[LargeFormat] 90mm Schneider f5.6 Super Angulon vs f8

[mark blackman]

I must admit, I did not think of this with the ebony Fresnel, nor was there
any warning. Field tests show no problems, and as I'm sure you know focusing
with a 90mm lens on close (10 feet) items is quite critical. In my humble
opinion, the extra fresnel magnifies the image on the GG, so one does not
need to make allowances.
----- Original Message -----
From: "philip.lambert" <philip.lambert@ntlworld.com>
To: <largeformat@f32.net>
Sent: Monday, April 07, 2003 7:33 PM
Subject: Re: [LargeFormat] 90mm Schneider f5.6 Super Angulon vs f8


> Understood but if the fresnel screen is fixed to the rear of the ground
> glass without displacing it forward the plane of focus might be unchanged.
I
> attached  a fresnel screen by its edges on the back of a ground glass with
> instant glue and maybe I could try attaching a screen by its edges on the
> front of the glass.  The question remains does the plane of focus change
and
> experiments need to be done.  I have a Century Graphic that reached  me
with
> a fresnel on the front of the screen which pushed the glass backwards and
> when I compared that one with a plain CG back there was a distinct
> difference.  PL
> ----- Original Message -----
> From: "Jim Hemenway" <jim@hemenway.com>
> To: <largeformat@f32.net>
> Sent: Monday, April 07, 2003 5:59 PM
> Subject: Re: [LargeFormat] 90mm Schneider f5.6 Super Angulon vs f8
>
>
> > It has to do with the surface which is used for focusing, being at the
> > same plane as the film will be when it's in the filmholder and in the
> > camera.
> > --
> > Jim - http://www.hemenway.com
> >
> >
> >
> > "philip.lambert" wrote:
> > >
> > > Very interesting.  I must experiment and see if the point of focus
> changes.
> > > I have two old SP Graphics and will see what happens. PL
>
>
>
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