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

[Jim Hemenway]

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
> ----- Original Message -----
> From: "Jim Hemenway" <Jim@hemenway.com>
> To: <largeformat@f32.net>
> Sent: Monday, April 07, 2003 2:40 PM
> Subject: Re: [LargeFormat] 90mm Schneider f5.6 Super Angulon vs f8
> 
> > Philip:
> >
> > In a conversation with Bill Maxwell about a week ago, when discussing a
> > fresnel screen for my 11x14, he told me that the fresnel would have to
> > be used on the back of the groundglass, that is to say on the
> > photographer's side of the groundglass.  If used in front of the
> > groundglass the focus will be wrong... unless the wooden frame is routed
> > to a different depth so that the fresnel will be positioned to be where
> > the groundglass had been previously.
> > --
> >
> > Jim - http://www.hemenway.com
> >
> >
> >
> > "philip.lambert" wrote:
> > >
> > > I am not using a Beattie screen as in the UK such a 5x4 screen is
> absurdly
> > > expensive. The ground glass has the 2x3 format coated with a v.thin
> deposit
> > > of vaseline with a fresnel on top.  Not bad. I had a Boss screen on my
> 69
> > > Linhof which was good and then I bought one with plain etched glass that
> was
> > > just as good. Odd.  I've been told to try the fresnel on the underside
> as
> > > that way the circles are less obvious but I would presumably have to
> trim
> > > and fix it to the glass surface with adhesive at its edges rather than
> > > displace the focussing glass outwards.  I think the oldfashioned black
> cloth
> > > is called for.  But some of the lenses I have collected are f3.5 or f4.5
> and
> > > it makes a real difference. PL
> > > ----- Original Message -----
> > > From: "Vince Dobson" <manitec@bellsouth.net>
> > > To: <largeformat@f32.net>
> > > Sent: Monday, April 07, 2003 1:06 AM
> > > Subject: RE: [LargeFormat] 90mm Schneider f5.6 Super Angulon vs f8
> > >
> > > > Are you using a Beatti intescreen?  After replacing mine with one, I
> no
> > > > longer long for a lower F Stop lens - my F8's and F9's are plenty
> bright
> > > > enough now - This would be a much cheaper alternative.
> > > >