RE: Slit manufacture

Ellis wrote:

> I have been following this talk on using slits for
> photographs. Could someone
> please tell me in simple terms how to use it and the
> effects you get.
> Many thanks

Imagine a camera made out of a six-inch-long CD holder. At the back
end is a film holder or piece of 4x5 film. Imagine that there are two
CDs, one in the middle of the camera, and the other at the front end.
The CDs are, in reality, made out of mat board with slits placed in
them according to the instructions in Eric Renner's book. There is a
"shutter" in front of the front slit. The shutter could be a slide or
cap of some sort.

Here is a link to a slit image that is a good example to show what
happens:
http://www.mnartists.org/uploads/users/user_3586/9f4d8b6fff2517cc01a52
c9829cb9c27/9f4d8b6fff2517cc01a52c9829cb9c27.jpg
You might have to cut and paste this in two pieces to have it work.

This is a photograph of the astrological female symbol. The subject
was symetrical: a round circle and a cross with two equal lines. The
middle slit was a "J" or cane shape. It gave the overall shape to the
phote. The front slit was a zigzag line looking at a flight of stairs
from the side. It gave the waviness inside the "J" shape.

With the CD case camera, you can move the slits into differents slots
(changes focal length) to get a wide range of results. I enjoy the
empty spaces created by the not full coverage of the negative. Moving
the middle slit forward will make the light cover the whole film
plane.

The rule of thumb I use to determine exposure is to take an incident
reading at f90 at the film's ISO speed and they make an exposure four
times longer (or f128 and two times longer or f180 is just right). It
works out to be a second or two on a bright day.

Hope this helps.

Tom
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Received on Fri Feb 4 09:36:59 2005