George,
You made a post last week, but I didn't notice it until today.
@Daniel Browning
The "look" of moire has definitely changed with the various sensor-generations (with increasing fill-rate) but alaising itself appears nevertheless and never seemed to influenced the choice of AA-filter vs. unfiltered!?
I don't understand if you're rephrasing my statement in the form of a question or making your own statement in the form of a comment, but perhaps it will help if I just add a clarification. My position is that aliasing characteristics are dependent on the optical fill factor (with microlenses considered), not the electronic fill factor (of the bare sensor with no microlenses). I think that microlenses have given CMOS optical fill factors comparable to CCD for at least several years; therefore it has not influenced the choice to use OLPF or not.
AA-filters are needed if you have to avoid moire at any cost. Press-photographers usually don't have the time to post-process the images to remove moire - they rather live the loss of fine detail/contrast.
First of all, there is no post-processing that can truly remove moire. The best software (C1P IMHO) can only smear the moire into the surrounding detail.
Second, moire is only the worst and most offensive aliasing artifact. But there are many other aliasing artifacts that I find displeasing and unnatural, including jaggies, stair-stepping, sparkling, "snap to grid", wavy lines, bands, fringing, popping, strobing, noise, and false detail. These, too, are impossible to remove through any automated or semi-automated software process.
In real life, when you pour two liters of water into a one liter container, water spills out and makes a mess. But camera design is different: when you pour two liters of water into a one liter container, the water folds back on itself and corrupts the entire container. The amount of water is the level detail (spatial frequency), and the volume of the container is the number of megapixels in the camera. Aliasing is the corruption. Anti-aliasing filters reduce detail down to a level that can fit within the pixel resolution.
But of course, that's just me personally. Two people can look at the exact same image and each see something different. Take an aliased image for example. Where one sees overly harsh and sudden transitions from black to white in just 2 pixels, another sees microcontrast. Where one gets the impression of fakeness, another gets the feeling of sharpness. Where one is jarred by the conformation of small details into a slightly different location than they exist in nature, another is awestruck by the high acuity.
Same thing with anti-aliased images. Where one sees slow, smooth, and careful transitions from black to white, over 3 or more pixels, another sees mushy detail. One gets the impression of natural, life-like renditions, another gets the feeling of haze and low contrast.
So you may percieve an unfiltered image as having high microcontrast, sharpness, and acuity; while I see the same one as harsh and unnatural. The OLPF'd images you perceive as mushy, haze, lowcon images are, to me, smooth and natural. So it would be difficult for us to come to agreement on how big of an issue aliasing is.
I think part of the reason why some manufacturers (e.g. MFDB) exclude OLPF is cost. 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.
If camera manufacturers were shrewd enough, they would stop wasting so much money and effort to fight it. It's not like they get appreciated for it, they're more often lambasted (IMHO). I think the market of people that like aliasing is large enough. But since I happen to belong to the smaller part that prefers anti-aliased images, I'm glad they haven't (yet) given up on the expensive AA filters, and hope they never do. (At least until we start hitting diffraction cutoff frequencies at faster f-numbers.)
But the basics of alaising and AA-filters remain unchanged, moire doesn't destroy detail and AA-filters don't preserve it.
I kindly disagree. For my taste, the AA-filtered image is better, because although the detail is low contrast, at least it's real. The detail in an unfiltered image is very high contrast, but it's false detail. But I understand that others have different personal preferences.