Calculate the diameter of each f stop at the original focal length-probably
40 or 50 mm. Diameter equals focal length divided by f stop number. Then
divide aperture diameter into your new lens to film distance to get the new
f stop. You undoubtedly won't get full coverage of your new format with that
lens but it should be fun anyway.
----- Original Message -----
From: "John Putnam" <hornplyr3@home.com>
To: <pinhole-discussion@pinhole.com>
Sent: Wednesday, October 24, 2001 2:16 AM
Subject: [pinhole-discussion] 12x18 w/35mm lens
>
>
> Hi All
>
> I am building a large "mammoth" Camera, 12x18, And I have A lens for a
argus c3 that I was going to use as my lens. but I know that the f-stop
relates as the distance from the hole to the film Plate. So if the lens says
F5.6 for 35 mm that would but much smaller for my
> 12x18 format and I need this equation so I can use the C3 lens and write
the new F-stops on it. IF anyone has any help please let me know.
>
> John
>
>
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>
Received on Wed Oct 24 16:25:02 2001
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