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     Rick_oleson Tinkerer Username: Rick_oleson Post Number: 554 Registered: 07-2006 Rating: N/A |
Dust specks generally won't have a measurable effect on photos unless they're just horrendous: the effect of a speck of dust is usually to absorb the light that hits it, preventing that ray of light from reaching the film.... so it becomes a function of the percentage of the lens area that's blocked by the dust specks, probably a small fraction of a percent. Scratches, and particularly cleaning marks, are another story: they cover a much larger area of the surface than dust specks do, and rather than absorbing light they scatter it. The scattered light bounces around inside the lens and does reach the film, but not in the locations where it's supposed to. Its effect is generally to reduce contrast by scattering light into areas of the picture that are supposed to be dark. And, if the performance of that Perfex 55's lens was similar to mine, a bullet hole probably wouldn't make it that much worse..... : ) = |