Archived posting to the Leica Users Group, 2001/07/27
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At 8:19 PM -0400 7/27/01, Austin Franklin wrote:
> > It seems to me that the real issue with a filter is whether or
>> not the glass is
>> truly flat and appropriately coated. If it is flat, the index of
>> refraction and
>> dispersion shouldn't make any difference, anyway. And coating
>> can hold down
>> flare.
>
>Additionally, coplanar and perpendicular to the axis of the lense. Any of
>those issues can cause trouble.
These problems don't seem to be as bad anymore, but when I bought
filters in the 70's I sometimes had to go through a dozen or more
before I found a useable one. Sometimes I never did find one. The
coplanar issue seemed to be a problems for a number of manufacturers.
The only brand, and I include Leica, B+W and Heliopan in this, that I
never had a problem with was Nikon. Unfortunately, they had (have)
only a limited range of colours and sizes. The worst were Harrison &
Harrison.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com