[largeformat] formula for heligon

[philip Lambert]

If it helps, the 80mm Schneider Xenotar f2.8 5 element covers a circle of
98mm.and has a flange to film distance of 73mm. I haven't been able to find
what size shutter it's in .  My  23 S.Graphic came with a 105mm f3.5 Xenar
fitted .   The Xenotar was evidently a five element development of the
Xenar. Xenotars are said to be very sharp but  rare.   Philip
----- Original Message -----
From: "Les Newcomer" <lnphoto@twmi.rr.com>
To: <largeformat@f32.net>
Sent: Tuesday, December 25, 2001 3:32 PM
Subject: [largeformat] formula for heligon


> Okay so this isn't strictly speaking, largeformat, but the right people
> are on the list.
>
> I've been trying to get a fast 80mm lens fitted to a 2x3 Pacemaker Speed.
>
> I picked up an 80 Planar (f2.8) but found that the bed wouldn't close
> with that huge shutter on it and while it wasn't a real problem, I did
> need to remove the rear cell to mount the lens.
>
> I then found an 80 2.8 Heligon. the shutter much smaller, the front cell
> glass is the same diameter but the rear cell is much smaller.
>
> Kingslake says that this may be a Planar formula, but if that's true how
> could they get away from the big rear end?
>
> Ken hough suspected that this may actually be a Tessar, since Rodenstock
> has been known to use the name Heligon much like Kodak used the name
> Ektar--not to denote a lens formula, just a brand name.
>
> He also noted that the front cell of a tessar won't project an image.
> The theory of this being a Tessar would solve the mystery of the small
> rear cell, but I was worried it wouldn't cover 6x7.
>
> so I tested this mystery Heligon. The front cell DOES project an image.
> Infact it's (very rough estimate) of 4" focal length.  The rear cell is
7.5".
>
>
> So does anybody out there know what the specs are on an 80mm f2.8
> Heligon? Will it cover 6x7cm?
>
> LEs
>
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