Re: Variable Focal Length Pinhole

I've found that a pinhole has a "range" of optimum sharpness.
My 450 micron that I use on my 4x5 is best in the range of 90 to 180mm.
Not a whole lot of difference in that range.
It suffers but doesn't do too bad even out at 270mm (f/600)
One pinhole calculator says it is optimum for 5500 Angstroms102mm and
another 150mm. ??
It is really subjective in "wide bandwidth" mode, i.e. color or B&W with no
filter.
If one shoots narrowband B&W, e.g. use a 25 or 29 filter, then the focal
lengths are shorter for that pinhole (or the diameters are bigger for a
given focal length) and the "zoom range" is narrower if you are looking for
optimum sharpness.

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Received on Fri Jul 30 19:57:22 2004