Archived posting to the Leica Users Group, 1997/12/15

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Subject: Re: [Leica] filters for M-lenses
From: jeremy.kime@bbc.co.uk (Jeremy Kime)
Date: 15 Dec 97 10:53:00 GMT

>> Jesse Newcomb   wrote...

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
 --

I had a 25/3.5 Canon which did the darndest thing when I put (kept) a filter 
on it. Although it was a Canon filter, I think they were the only firm that 
produced 40mm filters... It created a vignette at the corners (perhaps it 
was one of their thicker ones, I've learnt now they made them in three 
thicknesses) though NOT a dark vignette but a light one!! Wierd! It was a 
silver filter and my only theory was that it was a reflection (unlikely) 
coming back into the camera...
It was a cute lens though, tres petite, eventually the camera was dropped, 
the finder was broken, and the lens was 'useless'. I sold the lens to Paul 
Henry van Hasbroeck and recieved an insurance cheque to enable the purchase 
of my first Super Angulon. Many years later I coaxed a reshaped lens element 
to vaguely replace the missing front element in the finder and sold that as 
well.

The funniest incident happened a day or two after I'd got the lens, I was on 
the seafront at Skegness, a small seaside town in Eastern England and saw a 
fight between some 'bovver boys' and the police. I put the camera to my eye 
and ran towards the fight, anxious to be ready to fire the shutter as soon 
as the composition was right. I got there, took a couple of photos of the 
three policemen restraining three lads and then put the camera down, I 
nearly jumped out of my skin! I was only two feet away from them all! The 
phrase, 'Get in close' comes to mind, but boy, does that photo have impact!
Jem