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

Or you could attach the pinhole right to the front of
the camera, on that edge part! I've found converting
a couple of cameras to pinhole that a pinhole "sees"
things a bit differently than a lens does -- so a
pinhole installed in the same place the lens
originally was will sometimes vignette, even when the
lens didn't. So you try it and find out, just like
you're doing...

-- pwillarney@yahoo.com

--- "Fox, Robert" <RFox@aarp.org> wrote:
> 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 15:14:46 2002