Archived posting to the Leica Users Group, 1997/12/12
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Hi Folks -
I've seen both nuetral and bad effects from filters [on LEICA cameras]:
I recently tested a Contax rangefinder, with and without an MC filter. I wasn't
testing for filter influences, but I didn't notice anything unusual [using a
LEICA stereo microscope on the film].
On very high contrast material: I do recall seeing a bright neon sign bouncing
around in front of a 50mm SUMMICRON. The "original" was off-axis in the
upper-left quadrant, and the "ghost" was in the complimentary position in the
lower-right quadrant.
I'm looking at a Canon rangefinder lens guide, and they show the 25mm f3.5 (a
neat lens for your LEICA III but a bit clumsy to change the f-stops). Get this:
The diagram of the lens shows 4 elements, all severely crescent-shaped (a wild
lens you should see it). But anyway, there's a fifth element at the very rear
and guess what: It's a FLAT piece of glass!!! Canon says in the book that
"Aberration compensation balance of this lens is achieved at the rear plane
with special optical glass." So one would assume that flat glass [in front of
or behind your lens] will change the lens characteristics
... though I have yet to be convinced that my Super-Angulon should go running
around naked for basic street shooting.
- - Jesse
(If anyone has a neat unix script to filter LUG mail which doesn't contain
Leitz trademark keywords please let me know :) )
> 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.
- --
Silicon Graphics USA
Jesse Newcomb Mountain View, CA
jessen@sgi.com tel 415 933-2026
http://reality.sgi.com/jessen_esd fax 415 390-6159