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Author Topic: 5Ds vs 5DsR - the true resolution difference?  (Read 27784 times)

ErikKaffehr

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Re: 5Ds vs 5DsR - the true resolution difference?
« Reply #40 on: February 20, 2015, 12:23:53 PM »

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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DeanChriss

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Re: 5Ds vs 5DsR - the true resolution difference?
« Reply #41 on: February 21, 2015, 10:14:13 AM »

...
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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BJL

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Re: 5Ds vs 5DsR - why twin birefringent layers fon non-OLPF version, again
« Reply #42 on: February 21, 2015, 10:40:15 AM »

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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BartvanderWolf

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Re: 5Ds vs 5DsR - the true resolution difference?
« Reply #43 on: February 21, 2015, 02:21:50 PM »

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 and here. 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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== If you do what you did, you'll get what you got. ==

ErikKaffehr

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Re: 5Ds vs 5DsR - the true resolution difference?
« Reply #44 on: February 21, 2015, 02:55:20 PM »

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 and here. 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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BJL

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Re: 5Ds vs 5DsR - the true resolution difference?
« Reply #45 on: February 21, 2015, 03:30:21 PM »

Hi Dean,

The filterstack is part of the optical design of modern lenses. See here and here.
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.
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