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Re: [OM] Body Cap with a hole, is pinhole "lens"?

Subject: Re: [OM] Body Cap with a hole, is pinhole "lens"?
From: Jim Brokaw <jbrokaw@xxxxxxxxxxx>
Date: Sat, 31 May 2003 18:44:25 -0700
If you search on the web you can find sellers of 'laser-cut' pinholes... a
small disk with a laser burned hole optimized for pinhole photography. I
suppose you could mount this in a body cap, or probably more effectively use
a lensboard for a view camera...
-- 

Jim Brokaw
OM-'s of all sorts, and no OM-oney...




on 5/31/03 4:46 PM, Moose at olymoose@xxxxxxxxxxxxx wrote:

> I suspect the fuzziness was a result of a poorly formed and likely too
> large hole. If you check the web resources on this subject, you will see
> how important a very smooth and thin edged hole of proper size is. And
> how relatively difficult such a hole may be to produce. The optics are
> based on diffraction at the edge of the hole (The very thing that causes
> loss of sharpness at very small apertures in lenses!). The bigger the
> hole, the less of the total light is properly diffracted and the fuzzier
> the picture. Since it is the interaction of the light waves with the
> edge of the hole that does the work, the accuracy and smoothness of the
> circle is a very important factor in performance. In theory, the edge of
> the hole should also be as thin as possible, hence the techniques that
> abrade a hole in thin material.
> 
> Moose
> 
> Lama-Jim L'Hommedieu wrote:
> 
>> I made a pinhole camera with the "objective" about 1" from the film plane.
>> 
>> I poked a hole in aluminum foil and mounted it on a cardboard tube (okay, it
>> was a toilet paper roll!)
>> 
>> I made 4 film guides with pushpins, and loaded it with a 90mm stip of Tri-X.
>> It worked but I was only able to make a contact print
>> 24mm x 90 mm.  It's probably just as well because even at that size it was
>> blurry and of course, the cylindrical shape of flat film
>> plane gave me additional distortion.
>> 


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