Re: [Leica] Filters and Lens Testing

[apbbeijing <apbbeijing@yahoo.com>]

I use filters often and of many different types (with about 200 at last
count) but I don't think any amount of lab testing of filter-caused image
degradation is going to tell you what you need to know: that can only be
found through practical shooting. Nevertheless I welcome any meaningful
research on the matter.

Now if there is a logic for camera lenses to have a protective filter,
surely there is an even greater one for enlarger lenses to have them: but
you won't find any Uvs in front of my S-Biogon nor my Focotars!

Many pros regard UV filters as less than useless: like ERCs. Many others,
myself included, keep UV filters on many lenses as a form of protection.
This is mainly for the lenses that get thrown in the bag in the heat of
shooting rather than for the most expensive or vulnerable optics: my
ultra-wides, macros and long teles have no filters left on nor my MF and LF
lenses but most of my most used 35mm lenses do. I use current B+W MRC UV
filters for the most part and find them best in terms of flare resistance,
cleaning ease and scratch resistance. I do however frequently remove them:
when I am shooting a job where I expect to need a variety of colour or
contrast correction filters I leave the Uvs at home since they otherwise get
in the way. Shooting at night: leave them at home or live with annoying
secondary images all over the picture. There are many other situations where
I would hold the UV and many others where I would not worry but it is only
through experience (i.e. Having screwed up) that I now know when to avoid
them. My advice is get the experience or leave them at home. I spent far
more on UV filters than all the lens repairs I have ever needed.

With Leica Ms the large number of obscure filter sizes and the fact that you
cannot see the image until it is developed makes Uvs an expensive hazard
IME. I find the worst cases of image degradation I experienced due to the
old chrome rimmed Leitz  Uvs. Wouldn't recommend them for general use.

IME sharpness loss is undetectable but contrast tends to suffer with
filters. I am often staggered by how many macho filter scoffers don't use a
decent lens hood which is part of the original lens design: that is asking
for problems IMHO. But if one gets extremist about these things then a $10k
tripod and a concrete foundation is de rigeur and you can forget about sharp
photos in Southern California and other earthquake prone locations: like
Japan for example (but then we knew that ;^) )

Rs

Adrian



- -- 
Adrian Bradshaw
Corporate and Editorial Photography
Beijing, China
tel/fax +86 10 6532 5112
mobile +86 139 108 22292
e-mail apbbeijing@yahoo.com
OR adrianpeterbradshaw@compuserve.com

website:   http://www.apbphoto.com
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