Re: Pinhole and SLR

[Joe Berenbaum <joe-b@xxxxxxxxxxxx>]

At 18:44 30/05/97 GMT, you wrote:
>| ... making a pinhole that
>|could come quite close to the film plane- much closer than a pinhole >|mounted
>|on an SLR body cap could. It would be on bellows and so in theory I'd >|have a
>|zoom pinhole. Then I could check the coveage indoors with some high
>|intensity lights and calibrate it so I have an idea what it covers at >|what
>|bellows extension, and then just use a separate viewfinder of some sort >|for
>|framing the picture in normal light levels. Well it's an idea...
>
>If you used a Speed Graphic and mounted the pinhole diaphragm on a
>regular Graphic lens mounting board, the sports finder should show you
>what it will include, no?

I may be totally mistaken, but I thought that the pinhole's effective focal
length varied with distance from the film plane. If so, the bellows would
give quite a variety of focal lengths from the one pinhole simply by
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.

>Sounds intriguing.  Maybe I'll drag the Speed Graphic out of mothballs
>for the first time in years...
>Bob Long
>(boblong@xxxxxxxxxxx)

Well if you do, let me know if it zooms!


Joe B.

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