Kodak is not including an AA filter in the DCS 14n to reduce cost and because they feel that due to the extreemly high resolution of the system users won't encounter it too often.
Exactly! Kodak feel that due to the extremely high resolution of the system (but more specifically, the high resolution of the sensor) users won't encounter moire and aliasing artifacts too often. That's my point.
As I see it, the lens itself can be considered as a low pass filter, in fact, a variable low pass filter. You can increase the efficacy (or threshold) of the filter by stopping down below F8 or F11. But, if you have to use an AA filter in addition to the 'natural' filtering process of the lens, then there HAS to be room for improvement of the sensor - ie. a higher resolving sensor.
The way you've described this situation, simple minded people like myself might get the impression that you're saying lower resolution sensors like the D30 and Contax N1 don't need AA filters and that the extremely high resolution sensors of many 3 and 4MP point-and-shoot cameras which have a sensor area about 1/16th of full frame 35mm, very high pixel density (equivalent to about 64MP if extrapolated to 35mm size) are in desperate need of strong AA filters, when if fact the reverse is the case. The photodetectors on these small chips are so small, typically less than 4 microns, that there's no need for an AA filter. The lens is the filter. That's how it has to be if you want to extract the maximum detail the lens can offer, and Paul has very eloquently described what a huge difference in fine detail is available when the AA filter is removed from his Kodak 660.
Samirkharusi has made an interesting point that increasing pixel density also increases noise and reduces dynamic range and that low noise and high dynamic range are preferable. I wouldn't disagree with that. Given a choice between a resolutiom improvement with just a few high quality lenses and a real improvement in noise and dynamic range with all lenses, if that's the choice, I would choose the latter. But I would say that technology advances on many different levels simulataneously and I don't see any reason to assume that we've already reached a fixed limitation like diffraction. The D30, D60 and 1Ds all have different pixel densities, yet as far as I've read, they have very similar noise and dynamic range characteristics, with the 1Ds having the edge, particularly with long exposure night shots.
My final point is that it might be true that both the D60 and 1Ds (despite the AA filter) are close to the resolution limit of certain Canon lenses. When I bought the Canon 100-400mm IS zoom, I also got a 1.4 teleconverter. Having compared a few shots taken with and without teleconverter at the 400mm end, at F8 and F11, I see no advantage in the teleconverter. In fact, if one wishes to put a fine point on it, I would say that the 400mm scene enlarged 1.4 times more than the 560mm scene, sometimes shows slightly more detail. It certainly has better contrast. Since any teleconverter is going to degrade the image to some degree, I would be prepared to admit, at this stage, that the resolving power of the D60's sensor is probably the equal of the long end of the 100-400 zoom. But the long end of the 100-400 has never been described as crash hot, has it?
During the next few days I'll try to fit in a few experiments using the 1.4 converter with different lenses. In fact, I can think of no better way to resolve this issue of how close current sensors are to the resolution limits of the lenses. I've always been sceptical of the benefits of teleconverters because the simple fact is, once the image information has passed through the lens, then that's it. No matter what the quality of the converter, it's not possible to create additional lines of resolution that weren't there in the original image (from an aerial perspective). The best a 2x converter can do is double the size of the image whilst halving the resolution. If the main lens is really high quality with resolution to spare, so to speak, then halving the resolution would at least ensure that ALL the information in the aerial image is recorded on the sensor. If the image with converter, when enlarged on screen or print, shows more detail than the image without converter, enlarged to the same size, then that in my view would be proof that there's still need for more pixels.[/font]