Re: 35 mm pinhole camera

----- Original Message -----
From: "Zami Schwartzman" <zamish1@netvision.net.il>

> the buurs on the oposit side had to be very carefuly treated with no. 400
> sandpaper to get a perfect hole . Although not a sraight forward job , I can
> get perfect holes as small as 0.05 mm diameter

FYI, such small pinhole would be "optimum" for a camera with a 1.85mm focal
length!! A bit impractical, if you ask me!!

> I experimented with a 0.1 mm hole , got some good close up pictures well
> exposed with Kodak gold 400 ASA( using f: 120 on the light meter ) but the
> results are quite " out of focus " on 10x15 prints .

-Your f/stop should be f/280 and not f/120.
-f/stop is given by dividing the focal length by the pinhole diameter (28/0.1 =
280)
-As pointed out by erickson@hickorytech.net, you should be using a pinhole
0.00784" which is equivalent to 0.2mm. The 0.1mm pinhole is producing too much
diffraction.
-If you want relatively "sharp" 10x15 size results, I would suggest you shoot
medium format or larger.

> I wander if going further to a 0.05 hole will worth the panelty in the f
> number .

Only if you could mount that pinhole about 2mm from the film plane. The
resulting image, BTW, would be a circular image no bigger than some 10mm in
diameter.

> Is there an optimun hole size for best sharpness ? or is it the smaller
> the better.

Take a look to this http://members.rogers.com/penate/pinsize.htm

Guillermo
Received on Sat Oct 12 09:06:09 2002