Archived posting to the Leica Users Group, 2000/03/16

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Subject: Re: [Leica] Focusing at infinity
From: Ted Grant <tedgrant@home.com>
Date: Thu, 16 Mar 2000 17:24:06 -0800

"Dale R. Reed" wrote:
> 
> I have been doing some more measurements.  I learned that I must be much
> more careful focusing because with glasses it is easy to have your eye
> shifted enough to get a false reading.
> 
> I measured my new 135mm, a 90mm, a 50mm, and an older 135mm.  I measure
> essentially the same results with both of my M6s.
> 
> I have concluded that I really cannot measure any errors for the 50 and 90mm
> lens.
> 
> But the brand new 135mm is way off.  At 10 feet, 20 feet, and 30 feet the
> lens reads 11-12 feet, 30 feet and 45 feet.
> 
> The older 135mm lens reads 11 feet, 22-25 feet and 35-40 feet so it is not
> doing so hot either but it will focus(according to the rangefinder) at
> infinity but the new 135mm lens will not.  And the older lens is a little
> loose mechanically.
> 
> So either my new 135mm lens is actually constructed/adjusted/whatever wrong.
> Or the rangefinder is adjusted OK for all my other lens but is not adjusted
> correctly for the 135mm lens.   Maybe it is very difficult to provide a
> rangefinder for a 135mm lens.
> 
> So what do I do next?
> 
> Do any of you think that if I tried another new 135mm lens it would measure
> correctly at 10 feet, 20 feet, and 30 feet and at infinity?    >>>>>>>>>>>>>>>>

Dale me old son,
Stop sweating where the little lines are on the lens. any of them.  Put
film in the camera, focus on something at a mutitude of distances and
shoot one frame or two on each, soup the film and look at the "sharpness
results!"   If they're cool and crisp, your laughing! 

Then you can  quit thinking about the little lens footie markings as
they really aren't relevant to anything as long as the range finder
gives you sharp images.

ted