removing the AA filter

[Phil Indeblanc]

Hi,

The issue is always complicated by the need of sharpening. An AA-filtered image needs and can take much more sharpening than an unfiltered image.

Regarding the Foevon it would actually just make things worse. It has relatively low resolution so it really needs AA-filtering.

Best regards
Erik

Sharpening after the AA is not resolution gained or even preceived to be gained, specifically on macro work that details are all so important.

I know the res is low. I was hopping one of the big guys can break the res cap?

So anyone have a practical way to explain the reason why we can't have a DSLR without a AA filter...much like the big brothers in MF?  I know there is a lens resolution lpmm ratio that I don't know a lot about.... perhaps the spacing between photon sites and the lens resolution spcial thing a ma jig...Like someone said...Its more dangerous to know part of something, than to know nothing of it at all.

[ErikKaffehr]

Hi,

I don't see the point. The AA filter is not as much reducing resolution as reducing contrast. Sharpening increases edge contrast. With macro there are other issues, a macro lens with nominal aperture at f/8 would have a real aperture (with extension taken into account) of f/16, so diffraction can show up early. Once you stop down enough the effect of the AA-filter can be ignored.

The reason that AA-filtering is done is that the sensor cannot reproduce detail that is smaller than a pixel correctly. Lets take one of those power lines polluting the landscape. If the power line is one pixel thick and horizontal it could affect:

1 pixel
2 pixels (if shifted half a pixel)
0 pixels (if it's in between two pixels and the fill factor is low)

So it could vary in thickness, have a staircase effect or simply disappear. Now, the problem doesn't arise very often. Because:

1) Power lines are not normally one pixel wide.
2) Really good technique is needed so that the power line is imaged on a single pixel. Perfect focus, no vibration and medium aperture.

The problem goes away if we reduce pixel size so the pixels are half the size of the smallest spot the lens can reproduce.

The AA-filter is essentially a set of two beamsplitters (one horizontal and one vertical). They split the light beam to make sure that that some of the light also hits the neighboring pixels. The strength of the AA-filter is determined by it's thickness.

I don't know why they don't have AA-filters on MFDBs. One reason is probably that even if artifacting is unavoidable the artifacts are seldom obvious except as colorful moirés. For the problem to show up the feature size should be close to the pixels size.

It seems that Moirés often are a problem when shooting fabric and this is one of the reasons studio photographers want to shoot tethered. They don't want to have 200 shot's with moirés, tethered shooting allows them to discover the problem early.

To explain the problem a little bit better, look at this image taken with a Sigma DP2 (with Foevon sensor without AA-filter)

http://a.img-dpreview.com/reviews/SigmaDP2...res_ACR-002.JPG

If you look carefully you can see that the lines start to move around at about 14 (half way between 12 and 16) at 18 we have gray and at 20 we see new line structure.

If you now check a DSLR image: http://a.img-dpreview.com/reviews/SigmaDP2...330_ACR-002.JPG

You can see that all lines are continous. We se no lines wiggling around and no false contrast.

Best regards
Erik

Sharpening after the AA is not resolution gained or even preceived to be gained, specifically on macro work that details are all so important.

I know the res is low. I was hopping one of the big guys can break the res cap?

So anyone have a practical way to explain the reason why we can't have a DSLR without a AA filter...much like the big brothers in MF?  I know there is a lens resolution lpmm ratio that I don't know a lot about.... perhaps the spacing between photon sites and the lens resolution spcial thing a ma jig...Like someone said...Its more dangerous to know part of something, than to know nothing of it at all.

[Phil Indeblanc]

Hi,

I don't see the point. The AA filter is not as much reducing resolution as reducing contrast. Sharpening increases edge contrast. With macro there are other issues, a macro lens with nominal aperture at f/8 would have a real aperture (with extension taken into account) of f/16, so diffraction can show up early. Once you stop down enough the effect of the AA-filter can be ignored.


I don't know why they don't have AA-filters on MFDBs.

To explain the problem a little bit better, look at this image taken with a Sigma DP2 (with Foevon sensor without AA-filter)
http://a.img-dpreview.com/reviews/SigmaDP2...res_ACR-002.JPG
If you look carefully you can see that the lines start to move around at about 14 (half way between 12 and 16) at 18 we have gray and at 20 we see new line structure.
If you now check a DSLR image: http://a.img-dpreview.com/reviews/SigmaDP2...330_ACR-002.JPG

You can see that all lines are continous. We se no lines wiggling around and no false contrast.

Best regards
Erik

Thanks for the examples, I had to view my browser at400% to see it.
I do see the lines blurr, but I also see how fuzzy and blurred the overall image is.

If the likelyhood of 1 pixel is low, then why not make it an option?  Also, if you are not sure why the MF don't use one, then I don't think you understand it as well as well either.

The edge sharpness is only because there is a difference in pixel color.  imagine your image in various areas being smeered this way.  It creates an overall fuzzy image and I have done the side by side, and there is a sure difference. Enough for me not to want a filter on it, and take the chance to occasionally get a moire.  Why can't they make this a removable filter? perhaps one that screws into the body's lens opening.

[ErikKaffehr]

Hi,

Mamiya had it on the ZD. They had an IR filter as default and an AA filter as option.

I don't know why we have this situation where all DSLRs have AA-filtering and other cameras don't. It seems that all image processing experts on this forum have the view that AA-filtering is needed. Simultaneously, very experienced users of MFDBs state that lack of AA-filtering is an advantage.

Best regards
Erik

Thanks for the examples, I had to view my browser at400% to see it.
I do see the lines blurr, but I also see how fuzzy and blurred the overall image is.

If the likelyhood of 1 pixel is low, then why not make it an option?  Also, if you are not sure why the MF don't use one, then I don't think you understand it as well as well either.

The edge sharpness is only because there is a difference in pixel color.  imagine your image in various areas being smeered this way.  It creates an overall fuzzy image and I have done the side by side, and there is a sure difference. Enough for me not to want a filter on it, and take the chance to occasionally get a moire.  Why can't they make this a removable filter? perhaps one that screws into the body's lens opening.

[Plekto]

I can imagine building a sensor which is over sampled to the extent that the lens will always be the limiting element. Then the AA filter could be removed and the image could be resampled in the camera and then stored. The highly sampled image will have more noise at each pixel but the resampled image will have the noise level consistent with the lower sampling, just no aliasing.

The Fuji sensor attempts to do this by effectively doing a on-sensor bracket-and-blend as well as a few other neat tricks.  You get very clean images as a result.  Sure, there might be more distortion and noise, but it's very consistent and film-like in that it's hard for our eyes to spot.

BTW,
The Foveon's problem with the resolution tests isn't the aliasing.  It's that the software in the camera itself and the processing software as well are trying to obtain "resolution" where the sensor just simply doesn't have any.  It's only roughly the same resolution as APS format film - not even 35mm film quality, so they do a lot of software and hardware trickery to smear the blurry areas and make the problem of sub-standard resolution less apparent.  Up to the point where it runs out of resolution and they do these "tricks" with the data, it's superbly clean.   But ~4MP isn't good enough my anyone's standards.  Even the Fuji is barely adequate as a 35mm replacement. (most Dlabs scan at 3000X2000 pixels for 35mm film)

[Phil Indeblanc]

The Fuji sensor attempts to do this by effectively doing a on-sensor bracket-and-blend as well as a few other neat tricks.  You get very clean images as a result.  Sure, there might be more distortion and noise, but it's very consistent and film-like in that it's hard for our eyes to spot.

BTW,
The Foveon's problem with the resolution tests isn't the aliasing.  It's that the software in the camera itself and the processing software as well are trying to obtain "resolution" where the sensor just simply doesn't have any.  It's only roughly the same resolution as APS format film - not even 35mm film quality, so they do a lot of software and hardware trickery to smear the blurry areas and make the problem of sub-standard resolution less apparent.  Up to the point where it runs out of resolution and they do these "tricks" with the data, it's superbly clean.   But ~4MP isn't good enough my anyone's standards.  Even the Fuji is barely adequate as a 35mm replacement. (most Dlabs scan at 3000X2000 pixels for 35mm film)

Good info!   interesting to know the Fuji (S5?) deals with it differently.  I would be interested to know how the detail differs.

[Daniel Browning]

I don't see the point. The AA filter is not as much reducing resolution as reducing contrast. Sharpening increases edge contrast.

I agree with Erik. I'd much rather have the natural, film-like photographs that result from the use of AA filters than the digital-looking images with unnatural artifacts that you get when they're removed.

[Phil Indeblanc]

I agree with Erik. I'd much rather have the natural, film-like photographs that result from the use of AA filters than the digital-looking images with unnatural artifacts that you get when they're removed.

I was hoping to get more obective input, although I respect and understand your preference.

I find in my fine art, or street shooting work, I could care less.  But when doing a product for a client, I want to see razor sharp.  It is not in my financial interest in commercial work, to convince my clients on how technology works, and how the subconsience precieves something is "better".  If I have ruled out sharpness as a weak link in my work, I can approach the rest of my shoot day without that being in the back of my mind.

So...why MF has no AA filter, and why does the DSLR's (at least most, not including the Kodak SLRC, 14n) HAVE to have a AA filter?

[Daniel Browning]

I was hoping to get more obective input, although I respect and understand your preference.

Thanks. The objective part is easy. Removing the AA filter increases aliasing. No ifs, ands, or buts. Just a fact.

The only question is whether aliasing looks good or bad. The answer is necessarily subjective. Some people look at an aliased image and describe it as highly desirable "sharpness" and "3D" look. Others look at the same exact image and see unnatural artifacts.

So...why MF has no AA filter, and why does the DSLR's (at least most, not including the Kodak SLRC, 14n) HAVE to have a AA filter?

I think it's the same reason why MFDB have poor low light performance, low dynamic range for their size, poor sensitivity, slow frame rate, and a host of other deficiencies compared to 35mm DSLRs. Low volume. They have some great advantages too, but unfortunately not enough to stem of death of Medium Format manufacturers (from over a dozen down to just 4 now). They can't afford to do their own sensor design, so they have to buy off-the-shelf parts from Kodak and Dalsa, which have far lower performance (per area) than DSLRS and don't come with AA filters.

When MFDB are used with thin DOF, the aliasing only occurs on the plane of critical focus, such as the eyes and not the hair. When they are used with very deep DOF, diffraction reduces the aliasing.

The higher the resolution, the more likely that motion blur, lens aberrations, diffraction, and other factors will prevent fine detail (and aliasing).

Furthermore, with higher resolution, the less likely that aliasing will contaminate low spatial frequencies (only the higher ones). This means that the aliasing may not be visible in normal sized prints (e.g. magazine spread) even if it is in large ones (40x30).

There is also momentum. Some people have been practicing unsafe imaging (with no protective anti-alias filter) for so long that they have become addicted to the aliasing artifacts. What they see as "sharpness" and "3D", I see as jaggies, stair-stepping, sparkling, "snap to grid", wavy lines, bands, patterns, fringing, popping, strobing, noise, false detail, and of course moiré. You can't rip aliasing away from customers too suddenly, or they will experience extreme withdrawals. Not a good move for a market that is already shrinking.

A good OLPF is lab-grown, high-grade, ground, and polished Lithium Niobate crystal. The cost scales exponentially with area because even the tiniest defect will show up on the image, thanks to being so close to the sensor. Even though MFDB is only three times more area than 35mm, the cost can be an order of magnitude (or more) higher. More importantly, Canon/Nikon ship millions of units a year, compared to less than 6,000/year for all MFDB combined, so economies of scale is a huge factor.

[ErikKaffehr]

Hi,

Just to put things in perspective. When Canon introduced the D1s there was an article here on LL where the author stated that the cost for just the AA-filter alone would be around 2000 USD. *) The AA-filter for the Mamiya ZD did carry a price tag of 2000 USD (or more).

Moiré is a well known problem with MFDBs.

Regarding the artifacting I'd say that we look far to much at images in actual pixels. For real word use the image is always scaled, up or down. When printing the image will be dithered from low PPI to high DPI. We have little control over that process. Sharpening for print is pretty excessive as haloes are introduced to compensate for expected diffusion of ink.

Jonathan Winke, who is writing a lot on this forum, is developing a new image processing tool and is involved in some discussions about down scaling. It seems that aliasing is also problem with downscaling. It seems that the correct way of downscaling an image is to blur it a little bit, downsize and sharpen.

Best regards
Erik

*) http://www.luminous-landscape.com/reviews/...s-Pricing.shtml

"Another point to consider is that the 1Ds uses an anti-aliasing filter to reduce moire. I have spoken with some design engineers who tell me that a high quality anti-aliasing filter that size likely costs about $2,000. And, to show that there's logic to this, the optional anti-aliasing filter for the Kodak DCS 760 (a much smaller chip) retails for about $850"

Thanks. The objective part is easy. Removing the AA filter increases aliasing. No ifs, ands, or buts. Just a fact.

The only question is whether aliasing looks good or bad. The answer is necessarily subjective. Some people look at an aliased image and describe it as highly desirable "sharpness" and "3D" look. Others look at the same exact image and see unnatural artifacts.



I think it's the same reason why MFDB have poor low light performance, low dynamic range for their size, poor sensitivity, slow frame rate, and a host of other deficiencies compared to 35mm DSLRs. Low volume. They have some great advantages too, but unfortunately not enough to stem of death of Medium Format manufacturers (from over a dozen down to just 4 now). They can't afford to do their own sensor design, so they have to buy off-the-shelf parts from Kodak and Dalsa, which have far lower performance (per area) than DSLRS and don't come with AA filters.

When MFDB are used with thin DOF, the aliasing only occurs on the plane of critical focus, such as the eyes and not the hair. When they are used with very deep DOF, diffraction reduces the aliasing.

The higher the resolution, the more likely that motion blur, lens aberrations, diffraction, and other factors will prevent fine detail (and aliasing).

Furthermore, with higher resolution, the less likely that aliasing will contaminate low spatial frequencies (only the higher ones). This means that the aliasing may not be visible in normal sized prints (e.g. magazine spread) even if it is in large ones (40x30).

There is also momentum. Some people have been practicing unsafe imaging (with no protective anti-alias filter) for so long that they have become addicted to the aliasing artifacts. What they see as "sharpness" and "3D", I see as jaggies, stair-stepping, sparkling, "snap to grid", wavy lines, bands, patterns, fringing, popping, strobing, noise, false detail, and of course moiré. You can't rip aliasing away from customers too suddenly, or they will experience extreme withdrawals. Not a good move for a market that is already shrinking.

A good OLPF is lab-grown, high-grade, ground, and polished Lithium Niobate crystal. The cost scales exponentially with area because even the tiniest defect will show up on the image, thanks to being so close to the sensor. Even though MFDB is only three times more area than 35mm, the cost can be an order of magnitude (or more) higher. More importantly, Canon/Nikon ship millions of units a year, compared to less than 6,000/year for all MFDB combined, so economies of scale is a huge factor.

[georgl]

Neither AA-filtered or unfiltered bayer-sensors work well - they're compromises which became better as higher photosite densities decreased the problem.

MFDBs don't use specialized ASICs which makes them slow and less responsive - that's their only quality-related compromise caused by low production volumes. The rest is technology-related, they set other priorities (just like choosing less "transparent" but more "precise" CFAs - trading sensitivity for color reproduction).
Most DSLR-sensors are also bought by suppliers, as well as AA-filters. Dalsa and Kodak are highly experienced sensor-suppliers manufacturing state-of-the-art-technology even used in much more demanding scientific and military purposes.

Their results have to go through manual post-processing, they're slow and don't offer HD-video, but their per-pixel-IQ is unbeaten - horses for courses.

One of our members made one of the very few useful (same lens!) comparisons regarding sensor/IQ-quality of MFDBs vs. DSLR:

http://luminous-landscape.com/forum/index....showtopic=39318

Half as large photosites but comparable microcontrast (despite lower MTF from the lens at the higher frequency) and superior DR.

Lower MTF caused by the lens, AA-filter or sensor/film cannot be compensated by any post-processing.

[ErikKaffehr]

Hi,

MTF is highly sensitive to sharpening at medium frequencies. I highly recommend this article:

http://www.smt.zeiss.com/C12567A8003B8B6F/...Kurven_2_en.pdf

The article refers to a couple of images illustrating different MTFs, there are some companion pictures like this:
http://www.zeiss.de/C12567A8003B8B6F/Graph...le/Image_02.jpg

I have printed the image in A2, and read the article. It's an interesting experience.

Best regards
Erik

Neither AA-filtered or unfiltered bayer-sensors work well - they're compromises which became better as higher photosite densities decreased the problem.

MFDBs don't use specialized ASICs which makes them slow and less responsive - that's their only quality-related compromise caused by low production volumes. The rest is technology-related, they set other priorities (just like choosing less "transparent" but more "precise" CFAs - trading sensitivity for color reproduction).
Most DSLR-sensors are also bought by suppliers, as well as AA-filters. Dalsa and Kodak are highly experienced sensor-suppliers manufacturing state-of-the-art-technology even used in much more demanding scientific and military purposes.

Their results have to go through manual post-processing, they're slow and don't offer HD-video, but their per-pixel-IQ is unbeaten - horses for courses.

One of our members made one of the very few useful (same lens!) comparisons regarding sensor/IQ-quality of MFDBs vs. DSLR:

http://luminous-landscape.com/forum/index....showtopic=39318

Half as large photosites but comparable microcontrast (despite lower MTF from the lens at the higher frequency) and superior DR.

Lower MTF caused by the lens, AA-filter or sensor/film cannot be compensated by any post-processing.

[Phil Indeblanc]

Daniel or Erik...can you post an image as to what you are referring about?  (please keep them at 100% for obviouse reasons,  as I don't care to look into something beyond its ability to print or reproduce
I have been shooting with MFdB for a few years now, and have not seen or noticed the artifacts you mention.  

meanwhile, thanks for these links all, I will get busy reading them.

[Phil Indeblanc]

I have started to read the links, and after looking at the twin lens images of Zeiss post..and when I got to the few paragraphs in the intro...Are todays lens good enough for 24mp sensors....

I thought...Why don't I just conduct a test and be done with it...As the other link where Chris posted his P65 to the Niko D3. Its not a convincing test for detail res.

In my opinion, As much as I read, respect and enjoy seeing his work, I think the test is very limited for seeing detail and this limits the application of it for this discussion.  I can clearly see its value as I think his intention was more so for DR, exposure highlight and such...(at least I see it more applicable for that).  But if you look at the image and the single light source, the image is rather compressed of detail.  there is no revealing light source, only a reflective backlighting that highlights and kisses the subjects.  so contrast is very high, color saturation is low.  The yarn balls with fuzz on the table is a good area to look at, but I am not convinced as it lacks much info for such a scrutany.

So...I will conduct a test.  I will use the same lens, on the same stand, fixed, and only swap the camera bodies. I will use a subject with detail, and light it with 2 or 3 fixed heads.  I will stop the lens down to  8, 11 and 22 as I noticed the Leica I have can do 22 before the light starts edging on the blades and defracts.. Does anyone want to ask or suggest anything more before I do this test, or confirm some obvious bits of info that might be overlooked?
Even a subject matter?  I don't want to do the test and then have something I left out.


I will look over and post the images.  Maybe you eagle eyes of jags and artifacts can point things out.

btw, have any of you done this already?....feel free to post.

[Daniel Browning]

Daniel or Erik...can you post an image as to what you are referring about?

Sure thing. The differences are sometimes very subtle. It's a good idea to first examine an image where the aliasing is very obvious and pronounced. Here is one such demonstration: the first image has lots of aliasing, the second has very little:





I suggest opening them in browser tabs for A/B comparison. Here are a few examples of what is different:

• Speckling in the hair (not there in real life).
• Individual hairs of stubble (they should be too small to see).
• Ear is jagged.
• Catchlight zigzags

Those are examples of the kinds of artifacts that make aliased images look fake and unnatural to me.

[ErikKaffehr]

Hi,

I would be very, very, very surprised if you'd need to stop down to f/22 for diffraction. Essentially all lenses start to show diffraction past f/8. Your lenses should probably reach maximum performance at f/4.

The measurement I show below was taken on a Minolta 80-200/2.8 APO zoom, it's quite obvious that maximum performance is reached around f/8. The factor that limits performance on lenses is diffraction. Essentially all aberrations except lateral chroma and diffraction increase with aperture.

http://83.177.178.7/ekr/images/stories/difractionlimit.gif

Admittedly, the loss of sharpness to diffraction is not easy to see, but as you can see in the figure above, you are loosing half of the resolution at f/22. This essentially means that we turned that 10 MPixel APS-C camera in a 2.5 MPixel APS-C camera.

A major factor is of course focusing. Achieving correct focus can be very hard. Lloyd Chambers has reported some issues about focusing the Leica M9 on his pay site. Erwin Puts considers a viewfinder loupe essential on the M9 for correctly focusing longer lenses. On DSLRs the best way of achieving correct focus is "live view".

And don't forget AA-filtered images need significant sharpening, very high amount at very low radius.

In my view flowers are pretty good natural test subjects. Using a Dollar bill is also quite nice,

like this one: http://www.luminous-landscape.com/images-b...est%20Image.jpg

from this test: http://www.luminous-landscape.com/essays/back-testing.shtml

I'd shoot the Dollar bill in half the scale because I feel it lack fine enough detail in the original tests. The Dollar bill is nice because many of us happen to have some around.

I would also try some focus variations. I'm using an RRS MPR rail to achieve that, keeping focus and shifting camera back an forth.

Check here: http://www.slrgear.com/articles/focus/focus.htm

and perhaps also this:

http://www.imx.nl/photo/leica/camera/page155/m9part2.html


All that said I'm looking forward to your findings!

Best regards
Erik

I have started to read the links, and after looking at the twin lens images of Zeiss post..and when I got to the few paragraphs in the intro...Are todays lens good enough for 24mp sensors....

I thought...Why don't I just conduct a test and be done with it...As the other link where Chris posted his P65 to the Niko D3. Its not a convincing test for detail res.

In my opinion, As much as I read, respect and enjoy seeing his work, I think the test is very limited for seeing detail and this limits the application of it for this discussion.  I can clearly see its value as I think his intention was more so for DR, exposure highlight and such...(at least I see it more applicable for that).  But if you look at the image and the single light source, the image is rather compressed of detail.  there is no revealing light source, only a reflective backlighting that highlights and kisses the subjects.  so contrast is very high, color saturation is low.  The yarn balls with fuzz on the table is a good area to look at, but I am not convinced as it lacks much info for such a scrutany.

So...I will conduct a test.  I will use the same lens, on the same stand, fixed, and only swap the camera bodies. I will use a subject with detail, and light it with 2 or 3 fixed heads.  I will stop the lens down to  8, 11 and 22 as I noticed the Leica I have can do 22 before the light starts edging on the blades and defracts.. Does anyone want to ask or suggest anything more before I do this test, or confirm some obvious bits of info that might be overlooked?
Even a subject matter?  I don't want to do the test and then have something I left out.


I will look over and post the images.  Maybe you eagle eyes of jags and artifacts can point things out.

btw, have any of you done this already?....feel free to post.

[Plekto]

Good info!   interesting to know the Fuji (S5?) deals with it differently.  I would be interested to know how the detail differs.

The F5 was the old technology.  The new uses a similar technology but they also have arranged the (sub)pixels in a diagonal grid and also do some fancy binning as well before the bracketing and blending is applied.

Because our eyes don't track diagonal displacement as easily and they can arrange the sensor in effectively a solid stacked array(as opposed to a triangle type formation in a Bayer sensor) - just on a slightly tighter diagonal.  A typical Bayer sensor suffers a roughly .6-.7 efficiency ratio in each dimension compared to film's real pixels at each location.  The Fuji, with the blending applied, though, it creates a .9 or better ratio.  It's close but roughly 1MP short of 35mm scanned film.  Still, to do the same with a Bayer sensor, you need a whopping ~16MP due to the efficiency losses.  And that creates a lot of artifacts and errors in the image that must either be downsampled or adjusted with various hardware and software trickery.  The software is great at what it does lately, but it's really fancy kludging.  Bayer sensors have issues that can't be worked around past what we currently see with the D3x and similar cameras.   Something new is required at this point to make any significant gain in image quality.

http://www.fujifilm.com/products/digital_c...s5pro/features/
This is the older B&B technology and it works very very well.

http://www.fujifilm.com/products/digital_c...es/page_02.html
This is the new technology which they unfortunately aren't putting in a DSLR body or making higher resolution.  The three modes are high resolution which is standard DSLR and useless, the HDR mode, which is also no better than other sensors, and the HQ mode which is what should be used nearly all the time as default - because it gives you the clean look that you want.  But you do have to apparently defeat the on-board AI that wants to select what it thinks is best and just use this mode.

Huge pain.  I hate it when electronics try to out-think you.

Of course, 6MP in HQ mode also limits the resolution of fine details too greatly.  That's the real issue with the Foveon and Fuji sensors.  Unlike the D3x which is approaching the limits of the optics in fine details, they are only halfway there.  If that.

It's so close, but not in a proper DSLR type package(WHY???) and about half the MP it needs to be(12MP with this sensor would flat out punk everything short of a DB, yet Fuji doesn't seem to want to go there for some odd reason)  And Sigma has done zilch with their sensor as well.

[ErikKaffehr]

Hi,

I have not done any testing on AA-filter less cameras as I don't have any.

I have done some testing 6x7 film against digital. Whatever your results are someone is sure to complain. In my view the kind of testing to do can be valuable to:

- Potential M9 buyers
- Any one considering his camera for AA-filter removal

It may also help to increase our understanding of the issues at hand.

But, someone will always find some error in your testing. Be prepared for some "flak".

Best regards
Erik

I have started to read the links, and after looking at the twin lens images of Zeiss post..and when I got to the few paragraphs in the intro...Are todays lens good enough for 24mp sensors....

I thought...Why don't I just conduct a test and be done with it...As the other link where Chris posted his P65 to the Niko D3. Its not a convincing test for detail res.

In my opinion, As much as I read, respect and enjoy seeing his work, I think the test is very limited for seeing detail and this limits the application of it for this discussion.  I can clearly see its value as I think his intention was more so for DR, exposure highlight and such...(at least I see it more applicable for that).  But if you look at the image and the single light source, the image is rather compressed of detail.  there is no revealing light source, only a reflective backlighting that highlights and kisses the subjects.  so contrast is very high, color saturation is low.  The yarn balls with fuzz on the table is a good area to look at, but I am not convinced as it lacks much info for such a scrutany.

So...I will conduct a test.  I will use the same lens, on the same stand, fixed, and only swap the camera bodies. I will use a subject with detail, and light it with 2 or 3 fixed heads.  I will stop the lens down to  8, 11 and 22 as I noticed the Leica I have can do 22 before the light starts edging on the blades and defracts.. Does anyone want to ask or suggest anything more before I do this test, or confirm some obvious bits of info that might be overlooked?
Even a subject matter?  I don't want to do the test and then have something I left out.


I will look over and post the images.  Maybe you eagle eyes of jags and artifacts can point things out.

btw, have any of you done this already?....feel free to post.

[Phil Indeblanc]

Sure thing. The differences are sometimes very subtle. It's a good idea to first examine an image where the aliasing is very obvious and pronounced. Here is one such demonstration: the first image has lots of aliasing, the second has very little:





I suggest opening them in browser tabs for A/B comparison. Here are a few examples of what is different:

• Speckling in the hair (not there in real life).
• Individual hairs of stubble (they should be too small to see).
• Ear is jagged.
• Catchlight zigzags

Those are examples of the kinds of artifacts that make aliased images look fake and unnatural to me.

I see exactly what you see here, and that is horrible.

I have not had 1 image with this artifact in my years of using a AA free MFdB.  Nor have I seen this in using my Kodak SLRc...which I think has issues in areas with color.  I am regularly opening these files in 400 or more % as I retouch my own work, and this is NEVER been something I have seen.  This looks like JPEG down compression artifacts.

Maybe you are referring to some other format besides RAW?  Or perhaps there is some lens to sensor relation, but I doubt it, as I have used 16 to 400mm of just about anything in between.

[Phil Indeblanc]

Hi,

I would be very, very, very surprised if you'd need to stop down to f/22 for diffraction. Essentially all lenses start to show diffraction past f/8. Your lenses should probably reach maximum performance at f/4.

The measurement I show below was taken on a Minolta 80-200/2.8 APO zoom, it's quite obvious that maximum performance is reached around f/8. The factor that limits performance on lenses is diffraction. Essentially all aberrations except lateral chroma and diffraction increase with aperture.

http://83.177.178.7/ekr/images/stories/difractionlimit.gif

Admittedly, the loss of sharpness to diffraction is not easy to see, but as you can see in the figure above, you are loosing half of the resolution at f/22. This essentially means that we turned that 10 MPixel APS-C camera in a 2.5 MPixel APS-C camera.

A major factor is of course focusing. Achieving correct focus can be very hard. Lloyd Chambers has reported some issues about focusing the Leica M9 on his pay site. Erwin Puts considers a viewfinder loupe essential on the M9 for correctly focusing longer lenses. On DSLRs the best way of achieving correct focus is "live view".

And don't forget AA-filtered images need significant sharpening, very high amount at very low radius.

In my view flowers are pretty good natural test subjects. Using a Dollar bill is also quite nice,

like this one: http://www.luminous-landscape.com/images-b...est%20Image.jpg

from this test: http://www.luminous-landscape.com/essays/back-testing.shtml

I'd shoot the Dollar bill in half the scale because I feel it lack fine enough detail in the original tests. The Dollar bill is nice because many of us happen to have some around.

I would also try some focus variations. I'm using an RRS MPR rail to achieve that, keeping focus and shifting camera back an forth.

Check here: http://www.slrgear.com/articles/focus/focus.htm

and perhaps also this:

http://www.imx.nl/photo/leica/camera/page155/m9part2.html


All that said I'm looking forward to your findings!

Best regards
Erik

Hi Erik,

I will properly focus both using the same detail area as referrence.
I think different lens combo will have difference deffraction points.  But I will do it with your F4, as well as a couple other F stops.
I will use the lens mount on to the Foba studio stand that doesnt budge.  the only moving part will be the body.
Money is good, glass, metals, and some fuzzy subject.  I am not sure about flowers as they are organic and perhaps if I get close enough to see the veiny cell seperatation...but I think I can manage a leaf.branch without going to the florist.  

***I want to evaluate the images at there RAW sharpness, but I am willing to sharpen them equally, as it defeats the purpose of the test to sharpen one file more than the other.
My point is to get the best file to start work from...Not to massage the best file.