Re: 8x10 Macro Pinhole

You wouldn't need more bellows extension, as a pinhole does not need to be
focused like a lens. 300mm is a standard focal length, not wide angle nor
telephoto. You could figure out how large the image would be on the film by
using simmilar triangles. I believe the optimal pinhole for a 12" focal
length is somewhere around f/512 which could lead to evil exposure times
depending on the lighting. Since you're so close to the subject, things
will have to be kept *very* still for long exposures. You might want to use
400asa film and push process it to bump up the contrast (which might help
make it a bit more abstract?) and decrease exposure times.

Where F= distance from pinhole to film, D = distance from pinhole to
subject, S = size of object, M = size of image on the film
F/D = M/S

Hope that helps,
John

----- Original Message -----
From: "M" <fontpro@usa.net>
To: <pinhole-discussion@pinhole.com>
Sent: Saturday, June 23, 2001 4:21 PM
Subject: [pinhole-discussion] 8x10 Macro Pinhole

> Hello!
>
> I want to build an 8x10 pinhole for doing abstract macro photography. I
> was thinking about 300mm for the focal length, being the standard for
> 8x10 lens cameras.
>
> But then i thought 2:1 or higher magnification with a lens camera would
> have a bellow extension of 600mm and more.
>
> So would a 300mm pinhole 8x10 camera for macro work be kind of a wide
> angle?
>
> I'm confused:-)
>
> Mac
>
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Received on Sun Jun 24 00:06:54 2001