Archived posting to the Leica Users Group, 2002/03/09

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Subject: Re: [Leica] Re: viso III brightscreen replacement
From: Dr.Alexander.Kraus@gmx.de
Date: Sat, 9 Mar 2002 10:58:33 +0100 (MET)
References: <20020307193047.94519.qmail@web21305.mail.yahoo.com>

Hello Rei,

I recently modified my Visoflex III. It is now as bright as my Leica R5!
First I replaced the ground glass (yes, its really glass) by an original
Leica R ground glass.
In order to do so, I had to cut of the "holding nipple". That was no problem
since the screen consists of plastic. 
There are no shim rings to worry about. Just make sure that the grounded
surface faces down and the fresnell lens surface faces up (be careful not to
scratch the surfaces).
If you now look through the pentaprism finder or the vertical loupe, you
will recongnize that the image has already become much brighter in the center,
but that there is a significant falloff in brightness towards the edges. This
is caused by the fresnell lens. The original ground glass doesn't have an
integrated fresnell lens. Here, an even illumination is achieved by a biconvex
lens in the pentaprism or vertical loupe finders.
The introduction of the fresnell lens in addition to the light collecting
lens results in a overcompensation.  Thus, it is necessary to remove the
biconvex lens. This is really easy done, since the lens is easy accessible. Its the
one that faces down (directly above the ground glass).  You just have to
remove the chrome bottom plate of the finder. Than you can now take the lens out
and put the chrome plate back where it was. That is all!
You will be amazed how bright your Visoflex will be - its a whole new
experience! :-)
The good thing is that you can restore the visoflex to its original state
any time (in case you want to sell it).
Have fun :-)
Regards from Germany,
Alex

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Replies: Reply from Dr.Alexander.Kraus@gmx.de (Re: [Leica] Re: viso III brightscreen replacement)
In reply to: Message from Photo Phreak <leicam4pro@yahoo.com> (Re: [Leica] Re: viso III brightscreen replacement)