Has anyone had the opportunity to test the D800/E for diffraction limits - At which f-stop does it begin to show in the images ?
You bring up an interesting point of employing deconvolution sharpening - Could this mean that in the in the future perhaps Photoshop or other imaging editors may include deconvolution algorithms that automatically correct the effects of diffraction based on lenses and f-stop used - Something similar to the auto lens distortion correction we have in Adobe Camera Raw ?
Hello Bart :
Thanks for the reply -
You bring up an interesting point of employing deconvolution sharpening - Could this mean that in the in the future perhaps Photoshop or other imaging editors may include deconvolution algorithms that automatically correct the effects of diffraction based on lenses and f-stop used - Something similar to the auto lens distortion correction we have in Adobe Camera Raw ?
Thanks,
Jai
I would disagree with the f/5.6 figure - rather, the true figure is slightly short of f/8.
At f/5.6, the Airy disc diameter is greater than the width of a single photosite - but individual photosites do not give us pixels.
Rather, it's only at just below f/8 (around f/7.8 or so) that the Airy disc exceeds the size of a single Bayer cell, and starts to have some sort of impact on sharpness.
Hi,
I'm afraid there are a few problems with your assumptions.
- 1. At f/5.6, and a wavelength of 555 nm, the diameter of the first diffraction ring is 7.58 micron, which is 1.554x the sensel pitch of the D800/D800E. Therefore, at least 4 neighboring sensels will be affected, and another 4 are just starting to be hit. This first ring represents 83.9% of the diffraction, so there is already an additional 16.1% of energy going to surrounding sensels. This can cause interference with the Airy disk patterns of other sensels, so the signals can become substantially higher in the neigboring sensels at certain spatial frequencies.
- 2. The D800 has an OLPF (AA-filter) which spread the signal for a single sensel to about 4 sensels.
- 3. Individual photosites DO give us pixels, with 2 of the 3 channels being interpolated from surrounding photosites.
- 4. You speak of a "Bayer cell", which raises the suspicion that you erroneously think that 4 photosites make 1 pixel, they don't, they make 4 pixels, all suffering from diffraction from all of their neighbors.
Without diffraction, photography would not be very interesting. It is because we have diffraction we have images.
It is funny, back in the silver age of photography, no one seemed too concerned about diffraction. Certainly, no one changed their aperture habit based on the resolving power of the film--diffraction was just as noticeable on a piece of film at about the same apertures as digital. It is only in the digital age where we magnify images to a much greater degree that we suddenly care. I regularly print of 44" wide printers. DoF has a much more important impact on the image than diffraction. An image with too much or not enough DoF will never be as interesting as an image with the right DoF regardless of lens aberrations or diffraction.
There is something quite not exciting about photography when everyone shoots at f/8. This is a creative pursuit, not an object lesson in resolving power.
Absolutely - it is a rare voice of sense that is heard on the internet!
Does the pixel level image really matter at the end of the day? It is all about the final print surely.
Marianne Oelund (a technically savvy engineer/photographer) make an interesting comment dpreview (http://forums.dpreview.com/forums/read.asp?forum=1021&message=41372182) concerning the differences in how diffraction affects the D800 and D800E. I presume this difference is due to the lack of a low pass filter. When the Airy disc is already smaller than the pixel, making it even smaller by increasing the aperture has diminishing returns.
In the same thread, Bobn2 (http://forums.dpreview.com/forums/read.asp?forum=1021&message=41367353) posted a graph showing how the f-number at which diffraction starts to become visible has nothing at all to do with the pixel size, which is somewhat at variance with Marianne's post.
In the same thread, Bobn2 (http://forums.dpreview.com/forums/read.asp?forum=1021&message=41367353) posted a graph showing how the f-number at which diffraction starts to become visible has nothing at all to do with the pixel size ...What that graph for the Nikon 50/1.8G reminds us is that resolution is at least a three way contest between diffraction, aberrations, and sensor resolution, and that when the aperture is big enough for diffraction to stop dominating over sensor resolution (about f/8 to f/5.6), lens abberations are also a major factor. The peak of resolution does seem to shift slightly, from f/5.6 with the D3 to f/4 with the D3x, but the main effect of increased sensor resolution is to raise the resolution curve at all apertures, just raising it a bit more at f/4 than at f/5.6.
Of course the diffraction pattern doesn't get bigger or smaller when we use a different sensor but the denser sampling of the diffraction pattern does mean that the pixel contrast is reduced.And that is a good thing, a definite advantage for the denser sensor.
I don't know or care about the physics of the situation.
Most of the macro I'm shooting are tiny bugs and flowers and end up being used as 100% crops. Even at 100% and F22, the pictures are sharper than anything I've gotten with any other camera I own.
Here is an F11 version that's a 100% crop.
This is one shot at f22..
Fortunately, image quality is a subjective criteria. So basing sharpness simply on MTF or l/mm is not very useful. At any aperture, the resolving power of the D800 will always be in effect, so there is actually nothing to lose. To judge sharpness at pixel level does not have a great deal of meaning as a viewer will not be able to see the detail anyway. So the loss of sharpness because of diffraction does not lead to a softer image as perceived by the viewer and the increase in sharpness through DoF can make the image appear sharper which is far more important than any pixel level measurement of resolving power.Valid and logical points. When speaking on resolution there are many factors involved including scene frequency, and importance of detail which is subjective and based on what we see in prints. It's all tradeoffs. Some scenes have no problem printing large from lower resolution cameras, others will fall apart very quickly. If the scene has no micro detail or important micro detail, or if that detail is just too small for any system to resolve, this may influence our choice of f/stop regardless of diffraction.
Trying to dissect this problem based on numbers without reference to the human visual system, and beyond simply the resolving power of the human visual system, is really a futile exercise. Our perception of an images counts much more than reducing the problem into the ability to separate lines.
That's unfortunate, because it would allow you make a better decision when you can choose between options. Narrower apertures will not only show more sensor dust but also produce more background clutter in Macros, and microcontrast suffers, so if you can avoid it it would improve your overall image quality (you also can use shorter shutterspeeds which helps to reduce handheld motion blur).
That is unfortunately not plausible. At 100% the smaller sensels will have lower contrast than larger sensel cameras at the same aperture, or even lose all resolution at such apertures, and micro contrast detail will be lost whether we care or not. To illustrate I'll show a Macro crop from a larger sensel camera (sorry, I don't have a D800 to demonstrate it with) which demonstrates at f/8.0 what will occur at f/5.6 and narrower on the D800:(http://bvdwolf.home.xs4all.nl/temp/OPF/DiffSpotDiameter.jpg)
The 'Dsd' mentioned is the diffraction spot diameter in sensel widths.
As the theory predicts, until you reach f/16, there is still a lot that can be salvaged.
It's a pitty you can't compare it to an f/16 version, it would have been much sharper, but then maybe you don't care ... It's just too bad that people spend such an amount of money and then throw quality away by stopping down too far. Beyond f/16 there is virtually no fine detail left even in the plane of focus. At f/22 you only get, at best, some 75% of the maximum resolution that the camera is capable of as if shooting with a camera with 56% of the mega pixels, which you could put to good use. And as I said, you'll reduce your risk of motion blur if you shoot a f/16 instead.
Cheers,
Bart
You do understand that 100% monitor view does not represent any real world viewing condition. To take about sharpness in any absolute terms in regard to pixel pitch does not mean much.
The medium format camera shows far less diffraction than the 800/e at equivalent f stops.
Some tests that I reported recently in this Thread (http://www.luminous-landscape.com/forum/index.php?topic=68359.msg542223#msg542223) are not definitive, but are consistent with image degradation becoming noticeable at f/16 and smaller. F/4 to f/5.6 produce the best results with good lenses, but f/8 is quite usable.
Regards,
Bill
Some tests that I reported recently in this Thread (http://www.luminous-landscape.com/forum/index.php?topic=68359.msg542223#msg542223) are not definitive, but are consistent with image degradation becoming noticeable at f/16 and smaller. F/4 to f/5.6 produce the best results with good lenses, but f/8 is quite usable.
Regards,
Bill
So it is really showing that diffraction is a function of format,
... not pixel pitch,
when it comes to viewing images.
DoF is going to have a far greater impact on the image than diffraction ever will.
If you are shooting a D800 only at f/5.6, then you are really wasting the potential of this camera as well as limiting yourself over the control of your image.
The commonly held belief is that smaller format cameras have more depth of field than large format cameras, and this is true if the same f/stop is used.
The commonly held belief is that smaller format cameras have more depth of field than large format cameras, and this is true if the same f/stop is used. However, if the aperture size (in millimeters, not f/number) is held constant, depth of field is the same. See Roger Clark (http://www.clarkvision.com/photoinfo/dof_myth/), another PhD in physical science. Small format P&S or camera phone cameras have very small pixels, and require large apertures (low f/stop numbers) to maintain image quality. They don't even offer f/16.
Regards,
Bill
LOL. Is that all? I print single 40MP images out on 44" wide paper stock and 44" is the short edge. The 40MP images aren't even sweating at that size.
To simplify further, the formula is max f-stop = P x 1.054. The D800 has a pixel pitch of 4.87 microns, so the corresponding f/stop is f/5.1. As one exceeds this critical f/stop, loss of contrast is often more noticeable than the loss of resolution. These considerations derive from the laws of physics and are not a defect in the D800. If you use f/16 on the D800, the results will be no worse than with the D3, which has 8.4 micron pixels.
That doesn't mean anything. Why would anyone want a 150DPI print these days?
I'm sure you know, Bill, that many mathematical formulae and principles of Physics are approximations, ...
So you are trying to suggest that the laws of diffraction (http://en.wikipedia.org/wiki/Airy_disk) are not accurate, despite the fact that the phenomenon can be seen (first reports go back to 1828), measured, reproduced, and accurately calculated?
The Airy pattern falls rather slowly to zero with increasing distance from the center, with the outer rings containing a significant portion of the integrated intensity of the pattern. As a result, the root mean square (RMS) spotsize is undefined (i.e. infinite). An alternative measure of the spot size is to ignore the relatively small outer rings of the Airy pattern and to approximate the central lobe with a Gaussian profile.
Just perform the test and, if the result seems to add something worthwhile, by all means share it.
I'm sure you know, Bill, that many mathematical formulae and principles of Physics are approximations, not only for the sake of simplicity, but because of uncertaintanties built into the fabric of reality, and the ever-present possibility that sometimes mand-made theories can be either flat out wrong or plain imprecise, or that the people using the theories in any particular instance may be misapplying them.
Having taken the trouble to compare F16 images from a couple of cropped-format cameras with a much higher pixel density than the D3, and one of which has even a slightly higher pixel density than the D800 (the Canon 50D), I am confident that it is extremely unlikely that resolution at F16 with the D3 would be as good as resolution at F16 with the D800. I suspect the resolution differences would be clearly noticeable at 100% on monitor, after appropriate sharpening for each image and upsizing of the smaller file.
Now it so happens I still have my 12.7mp Canon 5D which is very close to the pixel density of the Nikon D3. If I have the time, and time really is a problem but I might be able to find it in the interests of the pursuit of truth, I could do another comparison between my old 5D used at F16 and my new D800E used at F16, to see which is sharpest.
I could take bets on the results of the outcome (to give me an incentive), but I doubt that Michael would allow betting activities on his site. ;D
More specifically, the Wikipedia article you refer to contains the following comment about the Airy disk.QuoteThe Airy pattern falls rather slowly to zero with increasing distance from the center, with the outer rings containing a significant portion of the integrated intensity of the pattern. As a result, the root mean square (RMS) spotsize is undefined (i.e. infinite). An alternative measure of the spot size is to ignore the relatively small outer rings of the Airy pattern and to approximate the central lobe with a Gaussian profile.
Hi,
It seems that different posters may have different requirements.
I do agree that viewing distance plays a crucial role. If viewing distance is increased the eye may not be resolve the finest detail. So sharpening may mask lack of detail. The picture looks sharp. Watching closer the lack of detail is obvious.
Best regards
Erik
I want people to feel free to get close and explore moving their head around a bit. You want to immerse them in a place and time they will never see again. That is worth buying. Anything less will hold interest for a few seconds only.I agree with this. The idea of a "normal" viewing distance has always been more about when the printing technology will fail (normal for a billboard vs normal for a magazine spread). to me a great image can pull you in as you "immerse yourself" (very good description) in the image. Sure, not everyone will look at it close ... they may have no interest in the subject matter.
I certainly don't want to print with such low resolution the image quality degrades very quickly as you approach the image if a viewer so chooses.
As a long time 4x5 shooter, I was under the impression that diffraction gets worse as the focal length gets shorter. I thought it was the actual size of the aperture at given f-stop, and had nothing to do with the focal length.
In other words a 150mm 4x5 lens at f16 had much less diffraction than a 50mm lens at f16 on a 35mm camera. I remember shooting at f22-32 very often with my 4x5 cameras and don't recall any sharpness issues.
I recently shot a job with my 17mm TSE Canon on my 1DsMk3 and noticed a major fall off in sharpness at anything above f11. I wonder if lenses that have mediocre sharpness to begin with don't show the effect as much?
Don't you get peeved when some photogs try to argue with you about how unnecessary they feel 30+ megapixel cameras are because of the theoretical 5-15 ft. viewing distance.
I also see light diagonal stripes on the 40D image (on the vertical dark bar just left next to the portrait) that are missing in the 50D crop. It doesn't look like aliasing, so it seems to be higher resolution (due to less diffraction?) ...
Those broad, diagonal, colored stripes that are very obvious on the 40D crop occur in a number of places around the head of the Aboriginal. Not being as knowledgeable as you on such technical matters as aliasing and moire, my first reaction was that those diagonal stripes were in fact artifacts or moire.
But I always like to do real-world checking, so I pulled out a $50 banknote from my wallet and studied it carefully with a magnifying glass.
I can assert categorically that those diagonal, faintly colored stripes do not exist on the banknote. They are false detail.
Quote
In other words a 150mm 4x5 lens at f16 had much less diffraction than a 50mm lens at f16 on a 35mm camera. I remember shooting at f22-32 very often with my 4x5 cameras and don't recall any sharpness issues.
That is because the image (and the diffraction) requires less output magnification for a given output size. The f/16 on the 35mm image was magnified much more. The f/22 - f/32 required much less magnification so the actual diifraction patterns stayed small enough to not affect output sharpness too much.
Does this apply to stitching too? Or is it related to the actual size of the negative/sensor relative to the aperture size?
Let´s say I stitch 3 images taken in portrait mode so the resolution of the digital "negative" is increased to 7360x10000 pixels. In order to print it horizontally on a 110cm roll I would have to interpolate the image to about 200% (or reduce the resolution to 150ppi) whereas a regular d800 image file (7360 × 4912px) would have to be interpolated about 280-300%. Is this what is meant with magnification?
It appears to me that stitching (if that suits your shooting style) could be one way to avoid diffraction problems when you want that ultra-deep DOF??
Does this apply to stitching too? Or is it related to the actual size of the negative/sensor relative to the aperture size?
Let´s say I stitch 3 images taken in portrait mode so the resolution of the digital "negative" is increased to 7360x10000 pixels. In order to print it horizontally on a 110cm roll I would have to interpolate the image to about 200% (or reduce the resolution to 150ppi) whereas a regular d800 image file (7360 × 4912px) would have to be interpolated about 280-300%. Is this what is meant with magnification?
It appears to me that stitching (if that suits your shooting style) could be one way to avoid diffraction problems when you want that ultra-deep DOF??
The f/16 image may look sharp when viewed at long distance, but fine line pattern visible in the red box is very clearly lost on the f/16 image.
What seems to be missing from the more diffraction affected 50D image crop, is the diagonal area detail in the 40D crop, that I marked in Red (the vertical bar) on the attached copy of your image.
It does help if we do not have to magnify the existing diffraction to the point that it becomes clearly visible as lost reolution. However, for a given Field of View it won't help to just stitch some more images together, because that will only increase our FOV. While that helps to reach a certain output size with a lower output magnification, it may not give us the FOV we want, it may be too wide. To counter-act that, one typically shoots with a longer focal length with a narrower FOV but unfortunately also a shallower DOF. To compensate for that one could use a narrower aperture, but that defeats the purpose of reducing the visibility of diffraction blur.
Ray, you are trying to confuse things for fun. We all know the 40d or the 50d both have the ability to take a picture with high detail. All those artefacts are the product of your digital manipulation of the file, not the cameras. You down-sampled the hell out of it then blew it up over 200%. The moire was created by your down-sampling not diffraction.
My mistake then. I don't understand how you can get that size of aliasing.
Very interesting and informational review.
Many of the discussed points apply not only to Nikon cameras, but also to other FX and DX models, especially the diffraction issue and "bigger crop" trap.
http://www.bythom.com/nikond800review.htm (http://www.bythom.com/nikond800review.htm)
I'm finding a lot of folk picking up the D800 models fall into the Big Croppers group: they're buying a D800 because it allows them to crop dramatically. As in pulling out 12mp pieces from a 36mp source. I'm not sure why these folk think that's any different than owning a D7000. If you're always cropping that much, the D7000 is actually slightly better than the D800 in terms of pixel density (very slightly: 16mp DX on the D7000 versus 15mp DX on the D800), plus you'll save enough money to buy some lenses that'll let you crop less.
I have been testing a D800E using a Hartblei 40/4 TS. There is no question in what I am seeing on the screen at 100%, both sharpness and contrast fall off substantially at f/16. I want DOF, but not at the cost of losing substantial contrast and detail. I have not printed any files as yet, but for now and depending on the composition, I'll be sticking with f/8 or f/11 for landscapes. F/8 is really outstanding, so I'll frequently bracket these two apertures and decide in PP on which one to keep.
Hi,
It actually has to do with the angular aperture, and as such both the actual aperture size and the focal length are in play. However, since our aperture numbers (F-number) are a ratio (f/#) between focal length and aperture size, diffraction is constant (as is the angular aperture) at a given F-number.
That is because the image (and the diffraction) requires less output magnification for a given output size. The f/16 on the 35mm image was magnified much more. The f/22 - f/32 required much less magnification so the actual diifraction patterns stayed small enough to not affect output sharpness too much.
For the 1DsMk3, f/11 is probably the sweetspot where corner resolution has improved enough and center resolution has fallen enough to provide even sharpness across the image-circle, I know it does on my TS-E 24mm II. Optical theory predicts that center resolution will start to be visually impacted by diffraction at apertures narrower than f/7.1 on the 1DsMk3. It's not the optical quality, which probably is second to none, but pure physics.
Cheers,
Bart
Excellent explanation, thank you.
Hi,
Bart says that according to theory onset diffraction can be seen on 1DsIII at f/7.1.
I made a series of test shots with a 16 MP APS-C camera which has similar pixel pitch to the D 800/E and I'd suggest that diffraction is clearly visible at f/8. Se left column of the linked page: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/49-dof-in-digital-pictures?start=1
On the other hand, diffraction is benign to sharpening. We are loosing edge contrast which can be regained with proper sharpening. Stopping down to far would reduce resolution, too. Lost resolution cannot be restored.
...
Obviously this is a huge area for individual opinions.
...
Paul