----- Original Message ----- From: "graywolf" <[EMAIL PROTECTED]>
> Actually it is grease. What happens is sometimes a lens gets hot (perhaps left > in a hot car a lot), and the grease from the focusing helical migrates to the > aperture blades sometimes making them sticky. When the happens they is usually a > film of grease on the glass too, which does nothing for the image quality. The > fix is a complete tear down, cleaning, and relubrication often costing more than > you paid for the lens. If it happens to be a cheap zoom, you might as well toss > it in the trash. I had a SMC-M 35/2.8 with sticky aperture blades. To the point where exposures got weird from the sluggishness. I opened an cleaned it myself. It was a fairly simple thing to do, actually, but I wouldn't tempt it with newer lenses (A/FA- series or zooms). You have to disassemble the aperture ring. With M-series and older that's quite straightforward, but with the newer lenses there are all sorts of small fiddlybits in there. Jostein
