Rob, A few years ago I did something like that using a damaged SMC filter. I couldn't see any scratches or abrasions, even when using a magnifier. However, I did ruin a 20mm Super Tak by cleaning it with Kodak lens tissue. although I couldn't see the scratches. When I brought the lens in for a CLA, the technician, by knowing where to shine lights, etc., showed me the problem.
Shel > [Original Message] > From: Digital Image Studio > Lifted directly from a post I made re lens cleaning Nov 2000: > > In an except from the Leica Fotographie International magazine 6/99 page 37 > the following can be found: > > "The resistance and adhesive power of the outer layer is so good that there > is little likelihood of damage by environmental influences or persistent > cleaning on the part of the user. Numerous abrasion tests have been carried > out. There is one that uses a rubber eraser which contains up to 50% > pumice-stone grains. The standard test is to rub backwards and forwards 20 > times with a pressure of 1kg. Afterwards, no scratches should be visible on > the lens surface." > > Although this passage refers to Leica coatings and practices I would be quite > disappointed if the late Pentax coatings didn't exhibit the same wear > resistance. Anyone care to run the above test on a neglected piece of SMC > hardware? -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
