Covering Power of Pinholes

Hello!

New to the list and this is my first post.

A little background.....

I have been doing photography for 6 years, and currently shoot 4²x5² w/ a
Cambo Legend monorail and 6x7 with a Koni Rapid 200. Most of my experience
has been with conventional silver printing, but I have tried cyanotype & gum
bichromate in the last 6 months, and am going to plunge forward into various
alt processes as I can.

I really want to try pinhole next, and want larger negatives for contact
printing. I¹ve found some interesting info on the web and will build my own
camera & pinhole very soon. One thing that I am confused about is
determining how much covering power a given pinhole has. Is it just
relative to the distance of the pinhole to film/pinhole dia., which then
determines the ³focal length²? Forgive me, I struggle with comprehending
even the most basic concepts of optics generally, and am no better with
pinhole.

I¹d like to try say an 11²x14² format, or perhaps a panoramic 8²x16². The
wide-angle possibilities (both the really wide & moderate) are in my sights
first and I like distortion, but not to the point of monotony. I am looking
to use sheet Lith film developed in dilute developer, or pyro; and will be
making my own film holders and back to be able to do multiple exposures.

Could someone enlighten me how to figure out the proper pinhole size &
lens-to-film distance for the aforementioned formats? I understand that a
curved film plane is employed to compensate for light fall-off. Is the
optimum curve determined by experience, or are there known combinations?

I haven¹t found any books that focus on specifics. Eric Renner¹s book
apparently focuses on the history more than construction, which is the
opposite of what I want to learn first. Perhaps someone could recommend more
literature because the web only seems to offer an overview of pinhole.

Lastly, Larry Bullis¹ excellent article on pinhole construction mentioned
using silver sheeting & a microscope to make pinholes. I¹d actually like to
try both of these methods. Does anyone work in this way? Where do you get
the silver sheeting and what kind of microscope do you use? Precision
pinholes seem to really effect the resolution, quite appropriate for certain
shots (although the softness is perfect for others).

Thanks.

-Joe
Received on Thu May 30 23:47:10 2002