Optimal pinhole size question - theoretical & practical

I have read Eric Renner's Pinhole Photography on optimal pinhole size
theory and examined the table on pinhole calculations. My question
is more practical than theoretical, though some explanation of theory
might not hurt.

Renner notes (p. 117): "If the pinhole is too large for the focal
length, the image will be blurry. If the pinhole is very, very
small, the image will also be blurry." It's the "very, very" that I
wonder about.

Zero Image cameras use the following:

        Zero 2000:
                Focal length: 1" (25mm)
                Pinhole size: 0.0079" (0.2mm)

        Zero 6x9 Multi Format
                Focal length: 40mm
                Pinhole size: 0.17mm

That is, the Zero 2000 pinhole size is about "optimal." But the Zero
6x9 is considerably smaller than "optimal," closer to a "recommended"
size for a 20mm focal length. I believe that Zernike Au has said
that he used the smaller aperture because tested out sharper.

My practical question has to do with several extra small size
pinholes that I bought in a set from Pinhole Resource (such as .150mm
and .220mm sizes). Aside from lengthening exposure times, would
using small size pinholes on cameras with focal lengths of twice the
"optimal" focal length be any less sharp?

Comments, ideas, experience?

Thanks,

Tom

 
Received on Sun May 5 15:16:11 2002