AA-filtering CCD and CMOS

[pcunite]

As for the question asked – if AA filters are so limiting, why do smart companies like Nikon and Canon use them? I would conversely ask, if AA filters are such a problem, why do smart companies like Phase One and Hasselblad and Leica not use them? Clearly designers and engineers make design choices based on what they'd like their equipment to accomplish. We as consumers do similarly. We each have different criteria and needs, not to mention budgets.

The discussions of theory are fine, and I enjoy reading them. But, just as in the world of audio I trust my ears over measurements, in photography I trust my eyes above all else, even if what they are seeing can be described as an illusion.

This is why some people prefer over-saturated and warmer images while others don't. If I had spent $30K + on a digital back I can assure you I would prefer it's results as well. I think that photographers are too emotional to ever reach any conclusion on which system is better for their needs.

[ErikKaffehr]

Hi,

Sorry for the term mush, may be my english. I mean a region without resolved detail.

I include the region which contains artifacts in my view: [attachment=17192:aliasing.jpg]

Seen as discontinous hairs and brightness variations along strains.

According to imaging theory there should be aliasing artifacts if the lens resolves above the Nyquist limit, so it just may prove that you have a good lens and technique. I won't argue that they are harmful.

Best regards
Erik

limited DOF.  The photo was made with a 280mm lens @ f/4 and about 3 meters distance.




can you point these out?  With extreme pixel-peeping there are some whiskers that show stair-stepping but this is not evident in a large print.  Many hairs are crossing over other hairs, is this what you're seeing?



I'm not sure which area you're referring to.  Mush isn't an aliasing artifact.

[jing q]

This is why some people prefer over-saturated and warmer images while others don't. If I had spent $30K + on a digital back I can assure you I would prefer it's results as well. I think that photographers are too emotional to ever reach any conclusion on which system is better for their needs.

are you saying that michael is giving his opinion as such because he spent $30k on the camera?
actually all you need to do is get a kodak proback for dirt cheap and try it out and see the difference vs a 5D Mk II

[BernardLanguillier]

The point being that while the A900 at low ISOs, and when used with Zeiss lenses, is as good as any DSLR on the market, the M9 using Leica glass just looks superior to my eyes. There's a palpable three dimenionality to the images that's hard to put into words, but is akin to the sweetness of a tube amp over a transistor amp. (Pure Class A over Class A/B).

Michael,

Allow me to disagree with your A900 comment. Not all DSLR are equal. They may appear close compared to the quality of a P65+, but important differences exist in detail and DR, even at equal pixel count.

I have never seen any A900 image getting close to the sharpness shown in the file below for instance. To my eyes, this is as detailed (and aliased for that matter) as any AA filter less file.

Original image reduced to 2000 pixel for posting purpose:



100% crop of the central part of the image:



And for reference, the final 150 megapixel pano using this image...



Cheers,
Bernard

[pcunite]

are you saying that michael is giving his opinion as such because he spent $30k on the camera?
actually all you need to do is get a kodak proback for dirt cheap and try it out and see the difference vs a 5D Mk II

I can clearly seen the benefits of MFD at low ISO and large viewing sizes. But to say that MFD is also superior in other ways (such as 8x10 size) is tempting after you have spent $30K. Michael is well respected for hosting this site and giving us his opinions. I don't know the limit of 35mm as I have never printed beyond 16x24 (it was from a 10mp file and I did not really like it personally, the customer loved it) but I can say that MFD is not the best for every situation, micro contrast or not. It is the $30K price that causes one to see something special in a small print. That is all I am saying.

[tho_mas]

To my eyes, this is as detailed (and aliased for that matter) as any AA filter less file.

to my eyes it is not.
But what does your view or my view proof? ... unless you shoot the same motif side by side with and without AA filter sensors and (roughly) comparable lenses?

[michael]

This is why some people prefer over-saturated and warmer images while others don't. If I had spent $30K + on a digital back I can assure you I would prefer it's results as well. I think that photographers are too emotional to ever reach any conclusion on which system is better for their needs.

You are presuming that I appreciate a P65+ back (or an M9 for that matter) because of how much I spent on it. That is erroneous.

Indeed it is just the opposite. I spend the money because I can see the difference that this level of gear provides for the type of shooting that I do and the size of prints that I make, exhibit and sell.

I am subject to self delusion and rationalization as much as most people, but not when it comes to spending that kind of money. I am fortunate in that I get to field test all sorts of high end gear. No guess work, no buyers remorse (at least not often), and always based on what I can see.

Others may differ with my opinions, but I put my money where my mouth is – or at least where my eyes suggest they should be.

Michael

[bjanes]

As for the question asked – if AA filters are so limiting, why do smart companies like Nikon and Canon use them? I would conversely ask, if AA filters are such a problem, why do smart companies like Phase One and Hasselblad and Leica not use them? Clearly designers and engineers make design choices based on what they'd like their equipment to accomplish. We as consumers do similarly. We each have different criteria and needs, not to mention budgets.

Michael

There may be other considerations as to why MFDBs and Leicas lack a blur filter. As pointed out elsewhere, a blur filter for a MFDB would be quite expensive to produce, since the cost increases exponentially with the sensor size. Also, MDFBs are very high resolution, and alaising could be downsized out of existence when the print is made. The Leica is limited by a short back focal distance (see Erwin Puts) which limits what kind of filter can be placed in front of the sensor. In the M8 they were not even to implement an IR filter. Erwin states "The M9 filter thickness is now 0.8mm as compared to 0.5mm for the M8 and more than 2mm for the D3x". A 2mm filter could cause severe problems with the short back focal distance of the Leicas.

[pcunite]

Others may differ with my opinions, but I put my money where my mouth is – or at least where my eyes suggest they should be.

Thank you for your thoughts Michael.

[jing q]

I can clearly seen the benefits of MFD at low ISO and large viewing sizes. But to say that MFD is also superior in other ways (such as 8x10 size) is tempting after you have spent $30K. Michael is well respected for hosting this site and giving us his opinions. I don't know the limit of 35mm as I have never printed beyond 16x24 (it was from a 10mp file and I did not really like it personally, the customer loved it) but I can say that MFD is not the best for every situation, micro contrast or not. It is the $30K price that causes one to see something special in a small print. That is all I am saying.

I think he stated that he was hard pressed to tell a difference in cameras until a larger size print was made...

[Daniel Browning]

After all the technical talk, I still don't see your point or why aliasing is such a big issue.
Perhaps that's where the problem lies, a lot of people who use AA filterless images actually are not bothered by the aliasing?

Yes, that is my best guess. What to me is aliasing is to another person the ideal microcontrast.

Granted, there are times when it is visible (esp in certain highlights)
but from my personal experience no matter how much I sharpen images I still get a slightly mushy and blurred effect with DSLRs with their AA filters.
And the mushiness/blurring is MUCH more disturbing to me than any aliasing.

I can understand your point of view. For me, sharpening compensates for the OLPF very well, but it leaves me between a rock and a hard place when noise is high.

However, even if you use no sharpening whatsoever, you can completely remove the effects of the OLPF by simply buying a sensor with 1.3X more linear resolution than you need. If you need a sharp 12 MP, buy 20 MP. Then you get the rid of the mushy/blurred effect without sharpening and without aliasing. However, if aliasing is the very thing that you are trying to get, then you would not like it.

which goes back to your explanation of 3 pixel natural edge vs 2 pixel unnatural edge
I actually don't find 2 pixel edges unnatural. I actually think that's what makes lines so much more defined.

I think that helps explain the difference in perception. When you look at Image A/B comparsion from my earlier post, do you find Image A to be more pleasing?

Another thing is that how visible are aliasing effects when files are actually printed?

If the smallest details are visible, then so too is the aliasing. I see a ton of aliasing artifacts in prints all the time, but they're usually caused by the downsampling during post, not the camera itself. Photoshop does poorly with large resampling ratios, such as taking 21 MP down to 2 MP for a 4x6. Lightroom 2.0 was slightly better, and later in 2.x (I think) they improved the downsampling algorithm further, but it still results in far too much aliasing for my taste. Qimage, irfanview, and ImageMagick are much better.

So, pick your artifacts: mush or aliasing.

I pick mush.

As for artifacting, well, try as I might, on prints and at 300% on screen, I just don't see it, as long as sharpening is carefully and properly done. If I'm confusing artifacting with resolution, then long live the revolution.

One man's ugly artifacts are another man's fine detail. I think it's a difference in taste/perception.

I can clearly seen the benefits of MFD at low ISO and large viewing sizes. But to say that MFD is also superior in other ways (such as 8x10 size)...

I kindly disagree. There are many circumstances when a MF back is superior even at 8x10 size. For example, let's say the viewer's CoC is small enough to see 1000 LP/PH in the 8x10. On 35mm, that corresponds to 42 lp/mm. But on Medium Format the same print size is only 26 lp/mm due to smaller reproduction magnification. Many wide angle 35mm lenses are not able to provide the same level of aberration correction at much higher spatial frequencies, which is clearly reflected in their MTF charts. Worse still, they must operate at wider f-numbers to get the same depth of field and diffraction.

[BernardLanguillier]

to my eyes it is not.
But what does your view or my view proof? ... unless you shoot the same motif side by side with and without AA filter sensors and (roughly) comparable lenses?

True, but this was not my main point anyway.

As far as this M9 vs DSLR topic is concerned, there is at least one person who did the test on both a D3x and M9, and his conclusion are different from Michael's regarding the amount of detail captured (http://www.imx.nl/photo/leica/camera/page155/m9part2.html).

Citing him:

"We may infer from these graphs that the Nikon images benefit more from the post processing, but get that now familiar (and not always pleaseant) digital look, where the Leica images are more closely related to the classical film look and here the sharpening effect is less pronounced. The Leica M9 is quite close to The Nikon D3x in definition and resolution, but Nikon photographers do not need to fear that the M9 will dethrone the D3x as the reference camera for state of the art quality. Stunning as the M9 pictures are, they must be put in context and then the Nikon D3x images are just better. "

Since Michael did not test the D3x against the M9 (Michael doesn't own a D3x as far as I know), but based his comment on a generic belief that all DSLRs are basically the same (conclusion being based on a limited amount of D3x usage), I tend to trust Erwin's conclusions more on this particular point, especially knowing that he is known to be very close to Leica.

Cheers,
Bernard

[tho_mas]

As far as this M9 vs DSLR topic is concerned, there is at least one person who did the test on both a D3x and M9, and his conclusion are different from Michael's regarding the amount of detail captured

But Michael is not referring to "details captured" only as it would be boring anyhow:

a combination of resolution, clarity, accutance and modeling. Much of this may well be caused by the Leica lenses (...)
There's a palpable three dimenionality to the images that's hard to put into words

This notion is brought up quite often. And indeed one can't disprove it with pure measurement of data.

[Daniel Browning]

But Michael is not referring to "details captured" only as it would be boring anyhow:
This notion is brought up quite often. And indeed one can't disprove it with pure measurement of data.

All the talk I've ever heard about three dimensionality can be attributed to one or more of the following:

• Wide angle
• Thin DOF
• Aliasing
• Contrast

For example, MFDB has exactly those factors. If you take them away, you take away the "3D-ness". For example, shoot telephoto, deep DOF, with a lowcon filter (or junky lens) to remove contrast, and you'll end up with a non-3D photo from a MFDB.

In the case of the Leica, the rangefinder advantage is especially strong with wide angles and thin DOF. They also provide good contrast and strong aliasing.

Foveon, too, was described by many as 3D. In that case it was just the aliasing.

[BernardLanguillier]

But Michael is not referring to "details captured" only as it would be boring anyhow:
This notion is brought up quite often. And indeed one can't disprove it with pure measurement of data.

It does read like a Stereophile review, doesn't it?

Cheers,
Bernard

[tho_mas]

It does read like a Stereophile review, doesn't it?

well, maybe :-)
Everyone has his own experiences and value certain properties over others ... and there's nothing wrong with that.

[bjanes]

Trying to bring things back to practical reality...

Then there's the Leica M9. Visibly superior to the A900, even on small prints. This is a combination of resolution, clarity, accutance and modeling. Much of this may well be caused by the Leica lenses. The point being that while the A900 at low ISOs, and when used with Zeiss lenses, is as good as any DSLR on the market, the M9 using Leica glass just looks superior to my eyes. There's a palpable three dimenionality to the images that's hard to put into words, but is akin to the sweetness of a tube amp over a transistor amp. (Pure Class A over Class A/B).

It has been obvious for years that high performance and small volume in high tech are incompatible requirements in the mid/long run.

The way nuforce is totally trouncing high end hifi equipment costing 5 or 10 times more is yet another example in the supposedely different high end hifi world too.

Cheers,
Bernard

It does read like a Stereophile review, doesn't it?

Cheers,
Bernard

Good heavens, that nuforce appears to be solid state .  Could it possibly best a tube amplifier?

[michael]

Bernard,

I used to have a lot of respect for Erwin's lens-related work, but his recent digital camera reports are showing cracks in his methodology and understanding. Doing his tests using in-camera JPGs, for example.

I have no desire to knock him here, but I have heard from more than a couple of knowledgeable tech journalists recently who are privately musing that everything is not all as it should be with his recent work on cameras and sensors as opposed to lenses.

In other words, I disagree with Erwin's M9 results based on my own tests, and while I haven't done the D3x comparison I have done it with the A900 and the 1Ds MKIII, which others have measured as having comparable resolution to the D3x. The D3x's forte, as you know, is its high ISO capability, and not any particular lead in the resolution department. And I have no need to quibble over Nikon glass vs. Zeiss. The best of both are comparable, and probably differ more in individual samples that in type.

Michael

[BernardLanguillier]

Good heavens, that nuforce appears to be solid state .  Could it possibly best a tube amplifier?

I know... either way, my personnal preference remains to have my own private orchestra playing on demand in the kiosk, you can't beat that kind of DR and even nuforce can't factor in the influence of the birds singing in the background.

Cheers,
Bernard

[BernardLanguillier]

In other words, I disagree with Erwin's M9 results based on my own tests, and while I haven't done the D3x comparison I have done it with the A900 and the 1Ds MKIII, which others have measured as having comparable resolution to the D3x. The D3x's forte, as you know, is its high ISO capability, and not any particular lead in the resolution department. And I have no need to quibble over Nikon glass vs. Zeiss. The best of both are comparable, and probably differ more in individual samples that in type.

Michael,

Thanks for the feedback.

Having not yet used a M9 myself, I cannot comment further on the comparison between these 2. I would be very surprised if typical usage of the M9 resulted in critically focused files most of the time anyway, so this is very theoretical I believe.

As far as the D3x vs the other DSLRs goes, the key is that the amount of sharpening that a file can take at low ISO is directly impacted by the level of noise present in the file. This is where the main strenght of the D3x relative to the competition, larger DR and lower noise in low ISO files, plays a major role and makes it possible to extract significantly more detail with proper sharpening (this being further facilitated by the weaker AA filter the sensor is equiped with). I guess that the example I posted above speaks for itself.

This conclusion is coming from shooting tens of thousands of images with the D3x, mostly with the best Zeiss glass available in Nikon mount.

I guess that we'll have to agree to disagree on this point.

Cheers,
Bernard