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" <hornpl...@home.com> To: <pinhole-discussion@p at ???????> 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 > > > _______________________________________________ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ >
