On Tue, 28 Jan 2003 21:01:13 GMT, Robin Burns <r_f_burns@hotmail.com> wrote:

>Neuman - Ruether wrote:

[...]

>> We've been here before, but, once again, a good UV

>> filter does nothing but protect the lens. It does not

>> block appreciable UV that is not already blocked by

>> the lens glass, and it does not reduce sharpness.

>> Under most circumstances, it also does not increase

[...]

>Correct on the UV point, but not with respect to sharpness. Adding another

>piece of flat glass in front of a lens that was not computed to take this

>into account will certainly degrade sharpness. This is all a matter of

>degree, however, and most people will not notice any difference, especially

>if they don't enlarge the image greatly. Critical users can and do notice

>image degradation.

This is not true. While the "theory" says "yes",

in practice *there is no noticeable difference in

sharpness with or without good UV filters in place*.

I have done the tests, and I am VERY particular!

Optical problems with adding filters will show

most with long, fast teles used wide open (filter

refraction effects *do not* affect wide-angle

image sharpness, also by my tests...) - and on a

clear day, shooting with a 400mm f3.5 EDIF Nikkor

at f3.5, adding/removing the front and/or rear

filter(s) had NO effect on fine detail rendering

(assuming refocusing with removal/replacement of

the rear filter). Period. It is time to get

rid of some of the few remaining myths in still

photography...;-)