p.1 #1 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
Partly in response to the D800/D800E (the latter of which I'm really digging, myself) we just posted a new article that focuses on (no pun intended) exactly what the AA filter does and how it affects images by comparing two similarly-specced cameras and lenses. Might be interesting for some:
It compares a Canon 1D Mark IIn against a Leica M8, which are similar in spec. One important difference being the AA filter. The lenses used were the 50L and 50 Lux (at f/5.6). This comparison is interesting on its own.
Maybe we'll add an "Advanced Discussion" section if there's enough interest. Of course, we'll add to and update the article, as with all of them as well.
p.1 #2 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
I find this statement a bit dubious: "Another way to look at it is most consumer cameras have the filter while more prosumer (or pro) level cameras lean towards not having it."
No professional DSLR from Canon/Nikon has been without an AA filter so far. If the D800E can be called a professional camera, it's the first one with a filter that doesn't do AA. Leica M cameras aren't particularly aimed at professionals either, so that means you're left with medium format cameras, and I don't think it's an established fact that they don't have AA filters because it's so beneficial for IQ.
Tip: include a sample image of moiré to illustrate the phenomenon.
p.1 #3 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
Okay, that sentence might be better worded, as it bothered me a little too. It's arguably a more "pro" rather than "prosumer" feature. As for whether or not the M8/M9 are "aimed at pros" or not is a debate for another time... Medium format backs either have them or don't and some feature a removable AA filter. It's most definitely for IQ purposes and there's no denying that MFDB are "pro."
You're right about the sample image(s); I'll have to add a few. I didn't have any handy at the time.
p.1 #5 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
You also didn't mention the point that Leica doesn't use an AA filter and the thin IR/UV filter in order to minimize IQ degradation due to the extreme ray incidence angles of rangefinder lenses. The blurring due to the AA filter in itself wouldn't really be a problem if the exit pupil of (esp. wide angle) rangefinder lenses wasn't so close to the sensor. So effectively, you're explaining what an AA filter does, but not what is probably the most important reason why Leica isn't using one.
p.1 #7 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
DoubleNegative wrote:
Hmm, interesting point - and certainly worth getting into. At first I didn't want to get too technical with the article but it seems inevitable.
You might wish to cite the Zeiss white paper which discusses the phenomena - the AA filter in combination with rangefinder glass with an exit pupil close to the sensor, more notable as the focal length leans to wide angle lenses - works to create astigmatism which shows up as edge and corner detail destruction / softness.
There's been a fulsome discussion of AA vs no AA recently in the "Still no love for Ricoh GXR thread", starting at about page 19:
p.1 #8 · Anti-Aliasing Filter Primer (or 50L vs 50 Lux)
Yes, it's pretty a complex subject. I'm no expert on this, but I find it interesting and what I wrote above is what I've picked up from a couple of forum members who are active in the field of digital sensors engineering.
The Ricoh GXR M module is designed to work with Leica M lenses and also doesn't have an AA filter, and it demonstrably performs better (esp. in the corners) than these lenses do on Sony NEX, for instance.
