Re: [Leica] help: which correction eyepiece ?

["Bill Larsen" <ohlen@lightspeed.net>]

Many thanks to Richard Clompus, OD

This is the most succinct summary that I have ever seen.  You nailed my =
demographics and it would almost be worth moving to PA to have you as my =
optometrist.  Because of frustration with getting a straight answer from =
local ODs, I have gone the "dime store" route and have various cheap =
glasses for use with for computer screen, reading, and "fish hook" =
baiting.  I have yet to find an OD who will listen to what I want to =
focus on.  (I used to shoot revolvers, and when I said I wanted a =
prescription that would keep the sight in focus while still giving a =
reasonable focus on a target 25 meters away, I was told that it was =
impossible.  I use a correction from 1.5 to 2.25...depending.  Thanks =
for the straight answer...Next I shall self-correct my Leica.

Regards,  Bill Larsen
mailto:ohlen@lightspeed.net

- -----Original Message-----
From: Richard Clompus <rclompus@voicenet.com>
To: leica-users@mejac.palo-alto.ca.us =
<leica-users@mejac.palo-alto.ca.us>
Date: Tuesday, March 03, 1998 2:39 PM
Subject: Re: [Leica] help: which correction eyepiece ?


|Andreas Frijdal wrote:
|
|<snip>
|I am wearing glasses with variable focus +1.25 to +3.25.  What is the
|appropriate eyepiece correction I should buy.
|<snip>
|
|I will try to give you some advice on this subject.  The above =
prescription
|indicates you are probably between 48-52 years old (I'm not psychic) =
and
|are farsighted.  The variable focus lens you mention is probably a
|progressive addition lens (PAL) and is considered a bifocal without =
lines.
|If you view through the upper portion of the lens (+1.25 diopter), it
|should give you clear distance vision.  As you lift your chin up and =
view
|through the middle or lower area of the lens, you get the bifocal =
effect
|(up to +2.00 diopters in your case). =20
|
|Technically, you should use the distance prescription (+1.25 diopter) =
for
|an eyepiece corrective lens for a camera.  Some SLR viewfinders project =
the
|image of the ground glass out to about 1 meter and not optical =
infinity.
|So to focus at this distance, you may need an additional 0.50 to 1.00
|diopter strength above your distance prescription.  The lens' total
|corrective power can be simply added for the final prescrpition.  So if =
the
|image through the camera is clear with your distance prescription, then =
go
|with the +1.25 diopter lens.  If it is still a bit blurred, you may =
need
|either a +1.50 or a +1.75 diopter lens to clear it.  Most corrective =
lenses
|come in increments of 0.50 diopters. =20
|
|For the M Leica, I would recommend your distance correction (+1.25
|diopter).  If you can't get this power, you could then go with either =
+1.00
|or even +1.50.  Fortunately many of the professional SLRs today come =
with a
|built-in diopter compensation wheel so you can simply dial in what you =
need. =20
|
|The M6 Leica has a thin rubber gasket around the eyepiece to prevent =
you
|from scratching your glasses.  You should remember that with a =
prgressive
|bifocal lens, if you view through anywhere except the top of your =
glasses,
|the image will be blurred.  Learnt o keep your chin down when looking
|through the camera with your glasses on.
|
|This is sometimes a difficult subject to grasp.  If you need more help,
|please feel free to email again.  I hope this cleared things up for =
you.
|
|Happy shooting,
|
|Richard
|---------------------------
|Richard Clompus, OD
|West Chester, PA, USA
|