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#71
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Nikon new release D7100
On 06/03/2013 12:10, Wolfgang Weisselberg wrote:
David Taylor wrote: However, there is the question whether give (a) a sufficiently high number of pixels (pixel density on the focal plane), http://www.dpreview.com/reviews/sonyslta65/13 http://www.dpreview.com/reviews/nikon-d3200/13 24 MPix APS-C (equivalent to 54 or more MPix FF) and you *still* get moire. On test patterns. (b) a lens with either a very shallow depth of field or being slightly out of focus, And *hope* the critical parts are OOF? Fun. Not. Agreed - I didn't answer my question, merely posed it! (c) a lens with an MTF which is quite low at the critical spatial frequency, whether the aliasing which may exist is of sufficiently great an amplitude that it makes a material difference to the picture. And use a ... weak ... lens? Yep, that's why people buy an expensive high resolution DSLR. Given a sufficiently high pixel density the lens MTF will be approaching zero. The question is when does that happen with real equipment in real photo-taking situations? Likely different for different folk. There is a substantial difference between a low-cost 'phone camera (and an inherently great depth of field) and a high-pixel-density full-frame sensor used with a wide-aperture lens. Yep: the phone camera has an insane pixel density, the FF DSLR does not. -Wolfgang But not with the example of aliasing which was shown. For all we know, the sensor in a low-cost 'phone may not even have an AA filter. All I'm saying is that it's (excuse the pun) not black and white. Given a sufficiently high pixel density, the AA filter may not be required under certain circumstances, and as pixel density increases, those criteria are increasingly likely to be encountered. (Compare audio, where an increased sampling rate (density) allows a much less "brick-wall" filter to be used.) -- Cheers, David Web: http://www.satsignal.eu |
#72
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Nikon new release D7100
In article , David Taylor says...
Given a sufficiently high pixel density the lens MTF will be approaching zero. The question is when does that happen with real equipment in real photo-taking situations? Likely different for different folk. You have this belief that the pixel count in the D7100 is high enough, which in fact is based on no hard data. It's more prudent to assume that the D7100 will in certain cases suffer from moiré, and therefore shouldn't be used for critical work, for instance on a fashion show. -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site |
#73
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Nikon new release D7100
On 06/03/2013 18:33, Alfred Molon wrote:
In article , David Taylor says... Given a sufficiently high pixel density the lens MTF will be approaching zero. The question is when does that happen with real equipment in real photo-taking situations? Likely different for different folk. You have this belief that the pixel count in the D7100 is high enough, which in fact is based on no hard data. It's more prudent to assume that the D7100 will in certain cases suffer from moiré, and therefore shouldn't be used for critical work, for instance on a fashion show. Please don't put words into my mouth. I am asking the question, opening the discussion, not giving a definitive answer. -- Cheers, David Web: http://www.satsignal.eu |
#74
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Nikon new release D7100
David Taylor wrote:
On 06/03/2013 12:10, Wolfgang Weisselberg wrote: David Taylor wrote: However, there is the question whether give (a) a sufficiently high number of pixels (pixel density on the focal plane), http://www.dpreview.com/reviews/sonyslta65/13 http://www.dpreview.com/reviews/nikon-d3200/13 24 MPix APS-C (equivalent to 54 or more MPix FF) and you *still* get moire. On test patterns. So you say test patterns can never appear in, say, fabrics? (c) a lens with an MTF which is quite low at the critical spatial frequency, whether the aliasing which may exist is of sufficiently great an amplitude that it makes a material difference to the picture. And use a ... weak ... lens? Yep, that's why people buy an expensive high resolution DSLR. Given a sufficiently high pixel density the lens MTF will be approaching zero. 54 MPix on FF is NOT enough. See above. The question is when does that happen with real equipment in real photo-taking situations? Likely different for different folk. No, the question is: do individual photographers mind having moire at times, or not? There is a substantial difference between a low-cost 'phone camera (and an inherently great depth of field) and a high-pixel-density full-frame sensor used with a wide-aperture lens. Yep: the phone camera has an insane pixel density, the FF DSLR does not. But not with the example of aliasing which was shown. For all we know, the sensor in a low-cost 'phone may not even have an AA filter. When the airy disk is always sufficiently larger than the pixel size an AA filter can't improve anything any more. All I'm saying is that it's (excuse the pun) not black and white. Given a sufficiently high pixel density, the AA filter may not be required under certain circumstances, and as pixel density increases, those criteria are increasingly likely to be encountered. I agree. I just disagree with you that current DSLR pixel counts are close to a 'sufficiently high pixel density'. (Compare audio, where an increased sampling rate (density) allows a much less "brick-wall" filter to be used.) Yep, and what are the current sample rates -- 192 kHz for consumers? And we can hear, what, 22kHz at best --- so that's a 4 times overscan (above the needed 44 or 48 kHz). At a back-of-the-envelope calculation, you'd need about 0.25 nm pixel size for f/1.2; which means about 96,000 x 144,000 pixels at FF, which comes to 13824 MPix (about 14 GPix). Somehow 38 MPix seems a bit low compared to that. -Wolfgang |
#75
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Nikon new release D7100
Wolfgang Weisselberg wrote:
At a back-of-the-envelope calculation, you'd need about 0.25 nm pixel size for f/1.2; which means about 96,000 x 144,000 pixels at FF, which comes to 13824 MPix (about 14 GPix). Somehow 38 MPix seems a bit low compared to that. In fact 150MP is getting close, and 250MP is certainly enough that no anti-aliasing filter will be needed. That is based on a diffusion limited lens with an f/1.2 aperture. Hence something between 175 and 200MP is a pretty fair estimate for the pixel count needed to simply eliminate the need for any anti-aliasing filter on a 36x24mm sensor. Which is interesting, given that it would appear that technology is just around the corner and will likely be available in the next decade. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
#76
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Nikon new release D7100
On 10/03/2013 12:37 PM, Floyd L. Davidson wrote:
Wolfgang Weisselberg wrote: At a back-of-the-envelope calculation, you'd need about 0.25 nm pixel size for f/1.2; which means about 96,000 x 144,000 pixels at FF, which comes to 13824 MPix (about 14 GPix). Somehow 38 MPix seems a bit low compared to that. In fact 150MP is getting close, and 250MP is certainly enough that no anti-aliasing filter will be needed. That is based on a diffusion limited lens with an f/1.2 aperture. Hence something between 175 and 200MP is a pretty fair estimate for the pixel count needed to simply eliminate the need for any anti-aliasing filter on a 36x24mm sensor. Which is interesting, given that it would appear that technology is just around the corner and will likely be available in the next decade. The next FF nikon looking likely to be 44Mp, now that's a worry, thinking storage space. |
#77
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Nikon new release D7100
On 2013-03-09 19:20:01 -0800, Rob said:
On 10/03/2013 12:37 PM, Floyd L. Davidson wrote: Wolfgang Weisselberg wrote: At a back-of-the-envelope calculation, you'd need about 0.25 nm pixel size for f/1.2; which means about 96,000 x 144,000 pixels at FF, which comes to 13824 MPix (about 14 GPix). Somehow 38 MPix seems a bit low compared to that. In fact 150MP is getting close, and 250MP is certainly enough that no anti-aliasing filter will be needed. That is based on a diffusion limited lens with an f/1.2 aperture. Hence something between 175 and 200MP is a pretty fair estimate for the pixel count needed to simply eliminate the need for any anti-aliasing filter on a 36x24mm sensor. Which is interesting, given that it would appear that technology is just around the corner and will likely be available in the next decade. The next FF nikon looking likely to be 44Mp, now that's a worry, thinking storage space. Not to worry. It will come with its very own SATA SSD slot/dock. ....but no CF or SDHC slot. ;-) -- Regards, Savageduck |
#78
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Nikon new release D7100
On 09/03/2013 11:03, Wolfgang Weisselberg wrote:
David Taylor wrote: [] All I'm saying is that it's (excuse the pun) not black and white. Given a sufficiently high pixel density, the AA filter may not be required under certain circumstances, and as pixel density increases, those criteria are increasingly likely to be encountered. I agree. I just disagree with you that current DSLR pixel counts are close to a 'sufficiently high pixel density'. Again, you are putting words in my mouth which I didn't say. There is no definitive value for "sufficiently high" - it depends on the lens, the scene and the photographer's requirements. It appears that for today's combinations of those variables, with 24 MP DX cameras and 36 MP full-frame cameras we are either approaching or have reached "sufficiently high" for many people for much of the time. Test cases, super-expensive lenses, and particular subjects excepting. -- Cheers, David Web: http://www.satsignal.eu |
#79
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Nikon new release D7100
In article , David Taylor says...
Again, you are putting words in my mouth which I didn't say. You keep writing that, then you come up with statements as the below one in which you claim that "... we are either approaching or have reached "sufficiently high" ...". Perhaps we are not close yet to the "sufficiently high". There is no definitive value for "sufficiently high" - it depends on the lens, the scene and the photographer's requirements. It appears that for today's combinations of those variables, with 24 MP DX cameras and 36 MP full-frame cameras we are either approaching or have reached "sufficiently high" for many people for much of the time. -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site |
#80
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Nikon new release D7100
David Taylor wrote:
On 09/03/2013 11:03, Wolfgang Weisselberg wrote: David Taylor wrote: [] All I'm saying is that it's (excuse the pun) not black and white. Given a sufficiently high pixel density, the AA filter may not be required under certain circumstances, and as pixel density increases, those criteria are increasingly likely to be encountered. I agree. I just disagree with you that current DSLR pixel counts are close to a 'sufficiently high pixel density'. Again, you are putting words in my mouth which I didn't say. There is no definitive value for "sufficiently high" - it depends on the lens, the scene and the photographer's requirements. It appears that for today's combinations of those variables, with 24 MP DX cameras and 36 MP full-frame cameras we are either approaching or have reached "sufficiently high" for many people for much of the time. Test cases, super-expensive lenses, and particular subjects excepting. Where it is that you get that idea is totally beyond my comprehension! 36MP is not even close, unless you stop the lens down to f/45 or something very small to get excessive diffraction. -- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) |
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