, the leaves on the trees in all your tests look really bad to me. Last weekend, I photographed a tree at a long distance with the HC 210 and 300mm lenses and enlarged the files to 300% on the screen and the leaves did not look nearly as bad.
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I can't believe you have so much difficulty understanding the problem with your post. The post only addresses one part of your argument as to why the magical microlenses are so so revolutionary in achieving superior levels of sharpness with the same lens, namely the size of the microlenses. The second part, which I expected to see discussed but never was, is WHY smaller microlenses make a difference in sharpness that cannot be achieved with the "regular" microlenses and highly skilled sharpening techniques. If you had to explain to a group of people who are not engineers why the Fuji microlenses are so significant, would you just trot out Brian Dube to deliver his scientific paper as it was written?
What makes me so skeptical about the magical microlenses thing is that I actually tested the GFX against another camera with the same sensor but with "regular" microlenses. Yes, if you just took GFX files into LR and applied the default sharpening in LR, they looked very sharp. However, they couldn't handle much additional sharpening without becoming crunchy. The X1D files did not look as sharp with the default sharpening in LR, but as soon as the settings were changed to achieve optimal sharpening in LR, the X1D files looked sharper. The same thing was observed by turning off LR sharpening, bringing the files into PS and using the same Focus Magic settings. Moreover, there are some really smart people working at Pentax, Phase and Hasselblad, and none of them reengineered the microlenses. Were they all just asleep at the switch? Or is there a tradeoff in using the magical microlenses that they considered a poor design choice? Soon enough we will know, as the next iteration of the 44x33 medium format Sony sensor will be released next year. We shall see if they all use the same size microlenses.
So, if I understand what you are saying about the HC lenses, the comparison I suggested wouldn't work because the HC lenses suck so bad. The magic microlenses only show their stuff with certain lenses but not others?
I did see your tests with the HC lenses on the GFX. I agree that the leaves on the trees at a distance looked bad. But to be candid, the leaves on the trees in all your tests look really bad to me. Last weekend, I photographed a tree at a long distance with the HC 210 and 300mm lenses and enlarged the files to 300% on the screen and the leaves did not look nearly as bad.
I said above that there is no magic in the small microlenses. They are a win for sharpness, as they are a bit -- but only a bit -- closer to the ideal point sensor. But they lower overall quantum efficiency and increase the probability of aliasing. Indeed, they are in some ways a return to the old days, before microlenses when fill factors were much less than 100%. It's not clear to me that they are a better overall tradeoff than having 100% fill factor. But then again, I am on record as being for AA filters on MF cameras, and that is not a popular position.
I addressed the sharpening question above, using the D800/D800E as examples.
As to why the GFX files get crunchy on sharpening, it may be that they don't need it. It may also be that it's hard to get a deconvolution kernel for a lens with so small an effective fill factor since the GFX is an outlier in that regard. Where did you get your kernel when you did your tests? In general, deconvolution sharpening works well when you have the right kernel and when the SNR is high to start out with, since sharpening adversely affects visible noise.
I did not say the HC lenses suck. On a physically-larger sensor of around 40MP, like the ones for which they were designed, they are pretty good. The sharpness of the file is the product of the MTFs of the sensor and the lens. If the lens is not delivering the sharpness, having a sharp sensor won't help much. If you think of it in terms of blur circles, the two add approximately as the square root of the sum of the squares, so the bigger circle takes over pretty soon. I never owned the 210 and 300 HC lenses.
You will note in all the discussion above, I never said that small microlenses are overall better than large ones, which is an opinion that it seems that you think I have.
Jim
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I said above that there is no magic in the small microlenses. They are a win for sharpness, as they are a bit -- but only a bit -- closer to the ideal point sensor. But they lower overall quantum efficiency and increase the probability of aliasing. Indeed, they are in some ways a return to the old days, before microlenses when fill factors were much less than 100%. It's not clear to me that they are a better overall tradeoff than having 100% fill factor. But then again, I am on record as being for AA filters on MF cameras, and that is not a popular position.
I agree, it's not popular (with traditional MF camera-back users, because they usually have no other choice). But from a Digital Signal Processing (DSP) point of view, a 100% fill-factor and/or a proper Optical Low-Pass Filter (OLPF) does reduce the tendency for generating aliasing artifacts (and problematic demosaicing).
As to why the GFX files get crunchy on sharpening, it may be that they don't need it. It may also be that it's hard to get a deconvolution kernel for a lens with so small an effective fill factor since the GFX is an outlier in that regard.
The latter is a more likely explanation IMHO. It requires a differently shaped deconvolution filter.
If you have the right tools (and I know it was a rhetorical question), then a reduced fill-factor deconvolution filter can be gotten by creating one, e,g, with my online PSF-generator tool here (https://www.bvdwolf.nl/foto/psf/PSF_generator.html). Finding a tool that uses it as input is somewhat harder ...
Cheers,
Bart
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I said above that there is no magic in the small microlenses. They are a win for sharpness, as they are a bit -- but only a bit -- closer to the ideal point sensor. But they lower overall quantum efficiency and increase the probability of aliasing. Indeed, they are in some ways a return to the old days, before microlenses when fill factors were much less than 100%. It's not clear to me that they are a better overall tradeoff than having 100% fill factor. But then again, I am on record as being for AA filters on MF cameras, and that is not a popular position.
These don't address the QQE issue, but here are a couple of visual indications of both the improved above-Nyquist contrast available from smaller microlenses and the increased aliasing. They are simulated images of a 60-spoke raised-sinusoid Siemens Star with fill factor starting at 10% and increasing in steps of 10% to a maximum of 90%, imaged on a sensor with a 5.3 um pitch through a perfectly-focused diffraction-limited lens set at f/2.8. You can also see the effect on false color.
First, with AHD demosaicing:
(http://www.kasson.com/ll/19starFFseq-devAHD.jpg)
and then with bilinear interpolation demosaicing:
(http://www.kasson.com/ll/9starFFseq-devBL.jpg)
If you've done any imaging with Zeiss Siemens Star targets and real cameras, you will probably find the contrast and shot-to-shot stability of the above images better than you can obtain in real life, but if gives an indication.
As to the interaction of small FF microlenses -- and AA filters -- with deconvolution sharpening, I'm still working on how to test that fairly.
Jim
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I said above that there is no magic in the small microlenses. They are a win for sharpness, as they are a bit -- but only a bit -- closer to the ideal point sensor. But they lower overall quantum efficiency and increase the probability of aliasing. Indeed, they are in some ways a return to the old days, before microlenses when fill factors were much less than 100%. It's not clear to me that they are a better overall tradeoff than having 100% fill factor. But then again, I am on record as being for AA filters on MF cameras, and that is not a popular position.
I addressed the sharpening question above, using the D800/D800E as examples.
As to why the GFX files get crunchy on sharpening, it may be that they don't need it. It may also be that it's hard to get a deconvolution kernel for a lens with so small an effective fill factor since the GFX is an outlier in that regard. Where did you get your kernel when you did your tests? In general, deconvolution sharpening works well when you have the right kernel and when the SNR is high to start out with, since sharpening adversely affects visible noise.
I did not say the HC lenses suck. On a physically-larger sensor of around 40MP, like the ones for which they were designed, they are pretty good. The sharpness of the file is the product of the MTFs of the sensor and the lens. If the lens is not delivering the sharpness, having a sharp sensor won't help much. If you think of it in terms of blur circles, the two add approximately as the square root of the sum of the squares, so the bigger circle takes over pretty soon. I never owned the 210 and 300 HC lenses.
You will note in all the discussion above, I never said that small microlenses are overall better than large ones, which is an opinion that it seems that you think I have.
Jim
Jim,
maybe with a small fill factor and a good lens you'll get more aliasing, eg. an mtf that is non zero well past the Shannon limit?
i think there is only so much understanding one can obtain from the easily computed mtf curve. Also, note that if the optics are decent for green, they are going to be more than decent for r,b which have half the limit frequency, and there the aliasing from the sensor is going to hit you in the face, translating into a false-color explosion. Here the values will also be subject to massive numerical aliasing - sampling errors- and then applying a deconvolution will blow up this numerical noise, with artefacts all over the place. I'm just making all of this up as I go along of course, but you must admit it sounds nice and explains why we see fewer sensors with small fill factors and why old MF sensors were called "aliasing machines". I'm sure you have simulation code somewhere which will disprove all my vague intuitions unless by some unlikely accident they happen to be true.
Edmund
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Jim,
maybe with a small fill factor and a good lens you'll get more aliasing, eg. an mtf that is non zero well past the Shannon limit?
i think there is only so much understanding one can obtain from the easily computed mtf curve. Also, note that if the optics are decent for green, they are going to be more than decent for r,b which have half the limit frequency, and there the aliasing from the sensor is going to hit you in the face, translating into a false-color explosion. Here the values will also be subject to massive numerical aliasing - sampling errors- and then applying a deconvolution will blow up this numerical noise, with artefacts all over the place. I'm just making all of this up as I go along of course, but you must admit it sounds nice and explains why we see fewer sensors with small fill factors and why old MF sensors were called "aliasing machines". I'm sure you have simulation code somewhere which will disprove all my vague intuitions unless by some unlikely accident they happen to be true.
You guessed it. I've posted some sim results today that show how diffraction and fill factor interact.
http://blog.kasson.com/the-last-word/siemens-star-diffraction-effects/
I ran experiments today -- not posted yet -- where I ran a natural image (foliage) through the sim at 10%. 60%. 100% fill factors with diffraction-limited lenses from f/2 to f/32. I am amazed at how good the f/2 10% FF image looks, and it must have aliasing up the wazoo.
Jim
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You guessed it. I've posted some sim results today that show how diffraction and fill factor interact.
http://blog.kasson.com/the-last-word/siemens-star-diffraction-effects/
I ran experiments today -- not posted yet -- where I ran a natural image (foliage) through the sim at 10%. 60%. 100% fill factors with diffraction-limited lenses from f/2 to f/32. I am amazed at how good the f/2 10% FF image looks, and it must have aliasing up the wazoo.
Jim
I think false detail is fully acceptable - maybe even desirable - on natural textures, foliage, bark, stone, probably because it preserves the self-similarity measures by which our perceptive processes recognize texture. As defined by another IBM fellow, Benoit Mandelbrot who incidentally was a graduate of, and on a sabbatical year at Ecole Polytechnique when I was blundering my way through my PhD. This actually would be worth looking at at mathematically or at least by means of your simulation.
So, the images from the old 22Mp backs are pleasing because they really do *look* sharp :) - I am willing to bet that if we looked at the sensor MTF here we would see a substantial residual value past the Shannon limit corresponding to the fictitious detail generated by aliasing.
Anyway, my interpretation of your very nice binary stars is that now that fill factor has gone up cameras mostly don't need AA filters, which of course is why many manufacturers proudly advertise their absence as a feature :)
As we both know the computations you have been doing can be found in the remote sensing literature where it has been usual for some time to compute the sensor MTF.
At this point I'll bow out, this forum has seen enough of my pompous self for a few months, and anyway in my old age I've replaced photography with painting.
All the best to you, Jim.
Edmund
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I think false detail is fully acceptable - maybe even desirable - on natural textures, foliage, bark, stone, probably because it preserves the self-similarity measures by which our perceptive processes recognize texture.
Here's a test that bears that out, at least for foliage:
http://blog.kasson.com/the-last-word/simulated-foliage-shots-vs-fill-factor/
In this test, WRT fill factor, there's less there than initially meets the eye.
Jim
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Here's a test that bears that out, at least for foliage:
http://blog.kasson.com/the-last-word/simulated-foliage-shots-vs-fill-factor/
In this test, WRT fill factor, there's less there than initially meets the eye.
Jim
I have an idea for a paper if you're interested, we could rope in Norman Koren from Imatest :)
Your simulator, his MTF software, my bright personality and writing :)
Edmund