Archived posting to the Leica Users Group, 1997/04/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
>It might be helpful to us if you would elaborate on exactly how you made
>the determination that the lens coating was flawed.
>Also, if the flaws were not glaring, did it take much convincing of the
>people at BandH to see the defects?
>Thanks.
>Mark Berkley
I looked at the lens! In normal room light I turned the lens (front and
rear elements) so that the light caught the color of the coating. I scanned
across the surface of the lens and found spots where it looked like a
bubble had formed and then burst. There may never have been an actual
bubble there, but that's what it looked like. In other cases I saw places
where specks seemed to be missing coating, as if it had flaked off. Both of
these defects were apparent by the lack of color: they looked like small
mirrored spots.
Optically I'm not sure that the front element spots would have caused
problems in most shots. The rear element defects worried me more. But even
if they wouldn't produce noticeable deterioration of the final image, they
leave me wondering whether the coating will be durable, whether it was
applied correctly. In a lens that expensive I expect that the functional
elements of the designe be in perfect order. I'm not as enamored of the
exquisite engraving of the distance scale and such things that collectors
prize, but lens coatings are fundamental the performance of the lens.
B+H had no qualms about accepting the two returns. I sent them back
promptly, explained the problem, and requested an exchange. B+H has always
been fair to me. I have no idea, however, whether they returned the two
imperfect lenses to Leica or sold them to someone else. I suspect the
latter since the lenses did pass Leica quality control. Perhaps they will
work just fine, but the three bad areas that I found on each lens nagged at
me.
- -Charlie
- --------------------------------------------
Charles E. Dunlap
Earth Sciences Deptartment
University of California
Santa Cruz, CA 95064
Tel.: (408) 459-5228 Fax.: (408) 459-3074
- --------------------------------------------