[rollei_list] Re: rollei focussing screens
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Mon, 24 Sep 2007 13:29:05 -0700
----- Original Message -----
From: <aghalide@xxxxxxx>
To: "rollei list" <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, September 24, 2007 12:24 PM
Subject: [rollei_list] rollei focussing screens
Regarding the freznel add on focussing screen, of
yesteryear. Do you plop it in onto the existing permanent
screen.....does it go, freznel side up or down? Regarding
the fully interchangeable focussing screen, does that go
rough side up or down?
Ed Meyers
The Rolleigrid does just drop onto the existing ground
glass with the grooved side facing the top of the GG. Rollei
cameras from about 1950 have two little springs and a tab to
hold the screen. These are also used for the finder mask of
the Rolleikin and I find I can not use both together. In any
case, the uniformity of the basic ground glass over the area
used with the mask is good enough not to need the
Rolleigrid.
A similar Fresnel lens was made by Hartley in the 1950's
and 60's for the Rollei and several other cameras.
I am not sure about the interchangible screen.
Ideally, to get best unifority and to minimise internal
reflections, a Fresnel should be between the ground surface
and lens with the grooves facing the ground surface but this
will displace the ground glass in cameras not designed for
it. This is the arrangement used in the Graflok back of
later Speed and Crown Graphic cameras. While ideal the
actual difference between this and just laying the Fresnel
over the ground glass is very slight.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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