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

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Subject: Re: [Leica] Focusing at infinity
From: "Dale R. Reed" <dale-reed@worldnet.att.net>
Date: Thu, 16 Mar 2000 16:11:10 -0800

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
- ---
$ dale-reed@worldnet.att.net    Seattle, Washington USA $