-> My methods have been a la the Hole Thing, involving brass shim
-> stock (.002"?) and twirling a needle and filing successively on
-> back and front. Questions:
-> - Also my experience has shown that there is an optimal
-> hole size, (no measurements; i don't have access to a
-> microscope) and if I try to make a hole smaller, the image
-> i get is suddenly fuzzy. Is this diffraction, or just
-> imperfect hole results?
For those having no microscope, you can check the quality and size of a
pinhole by proyecting on an enlarger easel an image of the hole (mount
the hole on a slide mount, for instance), focus the hole using your
grain focuser and check the quality of the hole. Also, measure the
size of the hole (dot) on the easel. Without moving enlarger head,
proyect some other opening of known dimensions and measure its image
size on the easel, then calculate the enlargement factor, once this is
known apply that factor to the image size of the hole and you'll know
the size of your pinhole with more accuracy than it is needed (at least
for pinhole photography).
I just made a new pinhole, its proyected "image" was 2.75mm. I then
proyected an opening 2mm wide (that was the rectangular holes at the
side of 35mm film) and its image was 22.5mm on the easel, this tells me
the enlargement factor was 11.25 (22.5/2) then, by dividing the
image size (diameter) on the easel of the proyected pinhole (2.75mm) by
this enlargement factor I obtained the size of the pinhole.
Pinhole diameter= 2.75mm/11.25 = 0.2444mm
The more you raise the enlarger's head the easiest will be to take all
the measurements and therefore more accuracy will be obtained.
The same principle can be applied when using a slide proyector.
I understand this is known to the majority, if you are one of them pls
disregard this MSG.
Guillermo Penate
* 1st 2.00b #2045 *