Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: nemophoto on February 08, 2015, 03:49:48 pm
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FINALLY, Canon brings out a higher res camera. Only been waiting three or four years. While I'm a pretty diehard 1D user (owned every camera in the series and currently the 1Dx), and have never really taken to the 5D3, this new camera will fit the bill for some of the work I do. (Personally, I don't care if Sony may theoretically have a greater DR, the DR of Canon's cameras is more than sufficient for my needs. Plus, after a day using a friend's Sony A7r, I came away hating the camera and the EVF).
So, my question is (and it might be answered by Nikon users who have used both the D800 and D800E), is there really much of a difference in real resolution? As primarily a fashion shooter, moire has always been a concern and issue. My 1Ds3 showed very little, but I think had a fairly strong AA filter. My 1Dx shows a bit more (especially in blue jeans and certain other types of fabrics), because it has a weaker AA filter to tweak the res upwards. (My own evaluation, nothing I ever read.) At 50MP, the camera will have far more res than anything I've had to date, so it's really a curiosity question.
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So, my question is (and it might be answered by Nikon users who have used both the D800 and D800E), is there really much of a difference in real resolution? As primarily a fashion shooter, moire has always been a concern and issue. My 1Ds3 showed very little, but I think had a fairly strong AA filter. My 1Dx shows a bit more (especially in blue jeans and certain other types of fabrics), because it has a weaker AA filter to tweak the res upwards. (My own evaluation, nothing I ever read.) At 50MP, the camera will have far more res than anything I've had to date, so it's really a curiosity question.
Hi,
I think you'll love the image quality of the 5DS (not the 5DS R if used at wide to medium apertures). Higher resolution will significantly reduce the chance of moiré, especially with a good Raw converter like Capture One (hopefully it will support the 5DS).
I can generate moiré on my 1Ds3 when I use a good lens and perfect focus at optimal apertures (f/4-f5.6 have often the highest resolution until f/7.1 at the narrower end when diffraction take over), but the 5DS should do significantly better.
The denser sampling of the 5DS' 4.14 micron pitch sensels will start to become visually affected by diffraction from f/4.5 and narrower, so around the optimum of the lens. Looks like a perfect match and predictable increase of diffraction smoothing (and aliasing reduction as one goes narrower). Resolution will become totally diffraction limited from f/14 and narrower, virtually (in theory only blue wavelengths could but they contribute little to luminance resolution) no aliasing can be generated due to diffraction cutting resolution at the sensor's Nyquist frequency, not even on the 5DS R version.
Cheers,
Bart
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I would agree with Bart, and many positive things about the 5Ds. One thing I can't agree with is coming to a conclusion about a camera and its system within one day(or even a week if you're not prepared to relearn things). That is just not possible. 10 years ago I was forced into Canon from Nikon, and I was really fighting with the menu system and placement of a number of things, and with time I just had to slow down and accept it being a different approach to acheiving the same thing. As long as you are open minded and don't think that it is either your way(the way you are accustomed to to ), or the highway, you will discover somethings that are a bit more logical, and somethings that are not.
Since these menus do so much they reach over areas they can do well for a certain number of things. As soon as they do something else, they will struggle, and it simply goes both ways. Often this adapts to shooting style and shooting subject/situation you find yourself in more often than not. I say this with very little experience in the Sony menu, yet working with a number of systems, each has its approach, and you have to just stop and read to relearn things that you wish you didn't have to.
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Even though I wish they had 4K for UHD video, they have a pretty nice commercial explaining the internal body/vibration-dampening improvements and overall concept:
http://youtu.be/mzHv-Ej_l8w
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Even though I wish they had 4K for UHD video, they have a pretty nice commercial explaining the internal body/vibration-dampening improvements and overall concept:
I have to like Samsung's approach to 4K, which involves a full readout of the 28MP sensor for each video frame. This kind of bandwidth and throughput is what is necessary, along with fabrication processes that reduce thermal buildup. Supersampling makes a beautiful video frame. The next step involves delivering at least 10 bits and at least 4:2:2 in a raw format. But I don't think we're going to see this kind of throughput from a Canon sensor with this many pixels on it for the time being.
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In fact, I think that there has never been a case for dropping the AA filter. The sole reason is that razor cut pixel peep has a special attraction to us photographers that triggers our want-feelings and it sells well. When it comes to real image quality having an AA filter is always better, unless you shoot at very small apertures (like f/14) where the AA filter won't make any contribution.
You gain extremely little in resolution, say 50 megapixel without AA resolves like a 53 megapixel camera with AA (Bart can probably say something more scientific about that), and do you really need that tiny bit extra in resolution and at the same time increase the risk for various aliasing artifacts?
When an image is published in some form it nearly always involves some scaling up or scaling down, and there can also be image transformations in post-processing like rotations and distortion correction. An aliased input won't do you any good in those cases.
That said the aliasing on the 5Ds R is probably not going to be that bad in practice due to the very high pixel count, so I think most will choose that anyway because people can't resist that pixel peep joy :)
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In fact, I think that there has never been a case for dropping the AA filter. The sole reason is that razor cut pixel peep has a special attraction to us photographers that triggers our want-feelings and it sells well. When it comes to real image quality having an AA filter is always better, unless you shoot at very small apertures (like f/14) where the AA filter won't make any contribution.
You gain extremely little in resolution, say 50 megapixel without AA resolves like a 53 megapixel camera with AA (Bart can probably say something more scientific about that), and do you really need that tiny bit extra in resolution and at the same time increase the risk for various aliasing artifacts?
When an image is published in some form it nearly always involves some scaling up or scaling down, and there can also be image transformations in post-processing like rotations and distortion correction. An aliased input won't do you any good in those cases.
That said the aliasing on the 5Ds R is probably not going to be that bad in practice due to the very high pixel count, so I think most will choose that anyway because people can't resist that pixel peep joy :)
What people seem to forget is that the math describing these things all tend to be approximations with assumptions implied. Once you get in the field where the assumptions may not apply the whole thing can fly out the window. Nothing is ever as cut and dried as the lab measurements predict they will be.
The 5DsR apparently is similar to the D800e in that it has the OLPF and then filters the effect back out. I shoot the D810 and the D7100 and neither has an OLPF in the filter stack. I don't shoot fabrics and other other tightly patterned things that tend to produce moire and have not seen significant artifacts from either, though the D810 is somewhat better than the D7100. I would wait till it gets into the hands of folks before purchasing any new technology.
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What people seem to forget is that the math describing these things all tend to be approximations with assumptions implied.
Hi,
I disagree, when assumptions are based on pure physics.
Things like aliasing are well understood by those versed in in DSP. The only variable is the quality of the optics, which can work like a very mild OLPF if focused well, and make aliasing impossible when defocused or when used with narrow apertures.
I've done an analysis (but not published all details) based on the known specifications (EXIFs also offer info). They show very interesting effects from the combination of sensel pitch and already measured lens performance at various apertures. Based on that, I expect a serious boost in image quality, despite the hardly improved DR. The quality gains are mostly related to an improved MTF.
Things like the separation specifics of the Bayer CFA are unknown, and therefore indeed speculation.
The fact that Canon have specifically addressed things like mirror vibration by reengineering the mechanism from spring to gear based, and vibration timeout setting intervals, looks promising. Practical tests will have to tell how effective it is.
Cheers,
Bart
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Hi,
I am shooting a 6.8 micron MFD on Hasselblad V. I do see a lot of aliasing issues on everyday subjects. It seems that the problem goes away at f/16, while at f/11 it is still very present. This is moiré on sea water surface:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/seawater_a.png)
Best regards
Erik
Hi,
I disagree, when assumptions are based on pure physics.
Things like aliasing are well understood by those versed in in DSP. The only variable is the quality of the optics, which can work like a very mild OLPF if focused well, and make aliasing impossible when defocused or when used with narrow apertures.
I've done an analysis (but not published all details) based on the known specifications (EXIFs also offer info). They show very interesting effects from the combination of sensel pitch and already measured lens performance at various apertures. Based on that, I expect a serious boost in image quality, despite the hardly improved DR. The quality gains are mostly related to an improved MTF.
Things like the separation specifics of the Bayer CFA are unknown, and therefore indeed speculation.
The fact that Canon have specifically addressed things like mirror vibration by reengineering the mechanism from spring to gear based, and vibration timeout setting intervals, looks promising. Practical tests will have to tell how effective it is.
Cheers,
Bart
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Hi,
I disagree, when assumptions are based on pure physics.
Things like aliasing are well understood by those versed in in DSP. The only variable is the quality of the optics, which can work like a very mild OLPF if focused well, and make aliasing impossible when defocused or when used with narrow apertures.
I've done an analysis (but not published all details) based on the known specifications (EXIFs also offer info). They show very interesting effects from the combination of sensel pitch and already measured lens performance at various apertures. Based on that, I expect a serious boost in image quality, despite the hardly improved DR. The quality gains are mostly related to an improved MTF.
Things like the separation specifics of the Bayer CFA are unknown, and therefore indeed speculation.
The fact that Canon have specifically addressed things like mirror vibration by reengineering the mechanism from spring to gear based, and vibration timeout setting intervals, looks promising. Practical tests will have to tell how effective it is.
Cheers,
Bart
We expect to see some gains from the increased MP and other refinements. My point is, that while we can predict some of these, we won't actually know until empirical testing data comes in. And as far as having 50MP goes, that is helpful if you are limited to a 22MP 5DmkII, but not compared to a 50MP A7RII or 50MP DX10 which will in all likelihood also carry DR and ISO performance gains over a 5DmkIII.
As to my actual comment that you quote, I ask: "What is usually the 1st assumption when dealing with lenses in the field of optics?" Hint: One has never been manufactured!
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Thanks for all the different perspectives. Thanks especially to Erik for posting the image from the Hassy. That's exactly the kind of thing I want avoid when I shoot. Back in the day when I shot with the original 1D, I frequently jumped through hoops to try to get rid of moire in garments. Back then, clients were even less forgiving because I was trying to transition them from film! My question was posed as curiosity, but for all practicality, I'd go with the 5Ds. I can't believe that in real world circumstances, the resolution of the 5DsR would be that significant over the "plain vanilla" 5Ds.
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Thanks for all the different perspectives. Thanks especially to Erik for posting the image from the Hassy. That's exactly the kind of thing I want avoid when I shoot. Back in the day when I shot with the original 1D, I frequently jumped through hoops to try to get rid of moire in garments. Back then, clients were even less forgiving because I was trying to transition them from film! My question was posed as curiosity, but for all practicality, I'd go with the 5Ds. I can't believe that in real world circumstances, the resolution of the 5DsR would be that significant over the "plain vanilla" 5Ds.
In any event, I would wait until the results are in from both cameras. But I shoot the D810 (has no OLPF in the stack, not just filtered back out like the D800e or 5DsR) and have not experienced the type of issues Erik's Hassy photo shows with similar subjects. Obviously, Nikon learned something from the D800 pair that allowed them to release a unified body without the OLPF.
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Hi,
Just to say, it is not very common. But it occurs often enough to be a nuisance. Small pixels are beneficial in suppressing moiré.
This article covers a lot of it: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/78-aliasing-and-supersampling-why-small-pixels-are-good
Moiré is not the only colour artefact, see the attached shots:
- 6.8 microns, no OP, processed in Capture 1 V8
- 3.8 microns, OLP, processed in Lightroom 5
- 6.8 microns, no OLP, processed in Lightroom 5
This shot is essentially a test shot, I have noticed that the 6.8 micron camera was aliasing on the subject, and went back to make different test shots. Different cameras, using same focal length from the same shooting position.
I would say that small pixels go a long way to reduce aliasing. The second image is much softer, but contains better detail, check the readability of the text on the signs. The softness is a combination of lens MTF (a decent quality tele zoom at 100 mm at f/8) and probably also an OLP-filter.
Also note that all the thumbnails are aliased, but image #2 doesn't show aliasing at actual pixels. Downscaling is an operation introducing aliasing. Correct downscaling often includes blurring the image slightly before downscaling and applying some sharpening after final size has been reached.
Best regards
Erik
Thanks for all the different perspectives. Thanks especially to Erik for posting the image from the Hassy. That's exactly the kind of thing I want avoid when I shoot. Back in the day when I shot with the original 1D, I frequently jumped through hoops to try to get rid of moire in garments. Back then, clients were even less forgiving because I was trying to transition them from film! My question was posed as curiosity, but for all practicality, I'd go with the 5Ds. I can't believe that in real world circumstances, the resolution of the 5DsR would be that significant over the "plain vanilla" 5Ds.
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Good demonstration Erik. It also shows that Lightroom is not the best at hiding aliasing artifacts, which I've also seen.
Using RawTherapee I've noted that the default demosaicer "Amaze" is great at extracting the most from AA-filtered shots, but renders quite some false colors when there is no AA filter. However when switching to the "DCB" demosaicer you get performance close to Capture One and Phocus in that regard, but there is no demosaicer than can completely solve the problem of a broken signal...
I've attached an enlarged 100% crop of 6um pixels from my H4D-50 shot at f/11, converted by Phocus. This is a section of chaotic tree branches, so you won't find any moire, but false colors are very much present. Most of the magenta stuff is due to aliasing. I think some confuse it with chromatic aberrations, and when it's light desaturated magenta towards blue it's not that apparent. It would be notably worse in a Lightroom conversion.
Today I shoot mostly at f/16 to kill most false colors with diffraction, and I also gain some depth of field. I would probably get slightly better image quality though if I could shoot at f/11 with an AA filter, as the AA filter is more effective at removing aliasing than diffraction is.
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I have to like Samsung's approach to 4K, which involves a full readout of the 28MP sensor for each video frame. This kind of bandwidth and throughput is what is necessary, along with fabrication processes that reduce thermal buildup. Supersampling makes a beautiful video frame. The next step involves delivering at least 10 bits and at least 4:2:2 in a raw format. But I don't think we're going to see this kind of throughput from a Canon sensor with this many pixels on it for the time being.
I agree. Unfortunately.
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Thank Erik. Interesting sample of moire, etc. Why didn't you create the same size sample of the smaller micron sensor as an example compared to the others?
For those pining away for 4K video (and I'm not one of them), this isn't the camera to feature it. There was a great interview on DPReview with Chuck Westfell from Canon. In it he was very clear that, essentially, the "logistics" (my word) of pushing that much data through a 50MP is not practical. I think, for the time being, those truly interested in video, would be better served using the 5D3 or even the 7D2. Or of course, pick up the 1Dc. I think Canon figured they should through video in with the camera, but probably felt this was a camera to serve still shooters (like me) who have clambered for higher res first, and the occasional videographer second.
I'm not quite sure why everyone is trashing the camera before any true samples have been test, whether or not is uses the 7D2 chip fabrication or not. If you don't like the results, switch to Sony or Nikon. For me, I believe as much as I'd prefer a 1D-series body, it will do well for my needs. Until Sony actually introduces something, it's still vaporware. For a few short minutes, here and there, I've contemplated jumping ship, but I'm honestly too heavily invested in Canon gear at this point. Had Sony put more effort into something like the A99, that would have been far more appealing. I personally hate the A7 series cameras. Using one for a day made me feel that way. I just found it annoying to use. But that's me. I'm a traditionalist and prefer and optical viewfinder. Mirrorless cameras are fine if I want to plunk around, take shots while hiking, etc. But give me the two ton brick for my commercial work. I know it won't fail me. Just my 2-cents.
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Hi,
I didn't have the time...
Here is a comparison, both samples from processed in Lightroom.
BTW, one reason not to downscale the 3.8 micron image is that original image actually shows the true resolution of that image.
Best regards
Erik
Thank Erik. Interesting sample of moire, etc. Why didn't you create the same size sample of the smaller micron sensor as an example compared to the others?
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Erik, very interesting to see. Thanks for sharing! The comments made by some that smaller photosites are less likely to cause moire might be the reason the original 1D had such issues. I believe the photosites were something 8.3 microns.
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Maybe the science says otherwise, and some tests use particular lens selects that show issues of moire without AA filters, but with the select gear I have and use....Importantly with subjects I work with, I have to say that the sensors I use without an AA create a noticeably sharper, more 3D raw file vs those with an AA.
The difference is something I see, and I cannot see post sharpening be the better alternate, nor be equal to getting the original lines (or as good) in the image.
Maybe its the macro subjects, but the difference is clear in my tests(DSLR, full, crop, DSLR without AA, MFdb without AA).
Having said this I have respect for a number of posters here, and i'd like to see how I can better understand this.
There are a couple users here that have "scientifically" tested a few things, and I'd like to put theirs and my findings to see whats going on....Before I no longer have the gear/chance to do so. Since in macro work the pixel peeping is not only a self driven desire, as the work has to be perfect and demands it. Editing has to be clean with a solid chunky file.
I'm open to testing, if you are. I can think of Erik and Bart.... and there are a few others not coming to mind at the moment...but we can setup some parameters to work under/?
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Hi,
The AA-filter reduces MTF, so that is expected.
The Canon 5Ds has higher resolution (in lp/mm) than any full format or MFD camera, so it may be a good candidate to use without AA-filter, although theoretical studies indicate that pixel pitches around 2.5 microns may be needed for correct rendition with very high quality lenses at near optimal apertures.
OLP filtered or not, the OLP filter is always designed for the pixel size, so the effect of the OLP filter is reduced withe decreasing pixel size.
What apertures do you use? On my P45+ at 6.8 microns I see a lot of issues when shooting at f/11, they go away at f/16. From that I guess that the Canon 5Ds would be aliasing free at f/9 or so.
Best regards
Ertik
Maybe the science says otherwise, and some tests use particular lens selects that show issues of moire without AA filters, but with the select gear I have and use....Importantly with subjects I work with, I have to say that the sensors I use without an AA create a noticeably sharper, more 3D raw file vs those with an AA.
The difference is something I see, and I cannot see post sharpening be the better alternate, nor be equal to getting the original lines (or as good) in the image.
Maybe its the macro subjects, but the difference is clear in my tests(DSLR, full, crop, DSLR without AA, MFdb without AA).
Having said this I have respect for a number of posters here, and i'd like to see how I can better understand this.
There are a couple users here that have "scientifically" tested a few things, and I'd like to put theirs and my findings to see whats going on....Before I no longer have the gear/chance to do so. Since in macro work the pixel peeping is not only a self driven desire, as the work has to be perfect and demands it. Editing has to be clean with a solid chunky file.
I'm open to testing, if you are. I can think of Erik and Bart.... and there are a few others not coming to mind at the moment...but we can setup some parameters to work under/?
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For those pining away for 4K video (and I'm not one of them), this isn't the camera to feature it.
I agree. If 4k video is important to you, looking at the highest sensel count stills-focused camera is a strange thing to do. Why would you want the manufacturer to go to the expense of reading out and processing >50 million sensels, only to downsample to 2000x4000? I mean, in due time this will perhaps be a standard feature of cellphones costing next to nothing, but right now this sensel count probably adds to the cost (and detracts from the flexibility) of a given product.
The Sony A7(s), rumored Canon 5Dmk4 and others in that class are probably better targeted at delivering good quality video (including 4k).
-h
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Hi,
The AA-filter reduces MTF, so that is expected.
The Canon 5Ds has higher resolution (in lp/mm) than any full format or MFD camera, so it may be a good candidate to use without AA-filter, although theoretical studies indicate that pixel pitches around 2.5 microns may be needed for correct rendition with very high quality lenses at near optimal apertures.
It would be interesting to take the theoretical/optimal findings to a more practical level. I am sure that it would also cause some dissent.
I believe that applying some degree of AA filtering can only reduce the magnitude of the MTF.
1. What kind of deconvolution is needed to make a given D800 image match a D800E image of the same scene, given optimal known technique, algorithms and parameter settings? How is the noise vs sharpness trade-off at high frequencies (perfect sharpness match might mean objectionable levels of high-frequency noise/artifacts). I believe that Bart has contributed on optimal gaussian deconvolution parameters, but how do you factor in the SNR at those frequencies in a visually enlightning way?
2. How close can a given image be matched in e.g. Lightroom for a D800/D800E comparision (assuming that commercial software is not necessarily optimal)
3. At what (if any) smaller apertures does the AA filter reduce sharpness by some non-trivial amount while diffraction ensure trivial amounts of aliasing even without the AA filter (is there a case for removing the AA filter for those who regularly want deep DOF and good detail, but may still not like aliasing)?
4. For a given AA filter blur (e.g. 0.7x sensel pitch horizontal and vertical comb filter), how large camera vibrations would be needed to obtain similar*) blur? For 50MP and e.g. 200mm lens, I have a gut-feeling that you have to bolt your camera really well to the ground for this to matter much, even if lens and focusing and aperture is ideal.
*)Camera movements and comb filters cause different blurring, but say that the camera is kept at 1/4 of the exposure at 2x2 different positions, corresponding to the "taps" of the AA comb filter.
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Hi,
The problem is that we don't have very much of comparable equipment. There are some Nikon users who own both the D800/D800E.
- What I can see is that I have a lot aliasing related problems on the P45+, 6.8 Microns no AA filter.
- There is some aliasing on my Sony Alpha 99 with 6 micron pixels and AA filter.
- With my Sony Alpha 77 I don't see aliasing problems.
But, I would also say that I don't feel the AA-filter is intended to eliminate aliasing, just to reduce colour aliasing and demosaic errors. The best way to reduce aliasing is to increase sampling frequency, that is reduce pixel size. At one point the AA filter will not be needed.
I don't think 4 microns are small enough, as Canon would not offer the Canon 5Ds with and without AA-filtering if AA-filtering was not needed in certain cases.
Regarding camera shake, it seems to be little problem with EFCS (Electronic First Curtain Shutter).
Best regards
Erik
It would be interesting to take the theoretical/optimal findings to a more practical level. I am sure that it would also cause some dissent.
I believe that applying some degree of AA filtering can only reduce the magnitude of the MTF.
1. What kind of deconvolution is needed to make a given D800 image match a D800E image of the same scene, given optimal known technique, algorithms and parameter settings? How is the noise vs sharpness trade-off at high frequencies (perfect sharpness match might mean objectionable levels of high-frequency noise/artifacts). I believe that Bart has contributed on optimal gaussian deconvolution parameters, but how do you factor in the SNR at those frequencies in a visually enlightning way?
2. How close can a given image be matched in e.g. Lightroom for a D800/D800E comparision (assuming that commercial software is not necessarily optimal)
3. At what (if any) smaller apertures does the AA filter reduce sharpness by some non-trivial amount while diffraction ensure trivial amounts of aliasing even without the AA filter (is there a case for removing the AA filter for those who regularly want deep DOF and good detail, but may still not like aliasing)?
4. For a given AA filter blur (e.g. 0.7x sensel pitch horizontal and vertical comb filter), how large camera vibrations would be needed to obtain similar*) blur? For 50MP and e.g. 200mm lens, I have a gut-feeling that you have to bolt your camera really well to the ground for this to matter much, even if lens and focusing and aperture is ideal.
*)Camera movements and comb filters cause different blurring, but say that the camera is kept at 1/4 of the exposure at 2x2 different positions, corresponding to the "taps" of the AA comb filter.
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I don't think 4 microns are small enough, as Canon would not offer the Canon 5Ds with and without AA-filtering if AA-filtering was not needed in certain cases.
Nikon would seem to think differently, as they are offering their D810 (4.88 micron?) only sans AA filtering?
-h
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Yes,
That may be the case.
On the other hand, the samples on Imaging resource show aliasing that is not present on the D800, check attached image. D810 on the left, D800E center and D800 right.
Best regards
Erik
Nikon would seem to think differently, as they are offering their D810 (4.88 micron?) only sans AA filtering?
-h
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With the DSLR I am shooting "around F16". I actually have not taken that Leica Macro el100 lens out in some time. After I did my tests I came to the conclusion and put a few things away. So I'd have to retest.
I can test it with the Canon 180L Macro also, but I think at the time I found the Leica to very close or sharper/(contrast perhaps?).
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From that image: the 2 on the right can be better focused. They look like a small crop of a much larger image.
There is going to be some situations that moire shows up.
Maybe you are saying that after the size of pixel is less than 3 there is ZERO chance of moire/In relation to lens ? I think it may drop further, but not zero.
Either way, the image is printed with line screen, so it picked up that pattern. Its not that the artifacts were created from thin air. Most offset printing is done between 70-200line screen(150 average for color).
Oddly enough, years back I read an article that at some point sensors technology would slowly go to a single pixel with very high resolution. I think this would eliminate the problem you show :-)
This type of artifact on flat surface is very easy to fix, and I would rather have this problem to fix once in a blue moon vs not getting the optimal sharpness I can to start with.
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Hi,
F/16 would eliminate aliasing on pretty large pixel pitches. Personally I shoot mostly f/8 on DSLRs and f/11 on the P45+.
This is P45+ at f/8, 6.8 micron pixels:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/NYSINYD/20140104-CF044491.jpg)
And this is P45+ at f/16:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/NYSINYD/20140104-CF044493.jpg)
An SLT 77 at f/8 with 3.8 micron pixels:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/Test3/PNGs/20140104-_DSC5732_sharpened_v3_cropped.png)
The same image as above, properly downscaled:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/Test3/PNGs/20140104-_DSC5732_sharpened_v3_cropped_scaled.png)
What this shows is that:
- f/16 on P45+ pretty much eliminates aliasing.
- A small pixel camera like 3.8 micron pixel avoids aliasing mostly at f/8
- The small pixel camera actually resolves more details
- The image downscaled from the small pixel camera has better detail
All images from this article: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/78-aliasing-and-supersampling-why-small-pixels-are-good
Best regards
Erik
With the DSLR I am shooting "around F16". I actually have not taken that Leica Macro el100 lens out in some time. After I did my tests I came to the conclusion and put a few things away. So I'd have to retest.
I can test it with the Canon 180L Macro also, but I think at the time I found the Leica to very close or sharper/(contrast perhaps?).
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The small pixel 77 camera resolves more details vs the P45+ is what you're saying.
How is it that the P45+ file is smaller than the 77?
Can you clarify your statement about the 77 showing more detail vs the P45 at F16? Is F16 the optimal sharpness for that lens?
I don't know why, but you dollor bill images for the P45 look low contrast.
Downsampling has an advantage. I would not consider that apples to apples.
Just this small difference you have is enough to fill in small detail areas in an image.
The top one is the 77 downsampled. You can see clearly the difference in file processing results.
I took measurements off the area just below the D and the 77 file has a lower blackpoint.
Your conclusions at the end is something I can agree with, No, moire does not happen often. I have been shooting with NON OLP filter sensors for close to 10 years and I think it happened once or twice on fabric. So for me the AA should only be an OPTION, as I would likely never use it. I think Canon should have had the courage to have zero AA filter, not a just a weak one.
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Hi,
The crops are actual pixels. The Alpha 77 has smaller pixels then the P45+, so the image is larger. Keep in mind that this is a pixel size demo, and not an MFDB vs APS-C comparison. Both images are shot with lenses of same focal length, at the same distance. Described in the article I was referring to.
The optimal aperture on the Hasselblad lens is probably f/5.6 - f/8, the image below is at f/8:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/NYSINYD/20140104-CF044491.jpg)
While the one below is at f/16, what is shown that artefacts are almost eliminated but at the cost of loss sharpness:
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/NYSINYD/20140104-CF044493.jpg)
If you check the small pixel image, it contains much better detail than any of the above images. It was also shot at f/8.
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/Test3/PNGs/20140104-_DSC5732_sharpened_v3_cropped_scaled.png)
Contrast differences probably come from processing variations, but stopping down to f/16 reduces global contrast.
Also, keep in mind that no well made lens for small or medium formats ever performed best at f/16. Large format lenses is a different case, as they are never used at large apertures. Any decent small format lens performs best between f/4 and f/8. This applies rom simple Nikkors to Coastal Optics and Otuses.
Left column on this page page demonstrates the effect of diffraction at different apertures on 4.8 micron pixel sensor (36 MP on full frame)
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/49-dof-in-digital-pictures?start=1
The lesson from this is that smaller pixels actually give more and better detail without generating fake detail, and can be used near optimal apertures without risking moiré.
This image shows that colour artefacts can occur on rippled water (P45+, Distagon 40/4 at f/11):
(http://echophoto.dnsalias.net/ekr/Articles/Aliasing2/seawater_a.png)
Best regards
Erik
The small pixel 77 camera resolves more details vs the P45+ is what you're saying.
How is it that the P45+ file is smaller than the 77?
Can you clarify your statement about the 77 showing more detail vs the P45 at F16? Is F16 the optimal sharpness for that lens?
I don't know why, but you dollor bill images for the P45 look low contrast.
Downsampling has an advantage. I would not consider that apples to apples.
Just this small difference you have is enough to fill in small detail areas in an image.
The top one is the 77 downsampled. You can see clearly the difference in file processing results.
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Maybe the science says otherwise, and some tests use particular lens selects that show issues of moire without AA filters, but with the select gear I have and use....Importantly with subjects I work with, I have to say that the sensors I use without an AA create a noticeably sharper, more 3D raw file vs those with an AA.
The difference is something I see, and I cannot see post sharpening be the better alternate, nor be equal to getting the original lines (or as good) in the image.
Maybe its the macro subjects, but the difference is clear in my tests(DSLR, full, crop, DSLR without AA, MFdb without AA).
Hi Phil,
I'm also involved (but not exclusively) in Photomacrography, and can tell from experience that most folks shoot with apertures that are too narrow for quality, just to get some more Depth of Field. One then stacks the effects of diffraction on top of anti-aliasing filters, which is often too much. In such a case, it can help to avoid the use of an OLPF, although in my experience it can then rear the ugly head of aliasing in e.g. specular highlights.
Having said this I have respect for a number of posters here, and i'd like to see how I can better understand this.
There are a couple users here that have "scientifically" tested a few things, and I'd like to put theirs and my findings to see whats going on....Before I no longer have the gear/chance to do so. Since in macro work the pixel peeping is not only a self driven desire, as the work has to be perfect and demands it. Editing has to be clean with a solid chunky file.
I'm open to testing, if you are. I can think of Erik and Bart.... and there are a few others not coming to mind at the moment...but we can setup some parameters to work under/?
Not sure what it exactly is what you want to test, but maybe the attached (but not a yes/no OLPF comparison) image I made for a different thread on TS lenses can still help a bit. It also shows the incremental benefit of using dedicated lenses. The recent edition of a € 5 note has an incredible amount of detail of varying contrast, and the (recent updated model) EF 100mm f/2.8L Macro offers an incredible amount of detail on a camera with OLPF, but one needs to use a relatively wide aperture (I used f/4.5) to avoid diffraction. That also means that I (need to) do a lot of focus stacking on stationary subjects to regain DOF. The 100% zoom crop represents an approx. 6.5x6.5 mm area in the original subject, shot at approx. a 1:2.4 ratio. I can't show a larger piece due to copyright restrictions, and Photoshop probably refuses to open complete reproductions of banknotes anyway .
My earlier tests on the difference between a Nikon D800 versus a D800E showed only a small, approx. 1%, difference in limiting resolution. I did see many more aliasing issues on shots of my cruel/merciless Star resolution test target from the OLPF-less camera model.
Cheers,
Bart
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It would be interesting to take the theoretical/optimal findings to a more practical level. I am sure that it would also cause some dissent.
I believe that applying some degree of AA filtering can only reduce the magnitude of the MTF.
1. What kind of deconvolution is needed to make a given D800 image match a D800E image of the same scene, given optimal known technique, algorithms and parameter settings? How is the noise vs sharpness trade-off at high frequencies (perfect sharpness match might mean objectionable levels of high-frequency noise/artifacts). I believe that Bart has contributed on optimal gaussian deconvolution parameters, but how do you factor in the SNR at those frequencies in a visually enlightning way?
Hi,
Not exactly sure what you mean with the SNR remark, but one obviously needs to use a deconvolution method that favors detail over noise, for an effective increase of the SNR. The regularized Richardson Lucy algorithm is still a very good algotithm, although for low noise images the regularized Van Cittert algorithm can also do wonders. Specific versions of deconvolvers are useful for spatially variant deconvolution across the image, e.g where the corners need very different parameters compared to the center of the image. Deconvolution can also be only applied on masked regions with a certain level of minimum detail, and thus spare smooth gradients from amplified noise.
2. How close can a given image be matched in e.g. Lightroom for a D800/D800E comparision (assuming that commercial software is not necessarily optimal)
Depending on the gap to close, the visual impression of contrast roll off towards higher spatial frequencies can be reduced by deconvolution. So then in output, it will be extremely hard to see any difference, unless the images are magnified a lot. Then the OLP filtered images will has marginally less absolute resolution, but it also depends on subject contrast. The magnification will also increase the visibility of aliasing artifacts, so it's a complex issue to answer, TANSTAAFL.
3. At what (if any) smaller apertures does the AA filter reduce sharpness by some non-trivial amount while diffraction ensure trivial amounts of aliasing even without the AA filter (is there a case for removing the AA filter for those who regularly want deep DOF and good detail, but may still not like aliasing)?
The effects of diffraction are not abrupt, so they will gradually increase as one stops down from wide open. It then becomes the interaction of the Lens MTF (limited by residual aberrations and defocus) and Diffraction that determines the effect on modulation. This is called the Optical Transfer Function (OTF), and its formula (which requires integation) is given e.g. by David Jacobson's excellent FAQ/tutorial (http://photo.net/learn/optics/lensTutorial#part4).
In my experience, the Diffraction effects start to just become visually apparent when the diffraction pattern diameter becomes larger than 1.5x the sensel pitch. Others use a more relaxed criterion of 2x sensel pitch, but then I'm maybe more sensitive to seeing the degradation. From there on the diffraction will increase with the use of narrower apertures, until it completely destroys any modulation, at a spatial frequency of Cycles/mm = 1/(wavelength x Aperture), where wavelength is expressed in the same units as the spatial frequency, i.e. millimetres (e.g. 0.000555 for green filtered sensels, as explained here (http://spie.org/x34304.xml)).
Slightly before diffraction alone reduces modulation/resolution to zero, the modulation will already be so low that only the highest contrast subject features stand a chance of being resolved, assuming the use of a perfect lens an perfectly circular apertures. More modest subject contrast will already lose enough system modulation to be unresolvable at lower spatial frequencies.
4. For a given AA filter blur (e.g. 0.7x sensel pitch horizontal and vertical comb filter), how large camera vibrations would be needed to obtain similar*) blur? For 50MP and e.g. 200mm lens, I have a gut-feeling that you have to bolt your camera really well to the ground for this to matter much, even if lens and focusing and aperture is ideal.
Obviously camera handling/technique will play a role, but it's hard to quantify, because so many other factors also play a rol. Defocus is one of the major ones, and there is only a very narrow range with truly perfect focus, the rest is just 'acceptable' (from a COC point of view, which is output viewing conditions related).
Cheers,
Bart
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I think Canon should have had the courage to have zero AA filter, not a just a weak one.
Hi Phil,
It's not a matter of courage. Modern lens designs have, as part of their optical design, the presence of a filterstack (IR filter, OLPF+Quarterwave plate+OLPF, sensor coverglass) included in the optimization calculations. By completely leaving out these optical elements from the optical path, the lens will now start to exhibit lots of deterioration from new residual lens aberrations. So to avoid having to use different lenses for different cameras, they chose to employ a OLP canceling method, just like Nikon did when they brought out the D800/D800E combo.
Cheers,
Bart
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Not exactly sure what you mean with the SNR remark, but one obviously needs to use a deconvolution method that favors detail over noise, for an effective increase of the SNR. The regularized Richardson Lucy algorithm is still a very good algotithm, although for low noise images the regularized Van Cittert algorithm can also do wonders.
My point was that if the AA-less camera produces what a given user wants (for a given scene), then the AA-filtered camera will have to be processed by deconvolution/sharpening in order to approximate that image.
If the SNR in spatial frequencies of interest is very low, then any algorithm to lift out the signal by a large amount is going to have a hard time. Thus, the difference between the 5Ds vs the 5DsR is not simply a matter of the linear spatial frequency response (difference), but also the expected SNR for a given scene/exposure in the significantly affected frequencies. If you can have 20dB SNR, then I assume that differences in sharpness can be reduced a lot. If you have 3 dB SNR, it might be hard to increase signal without excessive artifacts.
-h
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While I do think it's a good idea with OLPF and that sharpening can compenaste for added blur there is indeed a challenge of introducing noise as the OLPF-filtered image needs higher levels of sharpening. I mostly use simple USM sharpening (boosted with thresholds tricks), so I guess you can improve it with the more advanced sharpening packages. However I don't find a mild grain be as problematic as various aliasing artifacts so for my taste the increased noise is not much of a problem.
In the past I was thinking that diffraction could be a good replacement for an OLPF in landscape photography when you shoot with small apertures. I don't think that as much any longer. Diffraction blur is a soft onset with a large radius which means it's quite ineffective at killing aliasing, ie you need high levels of diffraction before aliasing disappears, and then you can have issues with global contrast and bleed around high contrast details. OLPF only blurs to the neighbor pixel as far as I know and to a higher extent so it's quite effective at killing aliasing while not lowering global contrast or bleeding too much.
With my 50MP MFD system I've found f/16 to be a suitable tradeoff between diffraction blur and aliasing removal, which corresponds to f/11 on the 5DS R. You still have aliasing left but a lot less than with one stop larger aperture, and it's still easy to sharpen without too much noise or artifact increase.
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To put it in perspective, I get more moire with my 12MP X100 than I ever have with my D800E. The issue is so small Nikon did away with the AA filter on the D810 (and the D7100) and this camera has even more resolution.
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My point was that if the AA-less camera produces what a given user wants (for a given scene), then the AA-filtered camera will have to be processed by deconvolution/sharpening in order to approximate that image.
Hi,
I think there may be a bit of a misconception in that assumption. The fact is that all images require (deconvolution) Capture sharpening, it's just that aliasing prohibits us from doing what is required on non-OLP filtered images (because that would exacerbate the aliasing artifacts). All lenses, even the OTUS types, have some residual aberrations and some diffraction in the mix. The filter stack and sampling aperture will also introduce some blur.
If the SNR in spatial frequencies of interest is very low, then any algorithm to lift out the signal by a large amount is going to have a hard time.
Yes, but you may be surprised at what is possible, assuming the original was properly pre-filtered. I'm not saying that Bayer-CFA images are properly pre-filtered or bandwidth limited, they aren't. But they do offer a better chance of surviving when they are low-pass filtered to some degree (however little or insufficient).
Cheers,
Bart
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While I do think it's a good idea with OLPF and that sharpening can compenaste for added blur there is indeed a challenge of introducing noise as the OLPF-filtered image needs higher levels of sharpening. I mostly use simple USM sharpening (boosted with thresholds tricks), so I guess you can improve it with the more advanced sharpening packages. However I don't find a mild grain be as problematic as various aliasing artifacts so for my taste the increased noise is not much of a problem.
In the past I was thinking that diffraction could be a good replacement for an OLPF in landscape photography when you shoot with small apertures. I don't think that as much any longer. Diffraction blur is a soft onset with a large radius which means it's quite ineffective at killing aliasing, ie you need high levels of diffraction before aliasing disappears, and then you can have issues with global contrast and bleed around high contrast details. OLPF only blurs to the neighbor pixel as far as I know and to a higher extent so it's quite effective at killing aliasing while not lowering global contrast or bleeding too much.
Hi,
Yes, diffraction is a rather poor substitute for a dedicated OLPF. The only benefit is that it blurs Red more than Green, but that won't matter that much in a luminance dominated demosaicing scheme.
Cheers,
Bart
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Erik, thanks for posting those moire images of the beer label. Not sure how exactly the 5Ds and R would compare, because of everyone stating the smaller pixel photosites means fewer problems. But the label issue would definately be a no-go for me as a fashion shooter. I still have to deal with it enough with my 1Dx. Interestingly, my old 1Ds3 had far fewer issues than my 1Dx. I've always thought Canon weakened the AA filter on the 1Dx to lightly boost the res. Conversely, I don't really see much of a res gain on the samples of the Nikon 810 and 800E versus the 800. To my eye, what you really see is a slight contrast difference. I slight haze in a way. Easily correctable in post. One thing I've often said about digital versus film -- it's almost too sharp. I do far more retouching now than I did with scanned film! Especially with beauty.
To me, the biggest difference will be with in-store posters I shoot for one client. They are about 8 feet tall. Based on the files they request, (about 1/4 size at 400 ppi) I have to res up the final file anywhere from about 140% to 180%. The native 5Ds file would yield a file that would essentially be 100% most of the time. Hmm, I think I may need to boost my RAM from 32GB to 64GB! If I guess correctly, that will be a 500GB 16-bit file right out the gate, without ANY layers.
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Interesting stuff, and funny enough we have covered most of this a few times:-)
If I want 1 tool doing most all tricks, and I know from my experience that it isn't the best way to "skin the cat".
Anyway, I have read for a few years, and seen it myself, but was never sure if that was the reason for the way the colors and lumes are laid out, but CCD vs CMOS I thought had something to do with SNR for clearer separation contrast?
(I hope I don't steer you into that topic entirely)
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Hi,
I discovered this example when checking out Imaging Resource's Pentax 645D test. I have also observed a similar patten on the Sony A7r. Now, this kind of stuff doesn't show up that often, as it requires fine structures in the image and good utilisation of the optical system.
Once Imaging resource tests the Canon 5DR, this bottle will be a good test if the OLP filter is needed or not.
Best regards
Erik
Erik, thanks for posting those moire images of the beer label. Not sure how exactly the 5Ds and R would compare, because of everyone stating the smaller pixel photosites means fewer problems. But the label issue would definately be a no-go for me as a fashion shooter. I still have to deal with it enough with my 1Dx. Interestingly, my old 1Ds3 had far fewer issues than my 1Dx. I've always thought Canon weakened the AA filter on the 1Dx to lightly boost the res. Conversely, I don't really see much of a res gain on the samples of the Nikon 810 and 800E versus the 800. To my eye, what you really see is a slight contrast difference. I slight haze in a way. Easily correctable in post. One thing I've often said about digital versus film -- it's almost too sharp. I do far more retouching now than I did with scanned film! Especially with beauty.
To me, the biggest difference will be with in-store posters I shoot for one client. They are about 8 feet tall. Based on the files they request, (about 1/4 size at 400 ppi) I have to res up the final file anywhere from about 140% to 180%. The native 5Ds file would yield a file that would essentially be 100% most of the time. Hmm, I think I may need to boost my RAM from 32GB to 64GB! If I guess correctly, that will be a 500GB 16-bit file right out the gate, without ANY layers.
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...
So to avoid having to use different lenses for different cameras, they chose to employ a OLP canceling method, just like Nikon did when they brought out the D800/D800E combo.
Cheers,
Bart
I'm puzzled by this because the same lenses are used on the Nikon D810 (no AA filter) and the D800 (with AA filter). I thought the reason for "negating" instead of removing the AA filter was to have the ability to offer a camera without moire artifacts to those who need it, plus a higher resolution camera for landscape and other uses, that are identical except for the filter stack. That makes manufacturing two models instead of one relatively easy. If the AA filter was simply removed in one model instead of "negated", the focusing system design would differ, possibly including physical location of the focusing screen, sensor, and AF components. That means the "with AA" and "without AA" cameras would be completely different, manufacturing costs would be higher, and development time longer. What am I missing?
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If the AA filter was simply removed in one model instead of "negated", the focusing system design would differ, possibly including physical location of the focusing screen, sensor, and AF components.
I think that's it: it fits with both Nikon and Canon using the the added expense of two birefringent layers in their pairs of "OLPF/non-OLPF" models, while no camera maker uses this approach in any other purely non-OLPF camera. If lens designs required this approach, that would apply to all the other camera models with no OLPF, but none of the others do it this way.
The main point I see is that the sensor would need to be positioned differently for the two "non-identical twins", potential requiring a variety of changes in the mechanical design and even two manufacturing production lines in places where the twins can share one.
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If the AA filter was simply removed in one model instead of "negated", the focusing system design would differ, possibly including physical location of the focusing screen, sensor, and AF components. That means the "with AA" and "without AA" cameras would be completely different, manufacturing costs would be higher, and development time longer. What am I missing?
Hi Dean,
The filterstack is part of the optical design of modern lenses. See here (http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses) and here (http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter). Roger Cicala found out the hard way, that lens testing in isolation will give poor MTF information, because the filterstack is not in the optical path.
Cheers,
Bart
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Hi,
The optical package can be replaced by glass of equivalent thickness.
My guess is that the rear lithium niobate plate is normally bonded to the sensor. What Canon/Nikon probably have done was:
- Flip the first lithium niobate plate
- Remove the depolarising layer between the tow plates
With the D810 Nikon decided that the OLP filter was not necessary, so they simply use simple optical glass to replace OLP filtering assembly. Saves a lot of expenditure.
Best regards
Erik
Hi Dean,
The filterstack is part of the optical design of modern lenses. See here (http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses) and here (http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter). Roger Cicala found out the hard way, that lens testing in isolation will give poor MTF information, because the filterstack is not in the optical path.
Cheers,
Bart
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Hi Dean,
The filterstack is part of the optical design of modern lenses. See here (http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses) and here (http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter).
Those linked comments seem to about filter stack thickness, and indeed might reflect merely needing the correct optical distance (distance corrected for refractive index of the various layers) between lens and sensor. This does not mean that there needs to be expensive birefringent material in the construction once the lenses are designed on the assumption that an OLPF is present; just that either removing those layers or replacing them by a different material could require changing the sensor's position. If the same material needed to be there, it would have prevented Nikon from omitting the birefringent layers entirely in the D810, which instead seems to have been done with no reported disadvantage compared to the D800E. And maybe there is a reason for a given model of sensor to be shipped with at least the rear birefringent layer bonded to it, so long as _some_ cameras using that sensor will have an OLPF.