Archived posting to the Leica Users Group, 2003/05/17
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>Hi!
> seems everyone is right here -- but I use mine OVER the GG, not in the
>camera. Made by Wisner -- I THINK you can get one from him that will fit
>most cameras, or do this to your own -- but it has a 'little' pull handle on
>the bottom so I can compose with it (don't forget -- the Fresnel Circles
>face the lens!), then easily pull it away to focus on a better plane, the
>ground glass. And, yes, even on the cut out corners of the GG I have THIN
>piano wire cross hairs that help focus on the airiel (Spelling??) image -
>which is very cool to see with a good loupe. The Fresnel helps with wide 9as
>mentioned) lenses as well as slower lenses that cover a good area. The
>Schneider G-Claron lenses are a great example of the latter. They are now
>discontinued I think, but despite Schneider's rec., they work fantastic as
>all around - even to infinity! - especially with B/W and a light yellow
>filter to avoid any secondary spectrum effects they 'claim' exist. But my
>color large format work (I've loaned my over 300mm G- Claron to 11 x 14
>color photographers!) with superb results. But now we are way OT!! :-)
>Ed
>>
>> Date: Fri, 16 May 2003 15:41:54 -0700
>> From: "Frank Filippone" <red735i@earthlink.net>
>> Subject: RE: [Leica] Fresnel lens question (ot)
>> Message-ID: <NEBBJDFBIKOBILIKPPBNAEIAMIAA.red735i@earthlink.net>
>> References:
>>
>> On the lens side of the GG...... at least the add on screens are like
> > that.... I am not totally sure about the Sinar specifically....
If the fresnel lens is put between the GG and the eyes, no
corrections have to made to the focus. That's why it's so handy. If
the fresnel screen is placed in front of the GG between the GG and
the lens, usually a correction has to be made to the screen placement
as the GG is now no longer at the same plane as the film will be, and
the fresnel lens and small air gap have to be accounted for. This can
be tricky. On the positive side, the optical performance is usually a
bit better if the fresnel lens is in front of the GG.
If you buy a camera with a permanently built in fresnel screen, it is
usually in front of the GG, and should not be removed. If your camera
has an optional screen, such as the Sinars, it goes behind the GG and
can be removed at will, and masks can be placed between the screen
and GG. This is a more versatile approach, and that is what Sinar is
all about.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com
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