[Leica] Re: Mike and filters

[Jim Brick <jim@brick.org>]

At 11:04 AM 1/28/98 -0500, mike wrote:
>
>P.S. To Jim Brick: I agree with you about filters, with the caveat that it
only
>really makes a difference with the best lenses and presumes that the
>photographer cares about--and knows enough to recognize--optimum optical
>quality. With some lenses a filter will add unacceptable flare or
reflections,
>or cause contrast reduction, and in some other cases its effect may not be
>noticeable. But as many LUGgers have no doubt discovered, the better the
lens,
>the more likely it will be that you won't want a filter on it. To quote
>Kornelius Fleischer of Carl Zeiss, "No filter ever _improved_ the technical
>performance of any lens."
> 

Thank you Mike, but besides 50 years of experience, I also rely on the
printed word.

I have a publication called EPOCH and was produced by the National Camera
Exchange. This particular issue is dated Fall/Winter 1985. The article was
called "Lenses Are Just Made of Glass." It states that "Leitz developed a
special cement, replacing the Canada Balsam, that had the properties of a
UV filter." They state that this was developed sometime in the fifties. So
that could be 1959 or 1950. This is also the article that a Leica lens
designer was quoted... "If we had meant for our lenses to have a flat piece
of glass in front, we would have designed them that way." The article also
said that "any filter adds aberration, very much like spherical aberration.
This will be more pronounced with thicker filters, but even thinner better
filters, produce this effect."

Per Leitz document #920-083 "Even high quality filters may create problems
in certain situations. High contrast, sunrise, sunset, night shots, bright
light sources in the frame. These can cause general degradation of the
image, loss of contrast, and double image. Remove all filters in these
kinds of situations."

Jim