Re: ? and 4 x 10 point and shoot

Pete Bergstrom (bergstro@src.honeywell.com)
Thu, 29 Jun 95 18:35:29 CDT

>>>>> On Fri, 30 Jun 1995 08:59:54 +1000, Donald Nelson -FT-~ <dnelson@sedona.intel.com> said:
>> Don described it well - the one we've seen is slightly smaller than an
>> ordinary shoebox, made out of plywood (probably at least 3/8 inch thick)

> Come to think of it, wouldn't the thin, strong, model aircraft-grade
> plywood be quite adequate for most of the sides of such a box? This stuff
> is widely available in most model airplane-oriented hobby shops in sizes
> and thicknesses that would be quite adequate. Just paint the inside
> black to eliminate all light leakages (and watch for any minor splits, etc)
> It would be lighter than using commercial (building) grade plywood.

I bought a 3/16" sheet a few months ago to make lensboards with and found
that it was very difficult to get a nice flat piece. It was OK for a 4x4"
section, but I'd want a little thicker material (perhaps two sheets glued
face to face might work) in order to get the right parallel and
perpendicular surfaces. (I did pick through the entire bin for the choice
material.) One important thing - the quality of the wood (birch, maple,
etc) in the aircraft-grade plywood will almost certainly be much better
than building-grade material.

Thinking about it a little further, as long as the lens axis is
perpendicular to the film plane, it doesn't matter how bowed the sides of
the box might be.

>> with a lens on one side and the ground glass on the other. Placing the GG
>> such that when the film holder is inserted it is correctly oriented is
>> probably the hardest part of the whole thing.

> Actually depth of focus from gg to film plane is harder than orientation.
> Talks with Canham indicate that this machining is the major expense in
> making the cameras. (and its is dependent upon the holders for sizes >8x10!!!
> as there is no ANSI standard).

You're correct - when I said orientation I meant placing the GG such that
it accurately represents the film plane while focusing.

Pete