RE: Pinhole and SLR

[Wayde Allen <allen@xxxxxxxxxxxxxxxx>]

On Fri, 30 May 1997, Joe Berenbaum wrote:

> I should apologise for not making this clearer- my suggestion of a pinhole
> between the film rails was a joke! I used a ;-} but maybe I should have made
> it more obvious.

No need to apologize, I simply didn't read carefully enough.  I seem to be
doing a lot of that lately <grin>.

> What I'd like to try sometime, ideally on a view camera so that there would
> be no problem with a reflex mirror hitting it- is making a pinhole that
> could come quite close to the film plane- much closer than a pinhole mounted
> on an SLR body cap could. It would be on bellows and so in theory I'd have a
> zoom pinhole.

I've got a small pinhole camera built using a 35mm film can.  I simply
punched a hole in the side, and put a piece of black electrical tape over
that to use as a shutter.  This gives a fairly short focal length pinhole,
and a curved film plane to boot!  It works, but I need a smaller hole to
try and improve the resolution.  Developing those little snippets of film
is kind of a pain too.

I also have thought about building a "zoom" pinhole.  I've just got to
finish the 4x5 field view camera I'm working on now.  Actually, all I
should have to do is make a lensboard with a pinhole.  I've also thought
about using telescoping tubing, or even a piece of threaded pipe for such
a design.  After all, there shouldn't be any need for swings or tilts, so
the only dimension that needs to change is the film to pinhole distance. 

> Then I could check the coveage indoors with some high
> intensity lights and calibrate it so I have an idea what it covers at what
> bellows extension, and then just use a separate viewfinder of some sort for
> framing the picture in normal light levels. Well it's an idea...

I've been thinking about working out the mathematics for the image circle
of a pinhole.  Has anyone on the list already done this?  Maybe some day
when I have the spare time????  Measuring is certainly a possibility. 

- - Wayde
  (allen@xxxxxxxxxxxxxxxx)


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