OHMYGOD! I'm getting a headache!!!! Stop the insanity!!! (chuckle)
Now, I'm am thoroughly convinced that if I doubt my camera's focusing I will
definitely send it to Greg! This is just too complicated. I'll stick to just
refelting the backs.
Gees! I bet there's even more things that have to be considered when using
GG. What about light refraction? Does that 'cause problems? I would imagine
that if it did, it would be so minute that the human eye wouldn't notice.
Because all it does is just bend the light right?
So, it's gone from the front of the GG plane for focus, the middle of the GG
for focus and the back plane. I'm so confused! What do view cameras use? I
was under the impression that it was the back of the glass that is used at
the film plane. No, that can't be right 'cause when you slide the film in
it's in a different place...forget it...I need some aspirin. (chuckle)
However, I still feel it's a neat idea just to see what is being framed when
using a 58/60 mm lens even if it's not in perfect focus.
Ya'll figure it out and then email me some pictures of the setup, maybe with
notes...and a couple of close-up shots...show where the film plane is in
reference to the ground glass...
I'm just kidding. I'm not a tech-y, I just want to take pictures and my Koni
makes some sharp pictures!
I still haven't processed my last roll....(sigh)
You know...I used to be dead-set against using that B&W c-41 process film.
However, in the recent Pop. Photo. magazine (I think that's the mag. I was
reading last night), they did a review of using b&w silver gelatin process
(Ilford) and the b&w c-41 process (Kodak Portra B&W) and it's very
interesting. It seems that at the same 400 speed film, the c-41 b&w film has
a much finer grain than the silver gelatin processed film. However the C-41
b&w processed film is less sharp. Which means that it would be excellent for
portraits. However, the C-41 is not as stable as the traditional b&w film. I
think they showed the differences between a silver gelatin print, versus
some paper that I can't remember (Kodak E???) and inkjet. It's a neat
article and one that I've always wanted to know about. I'll have to reread
it again.
Anyhow, I just thought I'd share this with ya'll. I might actually give that
Portra B&W stuff a try....(why do I hear "traitor" going through my head?)
Barbara
-----Original Message-----
From: Eric Goldstein [mailto:egoldstein@usa.net]
Sent: Thursday, January 17, 2002 9:10 AM
To: Koni-Omega Mailing List
Subject: [KOML] Re: Ground Glass
Evan Ludeman wrote:
> This is done to compensate for the fact that film inevitably bows out
> slightly from the back. It's not much. 0.008" is the number that
> sticks in my mind. It is, however, a fair fraction of the depth of
> focus at f 3.5, so it is non-trivial in that sense. Before I knew
> about this, I had my camera set up to focus in the plane of the film
> gate. I subsequently corrected this and can verify that it does make
> a noticeable difference.
This makes sense. The Koni Omegaflex manual (p. 35) is quite
emphatic that a
piece of gg layed across the film plane will not get you where
you need to
be:
"The special K-O groundglass attachment is mounted on an aluminum frame
which seats into the focal plane of the K-O magazines or K-O cameras.
A groundglass within the frame is of very fine grain
composition and extreme
flatness. It is designed to fit INTO (their emphasis) the film
plane frame
not on top of the film plane frame. The purpose of this is to
assure that
the viewing surface of the groundglass is at the precise plane,
at which the
emulsion layer of the film is seated, when the intermittent
pressure plate
of the K-O roll film holder as it its maximum forward pressure.
It is for this reason that the use of an ordinary groundglass,
which is laid
ON TOP (again, their emphasis) of the film plane frame and
which has as its
viewing surface above the film plane frame, is not suitable for
obtaining
accurate focus with the K-O film and pressure plate system."
It seems Peter that if this explanation is credible that the addition of
your plastic layer is taking you further away from where you
want to be...
Another piece of information I just came across from a fairly reliable
source.. apparently the point of focus on a piece gg is
somewhere BETWEEN
the front and rear surfaces and not at the front surface...
Eric Goldstein
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