# AA filter in the 5D mark IV



## Lenscracker (Aug 29, 2016)

I have seen nothing that suggests how much or what sort of AA filter is in the new 5D4. I really love the results I get with my 5Dsr. The effective removal of the AA filter has made a huge difference in the sharpness in the photos I get from the 5Dsr. I am not sure that I want another camera with an AA filter that is as heavy as the one on the 5D3. What is so difficult about making the AA filter switchable, or making it an option? Pentax does it.


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## neuroanatomist (Aug 29, 2016)

Pentax's 'switchable' AA filter isn't an optical low pass filter OLPF), but rather a simulated AA filter effect accomplished by moving the sensor during image capture. It uses their in-body image stabilization,so don't expect to see it on a Canon body any time soon. One potential with Pentax's approach is limited effectiveness at high shutter speeds (which would be a problem for me, for example, since bird feathers can show moiré and I generally use shutter speeds >1/1000 s).

Worth noting that Nikon patented a modified where (I'll simplify) a transmissive LCD is used in the OLPF and can be used for a low-pass canceling filter (light is split in one direction then recombined, vs. being split in one direction then the other). Because it's an LCD, it can be turned on or off.


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## Act444 (Aug 29, 2016)

Not sure 100%, but judging from the samples DPR posted, there certainly appears to be a filter - perhaps even slightly stronger(?) than the one in the 5D3...

https://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=canon_eos5dmkiv&attr13_1=canon_eos5dmkiii&attr13_2=canon_eos5dsr&attr13_3=canon_eos5ds&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=800&attr16_1=800&attr16_2=800&attr16_3=800&attr171_3=off&normalization=full&widget=1&x=0.4848647313366422&y=1.0164753417379968


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## scyrene (Aug 29, 2016)

It's good to like the kit one uses, but is there really much of a difference? Has anyone posted good evidence that removing the AA filter adds much appreciable sharpness? I hear these rather hyperbolic statements and demands on the subject, but reasoned comment has suggested that appropriate sharpening can all but cancel out the difference between e.g. the 5Ds and 5DsR - does anyone have anything definitive on this? Is it just a marketing gimmick that people have bought into?


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## tron (Aug 29, 2016)

scyrene said:


> It's good to like the kit one uses, but is there really much of a difference? Has anyone posted good evidence that removing the AA filter adds much appreciable sharpness? I hear these rather hyperbolic statements and demands on the subject, but reasoned comment has suggested that appropriate sharpening can all but cancel out the difference between e.g. the 5Ds and 5DsR - does anyone have anything definitive on this? Is it just a marketing gimmick that people have bought into?


I do not think so. AlanF who uses 5DsR for birding a lot said that the lack of AA filter reduces the need for sharpening thus keeping the noise lower.


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## Act444 (Aug 30, 2016)

RickSpringfield said:


> After seeing this in action ... I give the IQ award to the 5DSR:
> 
> https://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=canon_eos5dmkiv&attr13_1=canon_eos5dmkiii&attr13_2=nikon_d810&attr13_3=canon_eos5dsr&attr15_0=jpeg&attr15_1=jpeg&attr15_2=jpeg&attr15_3=jpeg&attr16_0=100&attr16_1=100&attr16_2=100&attr16_3=100&attr171_3=off&normalization=full&widget=1&x=-0.8905680083682159&y=0.177578358350828
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> *Better pick up a body while they last. * Thinking sales of the 5DSR are going to skyrocket!



I agree...and I'm doing just that!  

This is the push I needed. Will be a nice compliment to my 5D3, and I can skip the 4.


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## East Wind Photography (Aug 30, 2016)

Act444 said:


> RickSpringfield said:
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> > After seeing this in action ... I give the IQ award to the 5DSR:
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But the 4 is all about pushing shadow detail 6 stops!


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## East Wind Photography (Aug 30, 2016)

Act444 said:


> Not sure 100%, but judging from the samples DPR posted, there certainly appears to be a filter - perhaps even slightly stronger(?) than the one in the 5D3...
> 
> https://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=canon_eos5dmkiv&attr13_1=canon_eos5dmkiii&attr13_2=canon_eos5dsr&attr13_3=canon_eos5ds&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=800&attr16_1=800&attr16_2=800&attr16_3=800&attr171_3=off&normalization=full&widget=1&x=0.4848647313366422&y=1.0164753417379968



It will be stronger due to the increase in pixel density. Every incremental increase in resolution requires a bit stronger AA filter. Even the 5dsr doesnt remove the filter, they just cancel it with another filter.


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## Act444 (Aug 30, 2016)

East Wind Photography said:


> Act444 said:
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> > Not sure 100%, but judging from the samples DPR posted, there certainly appears to be a filter - perhaps even slightly stronger(?) than the one in the 5D3...
> ...



I'm aware of the R's cancelled filter, but the other tidbit I didn't know, that's interesting. Still, even the regular 5DS (with filter) is noticeably sharper than those 5D4 crops so there has to be more to it.


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## East Wind Photography (Aug 30, 2016)

Act444 said:


> East Wind Photography said:
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Yes there is more to it. The big one is almost twice the mp with the 5ds. Other factors that affect things, pixel density, pixel size, dual pixel, digic processor.

i compared images taken with the 7d mark ii and the 5ds on loan from cps at around the same pixel scale...that is an approximately close estimate of the same number of pixels across a subject and found little difference in image sharpness. If fact i saw very little difference in noise and noise patterns. The big difference was that the 5ds just had more pixels to work with.

The 5dsr was noticeably sharper but noise and patterns were still the same. I owned it for about 6 months. The purchase was my biggest mistake. Pure GAS purchase.

Anyway, i ended up trading in my 5dsr for a 1dx2 and kept my 7d2 as a backup. I shootly mostly sports and wildlife and the 5dsr was just too slow for most of my paid work. Do i miss it? Not at all. At times it would be nice but i wasnt using it enough to justify keeping it. High iso was poor and under stadium lighting it was a big stretch even with an f2.8 lens.

The 5dsr would make a great landscape camera and might be a good fair weather wildlife camera (more static use and less action). Its certainly not too rugged and not weather sealed as good as the 1dx2.... But i digress...


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## aa_angus (Aug 30, 2016)

Those comparison photos make the 5DIV look absolutely awful..what's going on? It can't actually be that bad


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## AlanF (Aug 30, 2016)

East Wind Photography said:


> Act444 said:
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My 5DS R when cropped to the same size as my 7D2 is certainly both noticeably sharper and less noisy. I work so much at the limits of resolution with telephoto lenses that I appreciate the 50 mp. The 5D IV is on my watch list as there are occasions when fewer mp. But, I wish Canon would have ditched the AA filter. Some commenter on DPR (not a troll) wrote that its presence was good for video but not for stills. 

ps Intuitively, I would have thought that smaller pixels would require weaker filters as the defocussing would be over a smaller area.


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## scyrene (Aug 30, 2016)

tron said:


> scyrene said:
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> > It's good to like the kit one uses, but is there really much of a difference? Has anyone posted good evidence that removing the AA filter adds much appreciable sharpness? I hear these rather hyperbolic statements and demands on the subject, but reasoned comment has suggested that appropriate sharpening can all but cancel out the difference between e.g. the 5Ds and 5DsR - does anyone have anything definitive on this? Is it just a marketing gimmick that people have bought into?
> ...



I know, and while I respect photographers' opinions, that's not the same as presenting evidence. Is it even possible to quantify sharpness?


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## tron (Aug 30, 2016)

scyrene said:


> tron said:
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1. Preferring the results.
2. Comparing with Canon DPP's by using the sharpness slider. 

And/Or you can ask Alan (2 entries above)


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## scyrene (Aug 30, 2016)

tron said:


> scyrene said:
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I don't like bothering people  Anyway, preference is not quantification, right? We all have preferences, that doesn't make them objectively better.

I've personally never felt the AA filter had a negative effect on my pictures, but then it's hard to know without using a camera without. I just don't get how some people can claim it's a make or break thing - and that AA filters are definitely terrible and ruining their photos and any camera released with one is crippled, as some people around the place have done at times. Or to quote the OP "[t]he effective removal of the AA filter has made a *huge difference* in the sharpness in the photos I get from the 5Dsr".

The only side-by-side comparison I've seen is the dpreview test scene, and I can't see a big difference. The 5DsR is a little sharper, but it doesn't seem to be resolving much more detail, if any, and upping the sharpening on the 5Ds file would cancel out most of the difference, by the look of it.


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## tron (Aug 30, 2016)

scyrene said:


> tron said:
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The issue is by upping sharpness noise increases (ISO depended I guess)
Also you need 2 cameras (5DsR and 5Ds or 7D2) to compare. I have 7D2 and I am tempted since everyone says that a similarly cropped 5DsR is better.


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## Deleted member 378221 (Aug 30, 2016)

scyrene said:


> The only side-by-side comparison I've seen is the dpreview test scene, and I can't see a big difference. The 5DsR is a little sharper, but it doesn't seem to be resolving much more detail, if any, and upping the sharpening on the 5Ds file would cancel out most of the difference, by the look of it.



Well, that's probably because the 5DsR _does_ have an AA filter, it just uses a cancelling filter later in the stack, to...well...cancel it out...however that works. I'm not an expert in optics at that level.

You can see a difference comparing the D800 and D800E, which has a "true missing" AA Filter: Link

However, that missing AA filter can result in nasty moire in fine details, so it's not all sunshine: Link

Personally I'm torn. While I'd have liked a sharper image, I certainly never want to see image defects like with my second link.


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## scyrene (Aug 30, 2016)

tron said:


> scyrene said:
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Yeah, not many people have a 5Ds and 5DsR (or D800 and D800E) so side by side comparisons are hard to come by!  The noise issue is a bit of a red herring in my opinion - if you apply sharpening to the whole image indiscriminately, then sure it'll add noise. But that's rarely the right way to do it. The threshold should be higher, so it's only applying to the sharpest areas, and in that case adds very little noise.


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## scyrene (Aug 30, 2016)

Loibisch said:


> scyrene said:
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> > The only side-by-side comparison I've seen is the dpreview test scene, and I can't see a big difference. The 5DsR is a little sharper, but it doesn't seem to be resolving much more detail, if any, and upping the sharpening on the 5Ds file would cancel out most of the difference, by the look of it.
> ...



Good point. I'm not sure how that affects things either.


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## neuroanatomist (Aug 30, 2016)

scyrene said:


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The canceling AA filter vs. no filter would nave minimal if any difference. 

An AA filter is two sheets of a birefringent crystal material (lithium niobate) with a 1/4-wave plate in between them. The birefringent crystal spreads the light into two images offset a very tiny amount in one direction (e.g. vertical), then the 1/4-wave plate rotates the light 90°, then the second birefringent crystal spreads it a small amount in the other direction (e.g. horizontal). The 'strength' of the AA filter is determined by the thickness of the lithium niobate crystal sheet. 

In a self-canceling AA filter, they omit the 1/4-wave plate and have the two birefringent crystals in opposite orientations, so the first one spreads (for example) vertical the images, then the second one recombines the images.


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## Deleted member 378221 (Aug 30, 2016)

neuroanatomist said:


> In a self-canceling AA filter, they omit the 1/4-wave plate and have the two birefringent crystals in opposite orientations, so the first one spreads (for example) vertical the images, then the second one recombines the images.


Thanks for the explanation. But maybe you can answer one more thing:
Why on earth would you do that instead of just leaving the filter out? ;D


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## neuroanatomist (Aug 30, 2016)

Loibisch said:


> neuroanatomist said:
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> > In a self-canceling AA filter, they omit the 1/4-wave plate and have the two birefringent crystals in opposite orientations, so the first one spreads (for example) vertical the images, then the second one recombines the images.
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Because doing so allows you to make cameras both with and 'without' the AA filter while keeping all the other aspects of the production the same, since both flavors will have the same thickness of glass/etc. on top of the sensor (they replaced the 1/4-wave plate with clear glass). For example, with the self-cleaning sensor, it's not the sensor itself that vibrates, but rather some parts of the filter stack over the sensor that are moved by a piezoelectric motor. Changing the composition of the filter stack would mean different designs would be needed for the self-cleaning unit. Those sorts of things mean higher design and production costs, which means lower profits. Companies care about those sorts of things... ;D

Both Canon and Nikon used the self-canceling filter for the 'two flavor' models (D800/E, 5Ds/R). With the D810, Nikon no longer offered an AA-filtered version, so that camera just omitted the lithium niobate filters entirely.


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## Deleted member 378221 (Aug 30, 2016)

Ok, that's what I always assumed, thanks for confirming it.


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## jeffa4444 (Aug 30, 2016)

Another reason both Nikon & Canon did it that way was to maintain the same back-focus as the filter stack is part of the overall optical design. 
Retaining an AA filter in the 5D MKIV is almost certainly because of the 4K video element on a moving image aliasing / moiré is not a pleasant feature and all the high end cameras like a Arri Alexa or Red Dragon still retain them (Red even has different versions).


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## AlanF (Aug 30, 2016)

Scyrene
Here are some quantitative measurements from MTFs of various lenses on the 5DIII, 5DS and 5DS R

https://www.lensrentals.com/blog/2015/06/canon-5ds-and-5ds-r-initial-resolution-tests/

Alan


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## scyrene (Aug 30, 2016)

AlanF said:


> Scyrene
> Here are some quantitative measurements from MTFs of various lenses on the 5DIII, 5DS and 5DS R
> 
> https://www.lensrentals.com/blog/2015/06/canon-5ds-and-5ds-r-initial-resolution-tests/
> ...



That's very kind, thanks


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## midluk (Aug 31, 2016)

East Wind Photography said:


> It will be stronger due to the increase in pixel density. Every incremental increase in resolution requires a bit stronger AA filter.


Isn't the AA filter supposed to make the image satisfy the Nyquist–Shannon sampling theorem?
From this I would deduce that the AA filter strength should be proportional to the pixel pitch and therefore higher resolution requires a weaker AA filter.


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## Mikehit (Aug 31, 2016)

That is my understanding too. Moire is reduced by higher pixel density


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## neuroanatomist (Aug 31, 2016)

midluk said:


> East Wind Photography said:
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> > It will be stronger due to the increase in pixel density. Every incremental increase in resolution requires a bit stronger AA filter.
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True – East Wind Photography is incorrect.


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## StudentOfLight (Aug 31, 2016)

I think the 5D-IV IQ looks very promising based on the DPR studio shots:


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## East Wind Photography (Aug 31, 2016)

neuroanatomist said:


> midluk said:
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Please share some links so we can better understand. Higher pixel pitch should produce more moire on finer detail and therefore a higher degree of aa is required. However, I'm not afraid to stand corrected. Just trying to understand the reason for the opposite.

Incremental increases in sensor resolution have pretty consistently caused a loss of sharpness. Resolution does increase detail but the two are different.


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## neuroanatomist (Aug 31, 2016)

East Wind Photography said:


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I haven't run across anything that delves into clear detail about the 'strength' of an AA filter, but maybe it's confusion about semantics? 

An AA filter essentially spreads the incoming light (introduces blur), and the amount of that spread is proportional to the pixel pitch. So, as pixel pitch gets smaller (more MP for the same size sensor), the amount of blur that the AA filter needs to introduce to counteract aliasing also gets smaller. I think convention would say that a filter that introduces _less_ blur is a weaker filter. 

What an AA filter does is to add blur to prevent the aliasing (e.g. moiré) caused by repeating patterns in a subject where the periodicity is approximately half that of the pixel pitch or higher (Nyquist limit). Incidentally, that's why the AA filter is also called an optical low pass filter (OLPF) – it allows frequencies lower than the cutoff to pass, while blocking (blurring out, in this case) higher frequencies. For example, if a sensor's pixel pitch is 6 µm (the 5DIII is close), then patterns that repeat every 3 µm would be at the Nyquist frequency, patterns repeating every 4 µm would be lower than the Nyquist frequency, and patterns repeating every 2µm would be above it. It's the 'at or above' that the filter is designed to reduce/eliminate.

But it's a bit more complex than that, for two reasons. The first is that lenses aren't perfect. As pixel pitch decreases, eventually the blur introduced by the optics will reduce and potentially obviate the need for an AA filter. If you use crappy lenses, you won't have to complain about moiré.  The second (and for now, more important) reason is that manufacturers make choices regarding the strength of the AA filter – it's not simply 'set it equal to the Nyquist limit for the sensor' and be done. 

There are plenty of examples of moiré in images from cameras with an OLPF, I know I've seen it in bird feathers and buildings with my 1D X. Also, moiré is more evident in video than in still photography – that's because it's not just the frequencies of the patterns, it's also the alignment of the patterns in the subject with the pixel array on the sensor. For example, if you take two shots of the same brick wall (same camera, lens, etc.) but move the camera 1 cm to the left, you may see moiré in one image but not the other. But if you're panning a video across that brick wall, you _will_ see the moiré at some point in the footage. 

So, if you're a camera maker you need to decide – do you make the AA filter stronger (set the cutoff lower than the Nyquist frequency for the sensor). If you do that, you will reduce moiré in both stills and video, and if you make it strong enough, you can make pretty darn sure that none of your users see moiré. But as you make the AA filter stronger, you introduce more blur, and that means softer images. Granted, the softness introduced by an AA filter is very amenable to sharpening, but that can have undesirable consequences too (accentuates noise, but you can do NR, but that softens the image again, etc.). Or, you can make the filter weaker (less blur) – or eliminate it entirely – which means a sharper native image but a higher propensity to show aliasing. 

There's also a third reason, concerning your statement that, "Incremental increases in sensor resolution have pretty consistently caused a loss of sharpness." That's partly down to technique and camera build. With a lower resolution sensor, a given amount of camera shake (from any source, including mirror/shutter vibration) or subject motion might fall above the Nyquist frequency of the sensor. So for the 5DIII's 6 µm pixel pitch, if the camera is vibrating at an amplitude of 2.5 µm, you would not see any shake-induced blur. But if you switch to a 5Ds with a 4 µm pixel pitch, now that same amount of shake is below the the Nyquist limit, and you'll see the effect.


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## Maiaibing (Aug 31, 2016)

scyrene said:


> I know, and while I respect photographers' opinions, that's not the same as presenting evidence. Is it even possible to quantify sharpness?


Yes it is. 

If you use the link above to dpreview you can download and /or check out the difference of the visible lines between the 5DIV and 5DS/R. It is - extremely - easy to see that the 5DS/R has much more detail than the 5DIV. You can simply see the lines along he ruler the whole way up to 50 while the lines blur to extinction already around the 38 mark on the 5DIV test photo.

I was quite surprised that the difference was so big and it seems accurate to say that the extra MPIX and no AA filter gives the 5DS/R a 50% advantage over the 5DIV.

However, noise seems clearly better on the 5DIV and I expect (but have no proof or tests) DR will also be better because Canon has said improved DR was one of three key goals with the 5DIV compared to the 5DIII (the 5DS/R already has up to 2 full stops better DR than the 5DIII).


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## neuroanatomist (Aug 31, 2016)

Maiaibing said:


> If you use the link above to dpreview you can download and /or check out the difference of the visible lines between the 5DIV and 5DS/R. It is - extremely - easy to see that the 5DS/R has much more detail than the 5DIV. You can simply see the lines along he ruler the whole way up to 50 while the lines blur to extinction already around the 38 mark on the 5DIV test photo.
> 
> I was quite surprised that the difference was so big and it seems accurate to say that the extra MPIX and no AA filter gives the 5DS/R a 50% advantage over the 5DIV.



Yes, the lack of an AA filter results in sharper images, _if_ you compare ± AA filter with no sharpening or with the same amount of sharpening. However, you cannot apply much sharpening to an image from an AA-less camera before you start to see sharpening artifacts, whereas you can apply substantially more sharpening to the AA-filtered image. So in practice (i.e. where you appropriately post-process your images), although the lack of an AA filter will result in sharper images, the difference is no where near what the typical (somewhat misleading) comparisons show. 

Of course, that applies when you're only looking at the effect of an AA filter. Comparing the 5DIV to the 5Ds, you'd see a significant advantage for the latter due to the extra resolution, with only a minor bump when going to the 5DsR (and assuming your image has no moiré). Also, there's a caveat about judging fine details on DPR's comparator at the present time, and they indicate that by coloring the little 'i' (information) icon yellow for the 5DIV images – they're processed using a beta version of ACR, and while Adobe has time to make the software read the images, they likely have not optimized it for that particular sensor (which is why it's a beta version). Kudos to DPR for calling that out with the icon color...yellow = caution.


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## East Wind Photography (Aug 31, 2016)

neuroanatomist said:


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That is a great explanation and further clarifies a lot of what we are seeing in the real world. I guess that since many of these dslrs are expected to shoot video that the AA filters are probobly not at the nyquist limit. An ideal still camera may be easier to tweak at the design phase than one that has to do everything and still look acceptable to the populous.

I also still see a lot of confusion over the term sharpness vs detail and that may have been where i erred in my statement. All is well in the continuum.


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## midluk (Aug 31, 2016)

neuroanatomist said:


> What an AA filter does is to add blur to prevent the aliasing (e.g. moiré) caused by repeating patterns in a subject where the periodicity is approximately half that of the pixel pitch or higher (Nyquist limit). Incidentally, that's why the AA filter is also called an optical low pass filter (OLPF) – it allows frequencies lower than the cutoff to pass, while blocking (blurring out, in this case) higher frequencies. For example, if a sensor's pixel pitch is 6 µm (the 5DIII is close), then patterns that repeat every 3 µm would be at the Nyquist frequency, patterns repeating every 4 µm would be lower than the Nyquist frequency, and patterns repeating every 2µm would be above it. It's the 'at or above' that the filter is designed to reduce/eliminate.


I think you did the factor 2 in the wrong direction. With 6 μm pixel pitch, your Nyquist limit is at 12μm. A sinusoidal signal that repeats every 12μm has its maximum and minimum 6μm apart.

Of course the Bayer pattern complicates the situation for image sensors. You would have to take 12μm as the pixel pitch to really be on the safe side.

And an additional problems with real-life LPF is that the cutoff is not infinitely steep. If you want to suppress (nearly) all frequencies above the threshold, you will also lose lower frequencies to a lesser degree.


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## neuroanatomist (Aug 31, 2016)

midluk said:


> I think you did the factor 2 in the wrong direction. With 6 μm pixel pitch, your Nyquist limit is at 12μm. A sinusoidal signal that repeats every 12μm has its maximum and minimum 6μm apart.



Headsmack. How is a blur magnitude smaller than a pixel actually a blur?!? Thanks for the correction!


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## scyrene (Aug 31, 2016)

neuroanatomist said:


> Maiaibing said:
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> > If you use the link above to dpreview you can download and /or check out the difference of the visible lines between the 5DIV and 5DS/R. It is - extremely - easy to see that the 5DS/R has much more detail than the 5DIV. You can simply see the lines along he ruler the whole way up to 50 while the lines blur to extinction already around the 38 mark on the 5DIV test photo.
> ...



This is what I was thinking of when I asked the questions. Thanks for clearing it up! Lots of good info in this thread 



East Wind Photography said:


> I also still see a lot of confusion over the term sharpness vs detail and that may have been where i erred in my statement. All is well in the continuum.



Am I right in thinking people are using the term 'sharpness' to mean two different things - resolution of fine detail, and microcontrast at edges?


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## AlanF (Aug 31, 2016)

Scyrene, you are right that there is sloppy usage of "sharpness". I also try to separate resolution and acutance. The AA filter does two things. It lowers resolution, and conventional "sharpening" can't restore detail that is no longer there. It lowers actuance, the local contrast you mentioned, and sharpening can restore that. If I have got it wrong, please correct me.


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## Michael Clark (Sep 1, 2016)

midluk said:


> neuroanatomist said:
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> > What an AA filter does is to add blur to prevent the aliasing (e.g. moiré) caused by repeating patterns in a subject where the periodicity is approximately half that of the pixel pitch or higher (Nyquist limit). Incidentally, that's why the AA filter is also called an optical low pass filter (OLPF) – it allows frequencies lower than the cutoff to pass, while blocking (blurring out, in this case) higher frequencies. For example, if a sensor's pixel pitch is 6 µm (the 5DIII is close), then patterns that repeat every 3 µm would be at the Nyquist frequency, patterns repeating every 4 µm would be lower than the Nyquist frequency, and patterns repeating every 2µm would be above it. It's the 'at or above' that the filter is designed to reduce/eliminate.
> ...



On a typical Bayer pattern the Nyquist frequency of green is half the width of the Nyquist frequency of Red and Blue because Every 2nd sensel in each direction is green whereas only every 4th sensel in each direction is Red or Blue. After demosaicing the absolute resolution limit of a typical regular Bayer sensor works out to about 1.414x (√2) the pixel pitch.


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## Mikehit (Sep 1, 2016)

Michael Clark said:


> On a typical Bayer pattern the Nyquist frequency of green is half the width of the Nyquist frequency of Red and Blue because Every 2nd sensel in each direction is green whereas only every 4th sensel in each direction is Red or Blue. After demosaicing the absolute resolution limit of a typical regular Bayer sensor works out to about 1.414x (√2) the pixel pitch.



So if you are going to photograph a woman wearing a shawl make sure it is not a green one ?


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## jeffa4444 (Sep 1, 2016)

neuroanatomist said:


> Maiaibing said:
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> > If you use the link above to dpreview you can download and /or check out the difference of the visible lines between the 5DIV and 5DS/R. It is - extremely - easy to see that the 5DS/R has much more detail than the 5DIV. You can simply see the lines along he ruler the whole way up to 50 while the lines blur to extinction already around the 38 mark on the 5DIV test photo.
> ...


Would have preferred to see them use something like Image Engineering CIPA TE252 High Resolution Test Chart using a LE7 light source or similar and analysis software. Minimising subjectivity is the best way to derive consistent testing that my view.


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## canikon (Sep 8, 2016)

neuroanatomist said:


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> ...


This discussion is very interesting for me, I'm an early adopter of the 5D MkIII and D800 and now I am on the fence since I would really like to have a body without AA filter but the 5DSR eems to have the old chip tech with off-chip ADC converter while the 5DmarkIV seems very promising about this aspect.
Anyway, for what I know, there's a small misunderstanding about the Nyquist theorem in this reasoning, especially when you say "_What an AA filter does is to add blur to prevent the aliasing (e.g. moiré) caused by repeating patterns in a subject where the periodicity is approximately half that of the pixel pitch or higher (Nyquist limit). Incidentally, that's why the AA filter is also called an optical low pass filter (OLPF) – it allows frequencies lower than the cutoff to pass, while blocking (blurring out, in this case) higher frequencies. For example, if a sensor's pixel pitch is 6 µm (the 5DIII is close), then patterns that repeat every 3 µm would be at the Nyquist frequency, patterns repeating every 4 µm would be lower than the Nyquist frequency, and patterns repeating every 2µm would be above it. It's the 'at or above' that the filter is designed to reduce/eliminate._"
Actually I understand that the patterns that will be unable to be correctly represented will be all those with a wavelength (i.e. a spatial repeating pattern) less than DOUBLE of that of the sampling spatial distance.
To put things as simple as possible referring to your example above, with a pixel pitch of 6µm it will be feasible to represent a pattern whose "wavelength" or repeating distance is 12µm or bigger. Every pattern that repeats on the sensor in less than 12µm will cause aliasin. Obviously all this reasoning is correct if we consider only one color at time, for the RGB pattern the reasoning has to be slightly modified as someone has already pointed out.


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## Diko (Sep 8, 2016)

Act444 said:


> Not sure 100%, but judging from the samples DPR posted, there certainly appears to be a filter - perhaps even slightly stronger(?) than the one in the 5D3...
> 
> https://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=canon_eos5dmkiv&attr13_1=canon_eos5dmkiii&attr13_2=canon_eos5dsr&attr13_3=canon_eos5ds&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=800&attr16_1=800&attr16_2=800&attr16_3=800&attr171_3=off&normalization=full&widget=1&x=0.4848647313366422&y=1.0164753417379968


 Interesting. Thannks for sharing. I have checked it before, but just right now on this card I noticed the color shift.

Is it possible that _*the sharpness here is lost due to lack of contrast?*_ Could it be due to better DR?

I can see there's a color shift for certain, because I write this on a calibrated monitor. And yet the above crossed my mind...


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## neuroanatomist (Sep 8, 2016)

Diko said:


> Act444 said:
> 
> 
> > Not sure 100%, but judging from the samples DPR posted, there certainly appears to be a filter - perhaps even slightly stronger(?) than the one in the 5D3...
> ...



Most likely, it's due to the fact that they are using a beta version of Adobe software for the 5DIV images, which is not yet properly optimized for that sensor.


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## Diko (Sep 8, 2016)

neuroanatomist said:


> Most likely, it's due to the fact that they are using a beta version of Adobe software for the 5DIV images, which is not yet properly optimized for that sensor.


 Can you imagine?

All we have seen could be THAT buggy?!? Not to be excluded as a possibility. Let's hope for the best.

However I just saw this (again not for the first time) and in correlation to what we talked so far.... 

Could it be that the blurry-ness is *not *due to *AA filter*, but actually comes from the new *DPRAW*?


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## neuroanatomist (Sep 8, 2016)

Diko said:


> neuroanatomist said:
> 
> 
> > Most likely, it's due to the fact that they are using a beta version of Adobe software for the 5DIV images, which is not yet properly optimized for that sensor.
> ...



I can easily imagine it, because that's exactly what happened with the 80D. At L east DPR highlights it by coloring the info button yellow, and they go back and reprocess the images with the actual release version once it's available. 

It's not due to dual pixel RAW, because those files can only be processed using Canon's DPP.


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## Diko (Sep 8, 2016)

neuroanatomist said:


> It's not due to dual pixel RAW, because those files can only be processed using Canon's DPP.



I don't reject the other theory. But the screenshot you see is from a promotional video processed with a beta version of DPP (true), and yet one of DPRAW main features so far is exactly, perhaps selecting the better shot or readjusting the focus thanks to shifting the DoF....

What I say is: don't dismiss DPRAW theory so fast. Will wait and see, of course ;-) It could be either a bug in DPP or even firmware, or it could be "a bug that is a feature" ;-)

Of course a third option is the stupid AA filter.


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## neuroanatomist (Sep 8, 2016)

Diko said:


> neuroanatomist said:
> 
> 
> > It's not due to dual pixel RAW, because those files can only be processed using Canon's DPP.
> ...



To clarify, I was referring to the previous response where you quoted the link to the DPR comparison tool. For their comparison tool, they use Adobe Camera RAW to process images and so far, only DPP supports DPRAW images (Adobe has said they're working on it, though). Since the decision to use DPRAW has to be made before capture, the images for DPR's comparison tool would have to have been captured as regular RAW images, not DPRAW images...so DPRAW is not the explanation for 'softness' with the 5DIV in DPR's comparison tool.


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## Act444 (Sep 8, 2016)

The 5D4 image RAWs also appeared soft in DPP 4.5 once I updated and was able to bring them in, not a whole lot better than what was on DPR to begin with. Not sure what is going on other than what I've speculated earlier. However, I'm positive the cause is not DPRAW as these are normal Raw files. 

People should be getting this camera in their hands soon, so I expect a lot more follow-up re. this topic.


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