On 29 Jan 2003 19:02:58 GMT, pschings@aol.com (Pschings) wrote:

>One example from the site:

>

>50mm f/1.8 Zuiko (multi-coated, late "Made in Japan" variant)

[...]

>Aperture Center Corner

>f/1.8* B C-

>f/1.8 B+ C

[...]

>lens was

>refocused after attaching the filter; no detectable contrast

>difference with and without filter.

>

>Another:

>

>Leitz 90mm f/2 Summicron-R (1978 era 3-cam)

[...]

>Aperture Center Corner

>f/2* C+ C

>f/2 B B

[...]

>Again, this is meant as just another data point. YMMV.

Thanks. In testing lenses, I have observed that even with

excellent viewfinders and very sharp eyesight, and with

time, if I focus VERY carefully for each of four frames,

with a 10X magnifier, I can just detect sharpness

differences which are attributable to focus variations

alone. With filter tests, I chose a very long and fairly

fast Nikkor 400mm f3.5 (that is quite sharp at f3.5 - and

teles tend to show up filter defects more than short

lenses) and focused multiple frames wide-open with

and without front and/or rear UV filters in place, with

results showing differences within the focus error range,

and with no predominance of "with" or "without" frames

for best results... I'm satisfied that the use of UV

filters does not materially affect lens sharpness

(I also tried this with wide-angles, and found no

difference). Sorry to be repetitious, but I tend to

believe my own findings over others, unless virtually

everyone finds otherwise, especially those whose

techniques and knowledge I'm familiar with and respect...