Unfortunately you can't vary the input for focal length in your formulas, which is the whole point to comparing different AOVs of particular focal lengths on different formats. It's complicated by the fact that different nominal focal lengths in fisheye lenses give equivalent results. Just in Pentax we have 3 full frame 35mm format fisheye lenses with different focal lengths, (M42 Takumar 18mm f11, [K]17mm f4.0 A 16mm f2.8, not to mention the fisheye zooms), each delivering ~180º diagonally, and ~110º horizontally. The image mapping is anything but linear, which makes AOV calculations for different formats approximate at best. However based on experimentation and known lens focal lengths You can compare lens coverages on other formats, (but not AOV). For example, a 17mm lens is the equivalent of a 35mm lens on 6x7 and behold Pentax made a 17mm fisheye for 35mm and a 35mm fisheye for 6x7, 16mm on 35mm is the equivalent of a 10mm lens on the Pentax APS-C sensor digitals, and loh Pentax makes a 10-17mm fisheye zoom for APS-C.
Digital Image Studio wrote: > On 01/09/2007, David Savage <[EMAIL PROTECTED]> wrote: > > >> (Just out of curiosity, what's the formula for fisheye lenses? It >> would be neat if there was a check box for that) >> > > >From a spread sheet I wrote a while back: > > VAOV (in degrees) =image height /(image width^2 + image height^2)^0.5x180 > HAOV (in degrees) =image width/(image width^2 + image height^2)^0.5x180 > > It was my own derivation so be warned ;-) > > -- Remember, it’s pillage then burn. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
