Re: Filters

[Jim Brick <jim@brick.org>]

Doc, this response is not meant to be condescending, so please take no
offense, it's just the way I see it...

At 08:19 PM 9/23/97 -0400, you wrote:
>I am one of those who prefers to keep a top-quality, coated or multi-coated
>UV filter on my lenses most of the time. I do believe it will
>protect it from chemical and particulate contaminants which are in the air
>everywhere, always.

Doc, where do you get filters that form a hermetic seal to the lens front?
I suspect your lungs will have more of a problem with these contaminates
than your lens will. I believe cement degradation and other internal
(protected by Leitz seals) problems will destroy your lens internals before
our breathable (albeit yucky) air will destroy the outside of the front
element. And what about the back element?

>  I also believe it will protect my lens' coating from the
>cumulative effect of years of even the most careful, gentle cleaning.

Probably true on old soft coated lenses. I do not believe modern lenses are
soft enough to worry about. Just be somewhat careful. How do you know when
you have cleaned away the filter's coating? You could be, without knowing
it, shooting through uncoated glass.

> I am
>particularly concerned with those lenses which have huge (like 122mm or
>160mm) front elements which would cost dearly to replace.

My Leica 15mm R lens has a huge front bulbous element and NO filter
threads. This is probably the most expensive front element I own. The 19mm
R and 16mm R also do not have filter threads. Pretty difficult keeping them
away from the bad air.

>I suggest that anyone undecided on this issue should shoot a test roll of
>fine-grained slide film of various subjects in various light, alternating
>frames with and without the UV filter.  Examine the slides on a lightbox with
>an 8x loupe.  You will then have your own definitive answer to this most
>controversial subject.

I have used filters in many different lighting situations. Actually, I
nearly always use a filter of some sort for image correction... of course,
depending upon where the sun (or bright light) is. You can usually see
first hand, when using an SLR, if image degradation is going to take
place... BUT NOT ALWAYS! And after looking at your tests with a lupe, will
you remember, the next time you are shooting with your M, whether or not
this is a "no filter" situation? Or will you forget that the filter is on
the lens?

Using filters, whether for front element protection or image correction, is
a very personal thing. R users (me) have it much easier as we are looking
through the filter. And I suspect use filters far more than M users. If I
were using an M camera, I would probably never use a filter and always have
the lens shade either attached or extended.

The lenses one uses and whether or not a filter will make a difference,
depends entirely upon the end use of your photography. Normally I shoot
with my Leica R for book publication. If the image is good enough, it may
end up as fine art (poster or display print.) I personally try to always
use a tripod, Fuji Velvia, mirror lock up, and Leica's very best lenses.
For me, an unnecessary filter has the *possibility* of degrading the image.
Something which has bit me in the but more than once. After going to all of
the aforementioned trouble (MLU, tripod, Velvia, etc.), I will not allow
anything to unnecessarily degrade my product. We are already at a
disadvantage. It's 35mm. What you may not see in an 8x10 or 11x14, you sure
as hell will see in a 16x20 or 20x24.

If I were shooting reportage, street, happysnaps, etc... then my opinion
would be different. But as it is, I need every single mm of resolution I
can get.

The filter I use most is the polarizer, second the KR3 warming, third the
split ND (.3 & .9, soft & hard.)

Jim

ps... I somewhat apologize for the filter abuse. But I have a very strong
opinion. Did anyone notice???  :-)