Re: 4 x 5 questions

I ran into this problems with a Finney 4x5 camera.

Basically, you can forget about composing on the ground glasss.
Well, supposedly, if you have a large pinhole, you can wrap a black
cloth around your head, and you might be able to block out enough light
to see a faint image on the glass.

Best thing to do is to mentally project "lines" from the corners of your
film, on the camera back, extending through the pinhole out into space.
Those lines will represent the edges of your picture.

It is a low tech approach, but, hey, we're talking pinhole here! You
will be amazed at how accurately you can compose this way, with a little
practice. To help me do this, I have made very tiny notches on the
corners of my film plane, on the camera back, and very tiny notches
on the top and sides of the lens board, to aid in projecting this "line"
into space.

You may or may not be able to see this diagram!

Top view looking down on camera. F line is the plane. B is area inside
your bellows. P is pinhole, with lines extending in the space. Stick man
is your beautiful model (I have to much time on my hands today).

        F
                      /
        |\ /
        | \ /
        | \ / O
        | B }P \+/
        | / \ ^
        | / \ / \
        |/ \
                      \
        F

On Mon, 17 Sep 2001, Chris Harris wrote:

> I recently bought a 4 x 5 Tachihara camera and fitted it with a zone plate.
> I've been using zone plates on hand built cameras for several years. Large
> format photography is new to me. So far I've been fiddling with the camera
> and reading a considerable amount of literature on how to use it (for
> example, Steve Simon's book). I have quickly encountered two troubling
> aspects of the using the camera.
>
> First, I can't see the image without a lupe. This makes composing on the
> ground glass impossible. The ground glass is whatever ships as standard
> equipment with the camera. Must I 1) upgrade the ground glass to a Fresnel
> (will this solve the problem?), 2) buy and use a comparable real lens to
> compose (a very expensive choice), 3) check my composition with Polaroids
> (an expensive alternative)?
>
> I should mention that I'm used to pinhole cameras without viewfinders, but I
> thought I'd have the luxury of seeing an image on the 4 x 5 ground glass.
>
> The second problem is that the camera seems to be in focus through a wide
> range of focal lengths. I can't see any difference between the focus quality
> at 150mm (which the zone plate is designed for) and, say, 170mm. The
> magnification changes, but the focus stays the same. I can set the focus at
> infinity by measuring the distance from the film plane to the zone plate.
> However, the fine adjustments of focusing with tilts and swings seem at this
> point impossible.
>
> I'd appreciate your help.
>
> Chris
>
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Received on Mon Sep 17 14:41:14 2001