[LargeFormat] Ross lens, Epsilon shutter

[mark blackman]

I have a Wray 135mm f 4.8 Lustrar lens mounted on an Eplsilon shutter (B, T,
250 - 1 sec) which I use on a Crown Graphic (serial no: 916034) & I'm
pleased with it's operation. Not sure how this compares with the 5" WX
Xpres.

----- Original Message -----
From: "Clive Warren" <cocam@blueyonder.co.uk>
To: <largeformat@f32.net>
Sent: Sunday, April 21, 2002 9:06 AM
Subject: Re: [LargeFormat] Ross lens, Epsilon shutter


> At 8:00 am +0100 21/4/02, philip.lambert wrote:
> snip
> >supplied German needs at the time?) The 5" WA Xpres probably replaced
> >imported  LF lenses like Xenar and Ektar. Wray also made LF lenses for
> >British MPP then. (avoid their 89mm).  I should guess it had an extra
> >element for the added corrections needed to allow f4.5 on a widefield
lens
> >unless you were expected to stop down a lot. The Epsilon shutter was said
to
> >be unreliable but mine never played up. Does it have a standard coax
socket?
> >Some had a non-standard socket.  Philip
> snip
>
> Philip,
>
> The Xenar would not have had the coverage nor corrections required
> for aerial photography. The Aero Ektar lenses came along much later
> and were used by the UK for aerial surveys during WWII, probably
> supplied under the "Lease Lend" scheme and came over on Liberty ships
> in the early days. Michael Briggs probably knows  a lot more about
> the history.
>
> In my post I was referring to two main types of lens, the standard
> Xpres and the WA Xpres. These are very different in design and
> intended purpose.
>
> The standard Tessar type design of Xpres lens includes an additional
> element in the rear cell probably to avoid infringing the patents on
> the Tessar design rather than adding huge amounts to the performance
> of the lens.
>
> The WA Xpres is a different design - ie a Plasmat rather than a
> Tessar. The Plasmat is a superior design in terms of correction of
> aberrations across the whole field of coverage and the WA Xpres was
> designed to be used for aerial photography where such accuracy was
> important for survey purposes.
>
> The standard Xpres lenses have a great reputation and I am looking
> forward to trying mine out - it is a brass 13" APO Process Xpress f9
> so is compact and may make a good field lens on the 8x10.
>
> Cheers,
>         Clive
>
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