On Jun 29, 2004, at 8:10 AM, Jonathan Coleman wrote:
Bob, thamks for this but it is a bit of a worry!!
How much of an issue is this likley to be in studio portraiture and how easily are the fixes?
I know a few portrait shooters that use nothing but this camera, and portraits are almost all they do, so it can't be that much of an issue... but you need to be aware of it. It's not a huge issue. I won't affect a large percentage of your shots but Murphy's law being what it is, it will show up when you least expect it and when it's possible to cause you the most grief. Chroma moire can be dealt with in a number of ways. My favorite in Moire Eraser that comes with Quantum Mechanic. Quantum Mechanic is available for Mac or Windows but the Moire Eraser is only on the Mac version. Simply sampling the appropriate color and painting with a soft brush in color mode is also a simple fix. Usually this occurs in fabric where you don't need to apply the fix to an extremely precise selection so it can usually be done very quickly. Keep in mind also that these cameras have such hi-res chips that this kind of problem occurs only on very fine detail. As such even if uncorrected it likely won't show on small prints. So its not like you have to correct dozens of images just to show some proofs. That wasn't true of earlier cameras with lower res chips and no AA filter.
You can also prevent these types of artifacts by doing anything that very slightly softens the image. That (in over simplified terms) is what an AA filter does. You can accomplish this by shooting a very small apertures where the lens/chip combo can't resolve as well... like f22. You can use a very slight soft focus filter. If the problem is the texture of the fabric, then softer lighting that doesn't emphasis texture will help.
These filters are made specifically for this problem. I've not tried them but if I shot portraits on a more regular basis I'd be inclined to:
http://www.caprockdev.com/antimoire.htm
Bob Smith
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