Archived posting to the Leica Users Group, 2001/08/13

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Subject: Re: [Leica] correction lenses
From: "Julian Koplen" <jkoplen@mindspring.com>
Date: Mon, 13 Aug 2001 12:25:18 -0400
References: <53EB67411602D211846900A0C9C7647A0FD7917D@mail3.pica.army.mil> <001c01c12113$bee10e00$ab631b3f@hoolio> <OE52XfyY0QUUBPcZi710000011a@hotmail.com> <009701c122a2$83533800$c95c193f@ntr.net> <OE641xlrsW00VJkNGSd00008daa@hotmail.com>

The element he made was perfect to my eye, and I could detect improved
performance when I aligned the axis properly for my astigmatism.  That is
done by estimate.  There are no azimuth numbers on the tiny eyepiece frame.
He took about a month or 6 weeks to make the lens, but that could possibly
vary with his circumstances.  He was in the process of moving into a new
residence, when I asked him to do my work.

I thought the virtual image was at 1 meter, but you may well be correct. At
any rate, you have the correct concept.  My farsightedness and inability to
accommodate are such that I need correction at all distances, including
infinity.

I hope this helps.............Julian


- ----- Original Message -----
From: "Mxsmanic" <mxsmanic@hotmail.com>
To: <leica-users@mejac.palo-alto.ca.us>
Sent: Sunday, August 12, 2001 7:40 AM
Subject: Re: [Leica] correction lenses


Julian writes:

> The man who did mine charged $200 USD.

Sounds reasonable.  Is the element he made visually clean (that is, no
anomalies
when you look through it)?

> This is because Leica builds a -0.5 into the
> camera's eyepiece.

Hmm ... so the virtual image is 2 metres away in the viewfinder (if I
remember
the application of diopters here correctly), which implies that you would
need
correction if you have trouble at this distance.  From what I've read,
almost
everyone (even those slightly nearsighted or farsighted) can see pretty well
at
a distance of 2 metres, which is why this distance is frequently chosen for
viewfinders by camera makers.

> I have admired the pictures on your website.

Thanks!

In reply to: Message from "Nguyen, Olivier T [AMSTA-AR-CCF]" <onguyen@pica.army.mil> (RE: [Leica] correction lenses)
Message from "Julian Koplen" <jkoplen@mindspring.com> (Re: [Leica] correction lenses)
Message from "Mxsmanic" <mxsmanic@hotmail.com> (Re: [Leica] correction lenses)
Message from "Julian Koplen" <jkoplen@mindspring.com> (Re: [Leica] correction lenses)
Message from "Mxsmanic" <mxsmanic@hotmail.com> (Re: [Leica] correction lenses)