[Leica] Re: filters etc.

[Jim Brick <jim@brick.org>]

At 09:56 PM 12/12/97 -0500, you wrote:
>At 06:37 PM 12-12-97 -0800, Jim wrote:
>[snip]
>>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."
>
>I'm still waiting for someone to show me a before/after example of the
>detrimental effects of using UV filters on Leica lenses.  I'm less
>interested in what effect some optical engineer at the factory says that a
>filter *may* have on the optical properties of a lens.  I want to be able
>to see it.
>
>Dan C.

Degradation eats away a little at a time. Each thing (filer, dust/dirt,
flare, etc.) may not be detected by itself, but when added together,
produce a seeable effect. A filter is always prone to flare, while, in many
cases, the lens that it covers, will not produce flare in the exact same
situation. So, as far as I'm concerned, by attempting to take care of each
and every thing, then none can sneak up on you and degrade your results.

Everyone has his or her own "comfortable" way of working. Mine happens to
be toward obtaining the absolute maximum sharpness. I, therefore, keep my
lenses super clean, use Velvia, weight-down my camera, lock-up the mirror,
only use a filter if the scene warrants it... etc. Quite often, I will
photograph something both with and without a filter, just in case. It's
very disturbing, when you are limited to an 11x14 print instead of a 16x20
or 20x24, because of some unwanted artifact. This happened to me not long
ago because I used the 35-70 zoom instead of a prime lens, was using an
R4sP (no mirror lock-up), and a shutter speed of around 1/8th sec. It all
added-up to less than desired sharpness. The 11x14 (a Lake Tahoe sunset
scenic) is nice but it would have been better larger. I have a similar
photo of Pikes Peak at sunrise. Same equipment and exposure range. The best
it can do is 11x14. This is not the case with most of my work. When I am
able to control each and every step of the process, the results speak for
themselves.

This is a "to each his own" topic. Like war, it can be argued for
centuries. But shouldn't. There are a simple set of rules that, when
followed, will give you maximum results. If you cannot attend to all of
them, then you have to be prepared to *possibly* accept less. That doesn't
make it any less rewarding. My 11x14 Tahoe & Pikes Peak are nice. It's the
best I could do and it's OK. The ultimate use for a photograph will quite
often dictate how much effort you will exert.

You do what you can, and that's all you can do.

Jim