[LargeFormat] assignment: Portrait

[Richard Knoppow]

----- Original Message ----- 
From: "LNphoto" <LNphoto@twmi.rr.com>
To: <largeformat@f32.net>
Sent: Monday, December 01, 2003 8:38 PM
Subject: Re: [LargeFormat] assignment: Portrait


>
> On Monday, December 1, 2003, at 10:41  PM, Richard Knoppow
wrote:
> > wrote:
> >>
> >   The spring tenstion can be adjusted. I am not sure if
the
> > Press-Graflex works like the Series-B and Series-D, and
> > Speed Graphics, but in all three its possible to wind
the
> > resting tension of the spring by removing the screws
holding
> > the plate of the tension adjustment knob and turning the
> > whole thing.
>
> <snip> I'll give that a shot, I certainly don't see where
I need the
> upper speeds, never used the 1/1000 on a Speed Graphic
yet, don't know
> why or how I'd use 1/1500.  I suppose with 400 speed film
and a Ic
> Tessar....
> But I didn't notice that I can't get the spring to get as
low as
> tension #1.  The tension numbers are odd (appropriate for
an F&S
> camera) and run from 1 to 15.  So I may do some fiddling
but I'm gonna
> try shooting it as is first..
> >   The spring also probably needs some lubricating, you
can
> > squirt some light machine oil down the inside of the
tube.
>
> Not sure what you mean by "tube". All of my clock repair
buddies prefer
> graphite powder on their springs.
>
   Graphite should NEVER be used on a camera anywhere. It
probably shouldn't be used on clocks either.
   The tube is the one containing the main spring. It is
also the tube around which the lower end of the shutter is
wound.
   Once you take the back off the camera you will see some
of the FP shutter. I can probably walk you through some of
the disassembly but the Press Graflex shutter is a little
different than those found in the B,C,D versions.


> >   Note that Graflex shutters do not match the speeds on
the
> > chart except in a a few places. The highest speed is
very
> > optimistic and if tensioned up to make it actually the
> > listed speed, the lower speeds will be off.
> >   Also note that measurement of focal plane shutter
speeds
> > must be done carefully. Despite the popular wisdom to
the
> > contrary FP shutters are not very efficient. The
effiency
> > varies with the ratio of slit width to distance from
shutter
> > curtain to film and with the angle of the cone of light
from
> > the lens. In general, the shutters are more efficient
for
> > long focal lengths and small f/stops. Since the marked
> > speeds are based on average efficiency measurements of
total
> > open time will show slower speeds the same as with
between
> > the lens shutters.
>
> So what's the best way of testing this flivver? i have a
Calumet
> digital shutter tester.
> Can't I just stick it up next to the shutter without a
lens and a nice
> 40w lamp at the other end?
> After all, the tester will show what that area of the film
got for an
> exposure, won't it?
> Granted I'd have to test multiple spots multiple times to
see any trend
> of under exposure at the bottom, but won't that get me in
the ball park?
>
> How should it be done?
>
  Get a Calumet shutter tester. These are now somewhere
around $100, still worth every penny.
  For focal plane shutters the method is to set up a light
source and back away from it until the speed tester no
longer registeres the light. Then move to 0.7 this distance.
This is simply the distance at which the intensity of the
light is twice that at cut off. This measures the shutter
speed at the half light points giving the _effective_ speed.
The sensor of the tester is small so that the relative speed
at different parts of the film plane can be measured easily
by moving the tester.
   There is no way of evening out the exposure but its
useful to know how much it varies at various settings.
Graflex used to advertise this as a feature since it results
in darker skys in landscapes, at least at speeds using small
slits.
   The effective speeds are closer to the marked speeds than
are total open time speeds. The difference at 1/000th on a
Speed Graphic is nearly a full stop, i.e., almost 2 to 1
speed difference.


> >   Graflex shutter are also not constant speed accross
the
> > film. They tend to accelerate so that the bottom of the
film
> > (top of the image) gets less exposure than the other
end. At
> > the highest speed the difference can be a full stop.
>
> Which is/was good as the old plates were blue sensitive
and over
> exposed the sky.
>
  See above, Graflex advertised this:-)

> >   The story is that Press Graphics were the standard
press
> > photographer's camera until the late 1920's. At that
time a
> > New York Times photographer was killed covering an
> > automobile race because he had is face in the finder
hood
> > and didn't see an on-coming car. The Times said no more
> > Graflex's so there was a fairly rapid switch to Speed
> > Graphics, then a new model.
> >   The story may be apacrophal and I can't remeber where
I
> > first read it but somehow think it was a relaiable
source.
>
> while it might not have been an auto race or the guy at
The Times, I'm
> certain somebody got hurt because they couldn't see what
was around
> them. And even if they did see something coming, this
thing puts you in
> a position that you can't jump very quickly.
> >
  BTW, I happen to be fond of Graflex SLR's for some reason.
I have a 4x5 Super-D which is a little more practical for
fast working because of the automatic diaphragm. However,
the image in the finder is surprizingly bright even when
stopped down. There is an advantage to adding a fresnel lens
to the finder ground glass. If you are lucky you will have
the ground glass back. These were supplied with the cameras.
It fits in like a film holder. Its useful for checking the
adjustment of the finder G.G. and for some other purposes.
  I think Graflex even made a bag type magazine for the 5x7
cameras.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com