One of the reasons that 'ground down dimple' holes seem to work best, I
believe, is because a sharp edge to the hole improves the image (reduces
diffusion or diffraction - I can never remember). Thus, a hole in thin
material with no burr is better than a drilled or laser cut hole in thicker
material, although precise hole size is difficult.
Pinhole should be making a comeback, now that we can simply scan and
reverse a paper negative.
Andrew
> Dear all, Regarding pinhole photography,
>I have found 2 methods that work well with pupils in school. Method
>1.....Grind the end off a small sewing needle using an oilstone. Place
>an aluminium strip, pie-dish? on a hardwood block, place needle on
>strip and tap with a small hammer. The aim is to punch out a small disc
>of aluminium rather than to pierce a hole with a point. Attach to
>backing and spray with matt black paint. With care, and using thin
>material good results can be obtained. Use safety glasses!!! Needles
>are highly tempered and can snap. Method 2......Using a cylindrical
>tin punch a dimple from the inside using an engineers punch. The aim is
>NOT to pierce the can but to raise a dimple which can then be stoned
>down using an oilstone. A very good result is possible using this method.
>
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