CCBaggett@aol.com
Date: 04/12/02-06:30:41 PM Z
The Black Cat Pinhole Exposure calculator can be purchased at
www.pinholeresource.com for $22.00
Cheers,
Charlie Baggett
In a message dated 4/12/02 7:30:31 PM Eastern Daylight Time,
dlhbloom@mindspring.com writes:
>
> Hi Shannon,
>
> I don't know anything about that formula. Looks complicated, and I
> don't think it allows for reciprocity failure.
>
> But to answer your other questions . . . the f-stop for a pinhole camera
> is the focal length divided by the diameter of the pinhole. For
> example, if your camera has a pinhole to film plane distance of 5.5
> inches, and your pinhole diameter is .0018 inches (that is the size of a
> #10 hand sewing needle), this ratio is 5.5 divided by .0018, which is
> 300. So 300 will be your f number.
>
> There are optimal pinhole sizes for a given distance (from pinhole to
> film plane), though you don't have to use those. Here's the Pinhole
> Visions site that includes a pinhole calculation guide for optimal
> pinhole sizes: http://www.pinholevisions.org/resources/cameraTable.php
> There's a lot of good information on that site, including a discussion
> list you can join, so check it out.
>
> There are folks out there who have worked out exposure calcuations--all
> based on pinhole size, film/paper being used, and allowing for
> reciprocity failure. Personally, I get used to whatever camera I'm
> using and simply look at the weather and guess. Once I understand how
> my camera works under certain conditions, I can pretty much determine
> correct exposures. However, lately I've been using much larger (more
> expensive) film, so I'm trying to be much more exact. There is a great
> little guide, called the Black Cat Exposure Guide. You can find it on
> the web. It's cheap and light and works great.
>
> Hope this helps.
>
> --Diana
>
>
>
>
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