http://www.luminous-landscape.com/reviews/cameras/fuji_x100_follow_up.shtml

Since the beginning of time (or at least since the first generally available digital cameras around 1999) DSLR makers have been concerned about moire. "What's moire", you say? "I've never seen it"? Right!

The reason that you likely haven't seen moire is because your camera has a filter in front of the sensor that prevents it. How does it do this? It prevents moire by blurring the image. Yes, indeed. Your expensive camera almost certainly has a filter in front of the sensor that lowers the resolution in an attempt to prevent moire. This indeed does prevent it, but at the expense of resolution and detail.

Medium format backs typically do not have AA filters, which is one of the reasons for their superior image quality.

As I was first working with the X100 I was taken with how crisp the images were. They reminded me of these from the Leica M9. At first I simply thought that this was due to their functional similarly, but that didn't make sense. There's nothing inherent about an optical viewfinder camera that makes it sharper.

It wasn't long before I realized that it was likely that, like the M9, the X100 didn't have an AA filter (Anti-Aliasing Filter, AKA blurring filter, AKA moire remover). I figured that it shouldn't be too difficult to find an example to determine this one way or another. Right? Wrong!

The major camera makers would have you believe that the world is full of lurking examples of subjects that will jump out at you and ruin your photographs with moire. The truth of the matter is, it's very hard to find such examples when you're looking for them, let alone in day-to-day photography.

If you're a fashion photographer this may not be the case. Your world is full of man-made fabrics with very fine patterns that can "beat" with the grid frequency of your camera's sensor. For you, a Nikon, or Canon, or other DSLR with a strong AA filter is what's needed (or, lots of time in post-processing). For the rest of us? Not so much.

不太靠谱，当年富士在做S5pro的supperCCD的时候，就已经加入低通了。
要确认这个也不难，直接加个红外滤镜，测试一下曝光量和普通单反有多大差别就行了。

抱歉，看错了

[gang21 编辑于 2011-05-15 02:17]

怎么知道的？可否告知下？

是有的，而且较厚。