RE: Question on image circle and medium form at pinhole camera design

Thanks Phil! It's clearly the first scenario -- the corners are perfectly
clean and black. I suppose I will need to modify the camera some more to get
rid of that slight edge that sticks up.

Much appreciated,
R.J.

-----Original Message-----
From: Philip willarney [mailto:pwillarney@yahoo.com]
Sent: Tuesday, November 12, 2002 3:00 PM
To: pinhole-discussion@pinhole.com
Subject: Re: [pinhole-discussion] Question on image circle and medium
format pinhole camera design

--- "Fox, Robert" <RFox@aarp.org> wrote:
..snip..
> Question: my images are all circular, cutting off
> the corners cleanly of
> the square print. Is this because the image circle
> is too small for the
> film? I'm wondering if the circular edge of the
> front plate is being picked
> up on film, since the edge sticks up about 1/4 inch.

If the edges of the photos are sharp, hard edges, it's
probably vignetting -- something in the light path
from the outside world to the film is blocking the
light. So you're getting a nice clean photo of the
edges of the lens holder, for instance.

If the edge is a slow fade from picture to dim picture
to black, then it's falloff. Pinholes as such don't
have an image coverage circle -- the edges just get
dimmer and dimmer as they get farther from the pinhole
and get less & less light.

I think. Any quibbles, anyone?

-- pwillarney@yahoo.com

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Received on Tue Nov 12 15:04:45 2002