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Created: 2008-09-11 15:46:04
By: Paul Derbyshire (Twizzler)
Summary: RGB filters.
CCDs are actually indiscriminate as to color and just sense luminosity, so there are RGB filters in front of your camera’s CCD array, typically in a pattern like RG, GB in a repeating 2×2 array. If the filter has become ever so slightly distorted (perhaps slightly expanded in size) or misaligned, the light reaching elements of the CCD array designated in the camera firmware as say “red” may be green, etc., and you get odd purple tinting like exhibited here as light reflected from green objects makes it to CCD pixels that are only supposed to receive red light, and thus gets interpreted as red. The gradient from left to right indicates that the filter grid has changed size slightly, or buckled slightly along a vertical line about 1/4 of the way from left to right.
The upshot: It’s probably cheaper to replace the camera than to repair it, as the affected components are basically on a thumbnail-sized chip behind the optics and couldn’t be separately replaced or fixed without tweezers and a microscope.
There are 7 megapixel cameras with tripod mount screw-hole, 10x optical zoom, and image stabilization going for under $300 these days. Don’t bother to splurge on fancy lenses or detachable flash; even for “macro-photography” you can get away with a $250 camera and a finger or bit of paper in front of the flash to reduce/diffuse the light. Tripod-mountability, decent resolution, decent autofocus, and decent optical zoom are the only strong requirements for mushroom photography. The ability to viewfind using the LCD screen is crucial, too, though, so make sure the thing is decently backlit, and be sure to carry plenty of spare fully-charged batteries!
The ability to browse your photos with the LCD screen is also valuable, especially the ability to close-up while browsing and see the center of an image at full resolution. That’s the only way to be sure a photo is good, since a fairly blurry one can still have a sharp 200×150 downsampled thumbnail! And you’ll want to be able to tell if a shot needs to be re-taken while still in the field.
Suitable cameras exist in the $2-300 range, at least in my neck of the woods. In the states you might even have them in the $150-200 range with the above feature-set.
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