Thorsten wrote:
Over on Nikongear, Bjorn Rorslett wrote that aliasing will hit worst when shooting very fast lenses (f/1.4 and faster) wide open, though I have no idea about the theory behind it. He posted some examples, too.
that sounds crazy to me. things have to be in focus to cause aliasing. most (certainly not all though) lenses that fast cannot resolve enough detail wide open to provoke moire (the lens itself acts as an AA filter). more importantly though, when you shoot at those apertures the dof of field is so slim you won't even notice the moire. a one cm thick plane of focus falling on part of a dress is not going to create any image ruining aliasing artifacts. the only way this would become an issue is if somebody is shooting something flat and in the focus plane wide open with one of the best f/1.4 lenses made. so really only people who shoot flat art pieces made of textiles at f/1.4 will have such issues.
f/2.8 to f/5.6 and shooting people with a flash is where the real difficulty will be. i have to say i'm surprised by the f/9 moire examples as diffraction should already be limiting resolution at f/9 if i remember correctly? i guess just not enough.
It's an excellent discussion of whether AA-less sensors give your actual resolution or spurious resolution. Don't get discouraged by the fact that it seems to be an argument about sharpening at first :-)
Makes me think that I should have ordered one of each -- a D800 and a D800E -- and done a full on comparison just to resolve the debate in that thread.
sebboh wrote:
that sounds crazy to me. things have to be in focus to cause aliasing. most (certainly not all though) lenses that fast cannot resolve enough detail wide open to provoke moire (the lens itself acts as an AA filter). more importantly though, when you shoot at those apertures the dof of field is so slim you won't even notice the moire. a one cm thick plane of focus falling on part of a dress is not going to create any image ruining aliasing artifacts. the only way this would become an issue is if somebody is shooting something flat and in the focus plane wide open with one of the best f/1.4 lenses made. so really only people who shoot flat art pieces made of textiles at f/1.4 will have such issues.
f/2.8 to f/5.6 and shooting people with a flash is where the real difficulty will be. i have to say i'm surprised by the f/9 moire examples as diffraction should already be limiting resolution at f/9 if i remember correctly? i guess just not enough....Show more →
The sample Bjorn posted is with the D3x and f/1. Crazy or not, it's reality. I downloaded it and checked the EXIF. But I agree in practical use you will more often get moire in the scenarios you described.
Thorsten wrote:
The sample Bjorn posted is with the D3x and f/1. Crazy or not, it's reality. I downloaded it and checked the EXIF. But I agree in practical use you will more often get moire in the scenarios you described.
you'll have to show me the link for me to know what you're talking about, but the d3x has an AA filter and there isn't an f/1 lens that will show it's aperture in exif on a nikon camera. for that matter, i'm not aware of an f/1 lens that is mountable on a nikon camera without a serious mount conversion.
sebboh wrote:
you'll have to show me the link for me to know what you're talking about, but the d3x has an AA filter and there isn't an f/1 lens that will show it's aperture in exif on a nikon camera. for that matter, i'm not aware of an f/1 lens that is mountable on a nikon camera without a serious mount conversion.
sebboh wrote:
you'll have to show me the link for me to know what you're talking about, but the d3x has an AA filter and there isn't an f/1 lens that will show it's aperture in exif on a nikon camera. for that matter, i'm not aware of an f/1 lens that is mountable on a nikon camera without a serious mount conversion.
That is strange. Is the D3x with AA filter removed?
I remember there is a thread post by Ron in Leica thread talk about Moire happened in one of his client's cloth. He remove the moire by brush out the alias color and paint/(spot,replace) back original color. Unless you are doing some fabric ad shot, you won't even notice for Portrait. Most of your attention will be the person in your picture but the fabric detail.
thanks, had not even heard of that lens, sound interesting though.
i see the image, but it is small (is it a crop?) and i don't see any moire or other high frequency aliasing. i do see CA and visual illusions associated with such b&w line and grid patterns.
rico wrote:
The 800E has exactly the same resolution as the 800,
I don't think that is right. The two cameras have the same pixels and the same pixel count, but I suspect the actual resolution recorded by the two cameras to be different. We will have to wait and see the results of a resolution test for proof.
sebboh wrote:
i see the image, but it is small (is it a crop?) and i don't see any moire or other high frequency aliasing. i do see CA and visual illusions associated with such b&w line and grid patterns.
It's a crop. The target is a simple pattern of black lines. Look at the "zipper" going thru the image at the middle right side. I have seen similar "zippers" in M9 images.
Thorsten wrote:
It's a crop. The target is a simple pattern of black lines. Look at the "zipper" going thru the image at the middle right side. I have seen similar "zippers" in M9 images.
that is a low frequency aliasing effect, that as far as i know cannot be avoided with an AA filter – all of my cameras will do that if i shoot a pattern like that with an f/1.2 lens at mfd. it has never come up for me in any real world shooting (i guess it could if shooting a brick wall at angle at f/1.2 at close distance is what you want to shoot).
Lotusm50 wrote:
I don't think that is right. The two cameras have the same pixels and the same pixel count, but I suspect the actual resolution recorded by the two cameras to be different. We will have to wait and see the results of a resolution test for proof.
That the 800 and 800E have the same resolution may sound like a truism, but is also likely true in fact. The caveat is testing both sensors with the same input that is free of frequencies higher than the sensor-site pitch can properly sample. As mentioned in prior FM threads, it is sufficient to stop down to reach that threshold of blur. Alternatively, use a conforming test pattern. If chroma/luminance moire can be induced, the image is invalid and resolution measurements from it are invalid. Such a determination is distinct from personal preferences for "crispy" images. I like crispy, too, but only in my cereal or fish-n-chips.
sebboh wrote:
that is a low frequency aliasing effect, that as far as i know cannot be avoided with an AA filter – all of my cameras will do that if i shoot a pattern like that with an f/1.2 lens at mfd. it has never come up for me in any real world shooting (i guess it could if shooting a brick wall at angle at f/1.2 at close distance is what you want to shoot).
just to clarify what i wrote above: the staggered zipper pattern is caused by the lens being so far out of focus that it can no longer resolve the frequency of the pattern being shot (which is of course a much lower frequency than what any AA filter blocks out). the effective "sampling frequency" of the lens drops below the spatial frequency of the lines on the paper leading to an aliasing effect. the only way an AA filter would prevent this is if it was set so low that the camera could not resolve the lines on the paper when focused properly (meaning the paper would look like a solid grey sheet of paper instead of lined paper).
rico wrote:
That the 800 and 800E have the same resolution may sound like a truism, but is also likely true in fact. The caveat is testing both sensors with the same input that is free of frequencies higher than the sensor-site pitch can properly sample. As mentioned in prior FM threads, it is sufficient to stop down to reach that threshold of blur. Alternatively, use a conforming test pattern. If chroma/luminance moire can be induced, the image is invalid and resolution measurements from it are invalid. Such a determination is distinct from personal preferences for "crispy" images. I like crispy, too, but only in my cereal or fish-n-chips....Show more →
quote from Nikon
"Nikon engineers have developed a unique alternative for those seeking the ultimate in definition. The D800E incorporates an optical filter with all the anti-aliasing properties removed in order to facilitate the sharpest images possible.
This is an ideal tool for photographers who can control light, distance and their subjects to the degree where they can mitigate the occurrence of moiré. Aside from the optical filter, all functions and features are the same as on the D800."
"The D800E reproduces the texture of the stone pavement and twigs with higher resolution than the D800. It allows sharper rendering with depth. "
Again either you choose a low pass filter in front of all your images to suffer slightly high frequency/micro contrast loss or you choose no low pass filer bare slightly chance to get moire or high frequency alias, but with sharper image have more micro-contrast.
If AA is heavy enough to immure Moire, you have to attenuate your freq response much earlier than half of your sampling frequency. You may have the same resolution but you loose micro contrast, which is dull in image to put it strong.
Nikon is thinking that for 36M, D800E has reach the possibility to remove AA filter. You certainly can disagree, it has nothing to do with your cereal or fish-n-chips.
In the end, you must decide if you believe Nyquist–Shannon. If you're mathematically inclined, feel free to prove (or disprove) the theorem. Nikon Marketing means well, but their main task is selling digital cameras to the masses. Of course, there are implementation details such as the point-spread function of birefringent crystal covers. That is why I performed a couple of studies using real images from a Canon 1Ds (weak AA). The results are not uplifting. With weak or absent low-pass filtering, there will be oversampling in both theoretical and empirically-observable form. Sorry.
Lotusm50 wrote:
Makes me think that I should have ordered one of each -- a D800 and a D800E -- and done a full on comparison just to resolve the debate in that thread.
Spurious resolution is a phenomenon that just as I think someone mentioned is amplified by shooting large-aperture lenses wide open. It has nothing to do with pixel-scale aliasing/moire, even though it is a form of low frequency aliasing.
The reason for the increased "risk" of getting spurious resolution in OOF areas with large aperture lenses is that they are often overcompensated for SA at maximum aperture. This is what gives "bright-outer-ring" background bokeh. When light is stronger at the rim of the blur discs and you put two such blur discs close to each other, the small region where the bright edges intersect will be the brightest part of the image area. This might very well mean that a black area in the middle between two white areas (now I'm talking about the actual, physical target in front of the camera) may become the brightest part of the image region, even though the target is "black" here.
(BTW)
The Printing Nikkors and the APO_EL Nikkors are the sharpest lenses I've ever tried measuring, short of narrowband collimators. The 105mm printing Nikkor is diffraction limited at wide open (!) the very edge of the 44mm image circle, at 1:1 magnification. Between 400-700nm....
You sometimes see them discussed in specialist pre-press circles, and by some very specialized macro shooters, since this performance is only there at the magnification rate the lens was built for.
(BTW2)
That 85mm F1.0 lens is quite interesting, since the virtual aperture (that needs to be 85mm in diameter to make the 85mm focal length f/1.0) - is actually larger than the diameter of the lens... :-)
At first I couldn't get my head around it, but then someone more used to macro/repro optics than me explained that the 1.0 designation is only valid for very close range work. As you look into the lens from the front from a very close distance, it actually looks like the lens is physically larger on the inside than on the outside (?!) - a very cool effect. This is because the entire front part of the optical construction is positive, magnifying the virtual image of the insides - the aperture. And the virtual image of the aperture is what counts when you define the light gathering ability (F-stop is defined at infinity focus in most "normal applications" otherwise).
theSuede wrote:
Spurious resolution is a phenomenon that just as I think someone mentioned is amplified by shooting large-aperture lenses wide open. It has nothing to do with pixel-scale aliasing/moire, even though it is a form of low frequency aliasing.
I mentioned the spurious resolution link for those engaged in this subtopic and the image showing an example of it:
I like crispy, too, but only in my cereal or fish-n-chips.