How much does an AA filter affect image quality?

When Canon announced their new 1DsIII a discussion was started on how the lenses were going to limit the resolution of the images (i.e. Canon didn't have lenses good enough for the sensor on this new camera). I mentioned that until the anti-aliasing filter (AA) was removed the lenses wouldn't be the limiting factor.

I found this report on a Nikon D200 comparison with it's AA filter and without it. Going in I realized that the filter would reduce resolution, but it also hazed the image and reduced color fidelity too. But to be honest, I never thought it would be by this much.

Check it out and lets hope the camera manufactures start making cameras without these filters soon.

That's downright scary!

That is a big difference.

Turns out this is a very complex subject, and moire removal is a lot harder to do than to make the image appear sharper with post processing. Otherwise the camera manufacturers would have done it Nikon has been moving more and more to a less aggressive AA filter (ie in camera images are sharper) while Canon has been more aggressive with the AA filter (less moire but not as sharp).

I believe the Leica M8 does not have an AA filter and the Kodak FF DSLR did not as well.

Paul, this is definitely a complex subject and I'm sure they have their reasons, but for landscape photogs it's probably not necessary in 99% of the shots and as the article said this filter affects every shot regardless if moire would be an issue or not. With PS it's easy to clone just about anything out, so moire just isn't an issue any longer (unless you photograph CEO's with herringbone suits all day ).

I'm not saying it's right or wrong to have this filter, but it's amazing how much it cuts down on the resolution. I'd say this however; we have a long way to go before the lenses are limiting things as much as these filters.

Interesting thread. A couple of months ago I had my Digital Rebel converted to IR and I've noticed the images from this camera are now really sharp. I thought it mostly had to do with the fact that IR light can cut through haze, but I asked Life Pixel (they converted the camera) and they told me that the AA filter is removed during conversion. I agree with Craig that for landscape photography, the AA may not be needed. I shot this one with the converted Rebel -
http://www.photoportfolios.net/portfolio/pf.cgi?a=vp&pr=59226&b=up&st=1&la=3&ph=1&sid=4020&pi=PEWEG&u=4020

If someone finds out how to remove a Canon AA filter, please let me know. :) Enlightening to say the least.