Re: Pinhole and SLR

[Wayde Allen <allen@xxxxxxxxxxxxxxxx>]

On Fri, 30 May 1997, Joe Berenbaum wrote:

> altering the bellows extension -efffectively a zoom. Thus a way to assess
> the angle of view other than a single fixed finder (and other than by
> looking at the extremely dark ground glass), would be useful.

Following on the heels of my last post, I was just thinking that one could
likely get an estimate of the field of view from the angle formed by two
lines drawn from opposite corners of the negative, and intersecting at the
pinhole.  If you extend these lines through the pinhole, the resulting
angle should be the maximum field of view recordable by the film (I
think). 

Lets see, that would make the angle something like:

    angle = 2 * arctan(s/f)

    where:  s = diagonal/2
            f = film to pinhole distance

Please correct me if this is wrong.  I'd like to better understand it.

Thanks,

- - Wayde
  (allen@xxxxxxxxxxxxxxxx)


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