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Author Topic: 24mp D7100 announced, has no AA filter  (Read 6103 times)
BernardLanguillier
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« Reply #20 on: February 24, 2013, 11:42:15 AM »
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Assuming that making a FF sensor is a simple "extrapolation" of making a crop sensor, technologically and economically.

One might assume that making a spacecraft is just like making an aeroplane, only that it has to fly higher. I am sure that people at institutions like NASA can tell us why it is not so.

Hum... I am not sure that the analogy accurately reflects the level of challenge at stake here.

Cheers,
Bernard
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JonathanRimmel
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« Reply #21 on: February 24, 2013, 05:18:14 PM »
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Well, I sure hope the D400 is still coming. (Despite the evidence against it)  I wouldn't want to give up the pro features of my D300 even if the 7100 has some very nice specs.  But really a D400 with 16MP, Pro body with pro controls and a useable ISO 6400+ at 8fps+ would be fantastic. I don't know, the D7100 just seems too different from my D300 to be a merger of the 7000 & 300.  With the Canon 7D MK II rumors flying around, who knows perhaps there is hope for a Pro DX body yet!
« Last Edit: July 01, 2013, 04:35:56 PM by JonathanRimmel » Logged
BernardLanguillier
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« Reply #22 on: February 24, 2013, 07:03:47 PM »
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Buffer, pro body, and maybe a new autofocus system, or the one from the D4 /D800 series.  

On the AF side it seems that the D7100 already meets your expectation, it appears to be using the same module as the D4.

On the body side, the weather sealing is arguably the most important feature, and here also it is already D800 spec. It remains to be seen whether the lack of full metal body has an actual impact for day to day usage.

So this leaves mostly the buffer, which would have been a low cost item for Nikon. So this confirms clearly that the D400 is coming.  Smiley

As far as I am concerned, my D7000 is now the property of another family member so that, for the first time in many years, I do not have any back up DSLR in case my D800 fails... it makes the D7100 a very appealing option but I will probably wait a few months for its retail price to settle a bit around summer time frame.

Cheers,
Bernard
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mac_paolo
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« Reply #23 on: February 25, 2013, 01:30:38 AM »
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Most probably we'll have a D400 body this year:

http://forums.dpreview.com/forums/thread/3387936#forum-post-50901841

I keep my fingers crossed.
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hjulenissen
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« Reply #24 on: February 25, 2013, 02:08:07 AM »
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Hum... I am not sure that the analogy accurately reflects the level of challenge at stake here.
You may very well be right.

I believe that empiry suggests that sensel-level technology that is state-of-the-art at smaller sensor sizes seldom is introduced at the same time at larger (FF,MF) sizes. This would suggest that, for whatever reason, taking that 24MP D7100 sensor and making a 54 MP FF sensor of equal quality anywhere near the timeframe of the D7100 is unlikely.

What could be the reason?
1. Startup cost. Even if each camera is sold for $7000 this may or may not make up for the large series of $600 cameras sold. Hasselblad will probably not be able to hire 1000 R&D Engineers no matter how high their prices. Canon might be _able_ to do this for their "professional" series, but it might not make economic sense.
2. Complexity scaling nonlineary with sensor area. It is my understanding that making a good 24x36mm sensor is quite hard, that you have to use specialized equipment and/or reuse logic circuitry infra-structure in novel ways. Is it such a large leap to suggest that this is easier by using "mature" or "conservative" sensel designs?

-h
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BJL
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« Reply #25 on: February 25, 2013, 08:22:36 AM »
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Assuming that making a FF sensor is a simple "extrapolation" of making a crop sensor, technologically and economically.

One might assume that making a spacecraft is just like making an aeroplane, only that it has to fly higher. I am sure that people at institutions like NASA can tell us why it is not so.
Well, you do not need to be a rocket scoentist to know that a jet cannot function in a vacuum. The difficulties in scaling up a given sensel design from 24x18mm to 36x24mm are not so great, and history stongly suggests that it can be done, with
- a few years of work
- lower frame rates due to the longer signal paths and greater amount of data to move
- quadrupling or so of the component cost, due to the need for stitching in fabrication and so on.

But another scaling issue comes from fundamental optics; specifically the trade-offs between diffraction and DOF. In the sort of photography that benefits from resolutions even higher than 36MP, sharpness requirements typically involve needs for adequate DOF, and getting equal DOF in a larger format requires a proportionately higher aperture ratio and thus proportionately larger diffraction spot sizes, setting a proportionately lower limit on absolute resolution in l/mm.

This increases the "minimum useful pixel size". In fact, with a given desired DOF for a scene, diffraction sets an upper limit on overall image resolution in "lines per picture height" or "useful pixel count" which does not depend on format size. With all the comments in these forums for some years now from medium format using professionals that there is not much _professional_ use for resolutions more than about 22 or 30 or 40 MP, I wonder how much market there would be for a 35mm format body with 50MP+, when the "low res." alternative at a mere 36MP could offer higher frame rates and overall faster processing, both in-camera and in-computer.

For some professionals and perhaps more so from some passionate amateurs like "stitchers", there is no such thing as too many pixels --- but are there _enough_ of these customers, willing to spend enough money, in order to make such a camera commercially viable?
« Last Edit: February 25, 2013, 09:10:54 AM by BJL » Logged
MrSmith
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« Reply #26 on: February 25, 2013, 10:11:58 AM »
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"I wonder how much market there would be for a 35mm format body with 50MP"

If it had live view, good dynamic range, produced good files at 800+ iso, cost less than 5k and had a range of high quality lenses that cost between 1-2k available then I would think the market would be large enough to be worth investing funds in development of that camera body.
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BJL
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« Reply #27 on: February 25, 2013, 04:46:01 PM »
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"I wonder how much market there would be for a 35mm format body with 50MP"

If it had live view, good dynamic range, produced good files at 800+ iso, cost less than 5k and had a range of high quality lenses that cost between 1-2k available then I would think the market would be large enough to be worth investing funds in development of that camera body.
Any evidence or reasoning behind that prediction? Of course, there is already some market for DMF backs at over 50MP, but AFAIK, only a  few thousand a year of those are sold, with development costs defrayed by selling at far higher prices than you mention, so the sales numbers would have to be far greater to be of interest to a company like Nikon or Canon or Sony.

Especially if the development costs include a bunch of sufficiently sharp new lenses. Erik will likely mention how well some 35mm format lenses perform in the "center crop" of a 24MP APS-C bodies, but the challenge is for the lenses to perform well over the full frame, not just near the center, and I do not know how current 35mm format lenses fair on that standard.
« Last Edit: February 25, 2013, 04:47:40 PM by BJL » Logged
bill t.
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« Reply #28 on: February 25, 2013, 05:25:06 PM »
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Don't I recall seeing a press release about Zeiss supposedly developing a line of FF super-lenses?  And of course cinema lenses have been made to exceptional quality for decades, for a price and size penalty.

Would be perfectly happy with a camera such that I could make 40 x 60 prints at 300 native camera pixels per inch, with nothing larger than an FF sensor, with perfect quality free of any sort of diffraction or quantum related compromise.  Nikon and Canon can stop there, if they want.
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BernardLanguillier
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« Reply #29 on: February 25, 2013, 06:26:03 PM »
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Especially if the development costs include a bunch of sufficiently sharp new lenses. Erik will likely mention how well some 35mm format lenses perform in the "center crop" of a 24MP APS-C bodies, but the challenge is for the lenses to perform well over the full frame, not just near the center, and I do not know how current 35mm format lenses fair on that standard.

I guess that my focus on stitching changes the equation completely, but as far as I am concerned I don't need anything wider than 50mm and we already have amazing options today, even without mentioning the new Zeiss 55mm.

Anyway, this isn't really about needs. It hasn't been for years really, has it? Nobody really would need 80mp backs if the neighbours didn't have one and if the previous backs had been close to where they needed to be from a usability standpoint. Nobody really needs any 35mm sensor better than the one of the D3x.

But technology marches on because camera companies need to maintain a constant revenue stream to satisfy their stock owners. This isn't really about photographers but better lenses will follow, there is zero doubt about the fact that we will have 50mp full frame sensors soon.

When depends on a few factors that are likely to be more business related than technology related at Nikon. They will probably wait to let people buy enough D800/D800e before killing it with even better performance, but I don't think they are likely to let Canon re-take the crown in the high performance body segment for more than a few days.

Just guessing obviously.

Cheers,
Bernard
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FredBGG
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« Reply #30 on: February 25, 2013, 10:04:55 PM »
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Obviously they will want to improve the high ISO image quality and a reasonnable frame rate, so they may prefer to stick to a lower pixel count to increase the universality of the camera, but if they wanted to really produce a landscaper camera focusing on ISO 100-1600 range with max 3 images per second, I do not see any technological hurdles preventing them from announcing it next week.

Cheers,
Bernard


A FF would be twice the size of this:



[url]http://chsvimg.nikon.com/lineup/dslr/d7100/img/sample/img_01_l.jpg[url]

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Ray
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« Reply #31 on: February 25, 2013, 11:18:03 PM »
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But another scaling issue comes from fundamental optics; specifically the trade-offs between diffraction and DOF. In the sort of photography that benefits from resolutions even higher than 36MP, sharpness requirements typically involve needs for adequate DOF, and getting equal DOF in a larger format requires a proportionately higher aperture ratio and thus proportionately larger diffraction spot sizes, setting a proportionately lower limit on absolute resolution in l/mm.

This increases the "minimum useful pixel size". In fact, with a given desired DOF for a scene, diffraction sets an upper limit on overall image resolution in "lines per picture height" or "useful pixel count" which does not depend on format size. With all the comments in these forums for some years now from medium format using professionals that there is not much _professional_ use for resolutions more than about 22 or 30 or 40 MP, I wonder how much market there would be for a 35mm format body with 50MP+, when the "low res." alternative at a mere 36MP could offer higher frame rates and overall faster processing, both in-camera and in-computer.

Especially if the development costs include a bunch of sufficiently sharp new lenses. Erik will likely mention how well some 35mm format lenses perform in the "center crop" of a 24MP APS-C bodies, but the challenge is for the lenses to perform well over the full frame, not just near the center, and I do not know how current 35mm format lenses fair on that standard.

BJL,
All lenses, possibly without exception, have worse performance at the edges and in the corners, and such worse performance seems to be always noticeable regardless of the sensor's resolution, in my experience.

It's true that, as the pixel count of a given format of sensor increases, the improvement in sharpness and detail will be most apparent when the lens is used at its sharpest aperture, such as F4 or F5.6, and in the centre the resulting image.

If the lens used has rather poor performance at the extreme edges, there may be no noticeable improvemet in resolution at such edges when the pixel count of the sensor is increased. However, resolution at those edges can never be worse as a result of increasing sensor resolution, and is likely to be at least very marginally better, even if to an insignificant degree.

I don't find the argument convincing that increasing the resolution of the sensor serves little purpose without improved lenses that are sharp to the very corners.
There are two basic ways in which the resulting image will benefit from an increase in sensor resolution, such as from 36mp to 54mp, using any reasonably good lens.

(1)  Centre resolution will be noticeably better at apertures up to and including F11, which may not be of concern for small prints, but may well be of concern when photographing a small bird at a distance, using one's longest telephoto lens.

(2) At sufficiently large print sizes which allow one to discern the improved image resolution in the centre, it is true that the areas in the image which are OoF will not appear sharper than they are in the image from the lower-resolution sensor.

In this sense, the DoF in the image from the higher-resolving sensor might appear to be slightly shallower at any given F/stop, not because the blurred bits are even more blurred, but because the sharp, in-focus bits, are noticeably sharper.

However, in situations where extensive DoF is desired, the higher-pixel-count sensor provides one the option of sacrificing the benefits of a sharper central resolution, by stopping down to a degree which results in a resolution (in the plane of focus) which is equal to that of the lower-pixel-count sensor, but not worse. DoF in such circumstance will then be greater in the image from the high-resolving sensor.

In other words, a 54mp full-frame 35mm sensor, with lens used at F8, will provide about the same centre resolution as the 36mp sensor with same lens used at F5.6 (assuming the lens is sharpest at F5.6). However, the increased DoF at F8, compared with F5.6, will be very noticeable, and far more noticeable than the reduced DoF one would get from the 54mp image, using both sensors at F5.6.

A similar situation would apply when comparing the 54mp sensor with lens at F11, and the 36mp sensor with the same lens set at F8. Sharpness and detail in the plane of focus will be about equal in both images, but the 54mp image will have very noticeably greater DoF.

This all might sound a bit convoluted, but it is easy to check such issues for oneself, if one still owns a lower-resolving cropped-format DSLR as well as a more recent, higher-resolving upgrade.
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MrSmith
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« Reply #32 on: February 26, 2013, 03:21:14 AM »
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"Any evidence or reasoning behind that prediction?"
Just development in lenses from Nikon, Canon, Zeiss and sigma plus the fact that sensors of the higher pixel pitch required exist in the market in crop format already. Fabricating at full frame cannot be a huge technological leap.

We have 40mpixel cameras on phones so why not?
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BJL
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« Reply #33 on: February 26, 2013, 09:21:14 AM »
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To all those who have responded to my previous posts, let me first explain that I was genuinely asking a question about if and when there will be a _business case_ (adequate return on investment) for Nikon to acquire and deploy a sensor of about 56MP or more in a 36x24mm format camera. I am not at all ruling it out, just being skeptical about the line of reasoning that "it is technically possible and some people always crave more MP, therefore it will be done". Note that neither Canon nor Sony have apparently yet seen a business case for going beyond 22 or 24 MP, even though Sony at least clearly has the sensor technology (and the Zeiss lenses too!)

One question:
Ray says that diffraction effects will only be limiting from about f/11 up; what is the evidence on this? AFAIK, theres is already some significant diffraction limitation by f/8 with the D800E, but I do not know far beyond that one can push before diffraction truly dominates resolution.

Some comments:
1) The business case for high end SLRs seems to depend heavily on profits from high end lens sales too, so Nikon will have little interest in making such a camera on the basis of needing Zeiss lenses: the question is how well Nikon's own lens system will benefit from such a sensor, and how much (if any) extra investment would be needed in new Nikon lenses.

2) Of course lenses perform worse near the edges, especially normal to wide angle ones, but there is still an issue of _acceptable_ edge performance, and that is not addressed by testing with sensors of the desired pixel size over only a central crop to less than half the total image area. Also, it seems that a lot of interest in very high resolutions is in the realm of wide-angle scenes (landscapes and such), so for non-stitchers at least, adequate performance of those normal-to-wide lenses over the whole frame is a significant issue.

3) f/8 to f/11 sounds like plenty of DOF, but that is based on experience with standard viewing conditions, viewing from a distance about equal to or greater than image diagonal size. But under those viewing conditions not much more than 12MP is relevant, due to the eye's resolution limit of somewhere around 1/3500th of viewing distance. To see the difference between 36MP and an even higher resolution image, you need to be viewing at distance about half or less of the image width (say to examine details within the frame by moving close to a big print, zooming in on the screen, cropping massively, etc.) and that doubling of viewing angle also halves the DOF by making OOF effects twice as visible. Then those closely viewed details in an f/8 image show only the DOF associated with f/4 in "normal viewing" of a 35mm format image, and likewise f/11 "looks like" f/5.6. That is why the overall trend is for higher pixel counts to need higher f-stops to adequately control OOF effects on image sharpness.

On the other hand, portraits should work fine, with their typically low DOF and the good performance of the longer than normal focal lengths used ... for the few faces in the world that can stand scrutiny at 56MP!

4) The idea of packing 56 million 4 micron pixels into a high end, relatively low frame rate 36x24mm body for the sake of crops to a lower pixel count from long telephoto lenses makes little sense to me: if the cost and weight of such a lens and body are "within budget", then so would be adding something like a D7100 (or hoped-for D400) to use with that lens for those shots.
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Ray
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« Reply #34 on: February 26, 2013, 09:26:54 PM »
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One question:
Ray says that diffraction effects will only be limiting from about f/11 up; what is the evidence on this? AFAIK, theres is already some significant diffraction limitation by f/8 with the D800E, but I do not know far beyond that one can push before diffraction truly dominates resolution.

All the testing that I've done on this issue tends to indicate that 35mm-format lenses are not fully diffraction limited till about F22. The most rigorous testing I did a few years ago, comparing my 10mp Canon 40D with the 15mp 50D (25mp versus 38mp when interpolated to full-frame), showed clearly that the higher pixel-count sensor produced more detailed results at all F/stops up to and including F16. The resolution difference in the centre was of the order of about one full f/stop, ie, F16 on the 50D was about equal to F11 on the 40D,  F11 on the 50D was about equal to F8 on the 40D, and F8 on the 50D was actually much better than F5.6 on the 40D because the 40D image was spoiled by significant moire at F5.6. Whilst the resolution differences between the 50D at F16 and the 40D at F11 were impossible to discern at 100% on screen, the increased DoF of the 50D at F16 was very obvious.

Quote
The idea of packing 56 million 4 micron pixels into a high end, relatively low frame rate 36x24mm body for the sake of crops to a lower pixel count from long telephoto lenses makes little sense to me: if the cost and weight of such a lens and body are "within budget", then so would be adding something like a D7100 (or hoped-for D400) to use with that lens for those shots.

If that were the only benefit of the 56mp full-frame, then I agree it wouldn't make much sense. Fortunately, there are other benefits, especially for those who like to use  high quality prime lenses. For example, a 50mm prime lens on a D7100 becomes equivalent to a 75mm lens on a full-frame body, in terms of FoV, regardless of sensor resolution.

However, if the full-frame sensor has the same pixel density and same pixel quality as the D7100 (as the D800 has compared with the D7000), then a basic 50mm/F1.4 lens on the full-frame body becomes effectively a very high quality 50-75mm zoom with a constant maximum aperture of F1.4, and the new Nikkor 70-200/F4 becomes a 70-300/F4 zoom with the remarkable characteristic that at all focal lengths between 200mm and 300mm the centre resolution remains constant but edge resolution actually improves, becoming best at 300mm. Wow!

Which lens would you rather have, a 105-300/F4, or a 70-300/F4 of equal weight and price, and on balance, better quality?

I use the term "on balance" in relation to quality, because there will usually be minor differences in image quality depending on which camera the 70-200/F4 is attached to, but on balance the quality of the 70-200 on a 56mp FX camera should be better. For example, if the scene requires a focal length of 150mm on the full-frame, then the same zoom attached to the D7100 would need to be used at 100mm. Comparing the resulting 24mp image from the D7100 with the 56mp image from the full-frame, one would almost certainly find that centre resolution in the image from the 56mp FX camera would be better if the lens was used at its sharpest apertures on both cameras. However, edge resolution might be slightly worse in the FX image.

On the other hand, if DoF and edge sharpness were an issue, then one might decide to sacrifice the advantage of the sharper centre resolution that 56mp affords, for the benefits of increased DoF and better edge sharpness.

In other words, for equal DoF from the FX camera at 150mm, the lens would need to be stopped down approximately one stop. Stopping down on the FX camera might either increase centre resolution or decrease it, depending on which aperture one is stopping down from. Stopping down from the maximum aperture of the lens, which is rarely its sharpest aperture, will not only improve edge performance, but also centre performance. In such circumstances the edge resolution in the FX image at, say F4, might be at least the equal of the edge resolution in the DX image shot at F2.8 (it would be reasonable to suppose) but the centre resolution in the FX image, having the benefits of both a sharper aperture and a higher pixel count, should be very noticeably better.

However, in circumstances where the stopping down with the FX, to equalize DoF and improve edge performance, is from a smaller aperture such as F5.6 to F8 or F8 to F11, the image quality from both cameras should be pretty close.

In summary, any FX lens on a full-frame body will be a more flexible lens with a greater effective range of focal lengths, potentially producing better and sharper results and never producing worse results than the same lens on a DX body of equal pixel quality and pixel density.

A slower frame rate need not be an issue. The D800 has approximately the same frame rate as the D7000 when the D800 is used in DX mode (6fps), and likewise one would expect any forthcoming 56mp FX camera from Nikon to have the same frame rate in DX mode as the new D7100, which is also 6fps.
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mac_paolo
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« Reply #35 on: February 27, 2013, 02:37:43 AM »
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I thought this thread was about the new D7100 cameraRoll Eyes

Maybe it should be renamed to "Speculations on yet-to-be-released 54 MP full frame sensors.Undecided
Yawn.
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Ray
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« Reply #36 on: February 27, 2013, 09:36:58 AM »
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Some of us are concerned with the bigger picture, which includes the D7100 of course.  Wink
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BartvanderWolf
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« Reply #37 on: February 27, 2013, 02:11:53 PM »
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One question:
Ray says that diffraction effects will only be limiting from about f/11 up; what is the evidence on this? AFAIK, theres is already some significant diffraction limitation by f/8 with the D800E, but I do not know far beyond that one can push before diffraction truly dominates resolution.

The sensel pitch of the D7100 is probably something like 3.917 micron. That means that at the Nyquist frequency of 127.7 cycles per millimetre, with f/14 diffraction (at 564nm wavelength) reducing the MTF to zero at 125 cy/mm, there is zero resolution left for such fine detail (regardless of its contrast) at the limit of the possible sensor resolution that can be achieved with wider apertures. Narrower apertures will reduce the absolute limit of resolution even more. A D800 (4.88 micron sensel pitch) would hit that zero contrast limit at 2/3rd stops narrower, at f/18.

Visible deterioration of microcontrast will start much earlier at wider apertures, assuming one uses the large number of pixels for large output or significant cropping. Downsampling of the image willobviously hide the lack of resolution.

Cheers,
Bart
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Ray
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« Reply #38 on: March 01, 2013, 12:03:05 AM »
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The sensel pitch of the D7100 is probably something like 3.917 micron. That means that at the Nyquist frequency of 127.7 cycles per millimetre, with f/14 diffraction (at 564nm wavelength) reducing the MTF to zero at 125 cy/mm, there is zero resolution left for such fine detail (regardless of its contrast) at the limit of the possible sensor resolution that can be achieved with wider apertures. Narrower apertures will reduce the absolute limit of resolution even more. A D800 (4.88 micron sensel pitch) would hit that zero contrast limit at 2/3rd stops narrower, at f/18.

Visible deterioration of microcontrast will start much earlier at wider apertures, assuming one uses the large number of pixels for large output or significant cropping. Downsampling of the image willobviously hide the lack of resolution.

Cheers,
Bart

Hi Bart,
Those figures seem about right to me. If the Canon 50D with a pixel pitch of 5.63 microns can continue to deliver discernibly higher resolution up to F16 (compared with a 40D with a pixel pitch of 5.63 microns), then one would expect a sensor with an even smaller pixel pitch of 3.92 microns (such as the D7100) to be limited to providing more  detail up to and including F11 (approximately), compared with a camera such as the D7000 with a pixel pitch of 4.72 microns, especially considering that the D7100 has no AA filter, which must give it an additional slight resolution advantage however small that may be.

That you've calculated the theoretical cut-off point to be F14, implies there would probably be a discernible improvement in detail up to F11 approximately. F13 would be too close to the cut-off point. But even at F11, one would expect such improved detail only to be discernible at 100% on monitor, or on very large prints at least 4ftx6ft, or on smaller prints of significant crops of the full image.

It is that last advantage of the potential of small crops that is of practical significance, so it's not surprising that Nikon have included a 1.3x crop mode on top of the already physically cropped-format of 1.5x, which results in a 14.4mp image, a faster frame rate of 7fps, and an equivalent focal length of 2x the 35mm-format focal lengths.

Just out of curiosity, I compared the DXOMark results at the pixel level (screen mode) for the 15mp Canon 50D, which I still use with my Canon 100-400 zoom, and the new Nikon D5200 which DXO have already tested.

Since the D5200 also has a 24mp sensor and 14 bit processing, just as the D7100 has, one would not expect the test results for the D5200 to be any better than the newer, more expensive and more professional D7100. In fact, one might reasonably expect the D7100 results to be at least very marginally better in some respects.

With this in mind, I was very interested to compare the D5200 pixel with the Canon 50D pixel. There's hardly any practical resolution difference between a 14.4mp image and a 15mp image, but there certainly is a difference between an effective 1.6x focal length and a 2x focal length.  A 400mm lens on the 50D becomes effectively a 640mm lens, whereas a 400mm lens on the D7100, in cropped mode, becomes effectively an 800mm lens.

However, the D7100 pixel is significantly smaller than the 50D pixel (3.92 versus 4.68 microns) so I wondered whether such a 14.4mp crop would suffer any quality disadvantages compared with the full 15mp 50D image, such as lower SNR perhaps, or worse color sensitivity.

Wow! Was I surprised! Pleasantly surprised, of course. After scrutinising the charts and graphs comparing sensors at the pixel level, expecting to see at least some marginal benefit of the larger 50D pixel, at least in some respect, I could not find any improvement in any respect whatsoever, however marginal.

The best the 50D can do is approximately match the Tonal Range and 'SNR at 18%' results for the D5200 pixel, but only at ISOs of 200 and higher. For the other parameters of DR and Color Sensitivity, the smaller D5200 pixel is streets ahead, at all ISOs.

DR is a whopping 2 stops better at base ISO, as one might expect, but also 0.75EV better at ISO 6400. Color Sensitivity is a very significant 2 bits better at base ISO and about 1 to 1.2 bits better at all higher ISOs.

The more recent 18mp Can 7D is even worse at the pixel level. See for yourselves at:
http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/(appareil1)/850%7C0/(brand)/Nikon/(appareil2)/619%7C0/(brand2)/Canon/(appareil3)/272%7C0/(brand3)/Canon

The bottom line for me is that I shall have no concerns at all about lower image quality in any respect (compared with my 50D), when using the cropped mode on the D7100 for a longer reach than I get with my Canon 50D, which is good news.

The bad news is that Nikon do not have a good quality, reasonably lightweight, 400mm/F5.6  prime or zoom that compares with the Canon offerings. I'm a bit reluctant to get the Sigma 150-500/F6.3 because of reports that this lens is sharpest only at F11, at the long end.

Cheers!

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Ray
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« Reply #39 on: March 01, 2013, 06:52:32 PM »
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Actually, I've just realised that according to Nikon's brochure, the 1.3x crop mode of the D7100 results in a 15.4mp image, not 14.4mp as I wrote above, so that means it's an almost exact match to my old 50D in terms of pixel count.

Some might think this crop mode is an irrelevancy because one can always crop the image later in post processing, and an image with a larger FoV provides more cropping options as one considers and reconsiders the possibilities.

However, in my opinion, the main advantages of using the crop mode is that it increases the frame rate from 6fps to 7fps, and probably increases the number of images the buffer can hold, although I'm not certain about this.

The buffer size of only 6, RAW, uncompressed, 14 bit images seems a bit inadequate for sports and wildlife shooting. However, as I understand, the number of images the buffer can hold increases in 12 bit mode, and increases again for lossless compression, as opposed to uncompressed RAW. Whether or not it increases yet again in cropped mode is not certain.

Another advantage of cropped mode is the greater number of images the memory card can hold, which is not much of an advantage considering the huge capacity of the latest SDHC cards, but it might be a concern if one is in a situation where one frequently shoots till the buffer fills.
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