I am sure this has been done many times before, and I thought I saw it somewhere online some time ago, but I could not find one so I built one.
If anybody wants to build their own, here is the formula for Excel. Given both the lens focal length in mm (or inches) and angle of coverage in degrees, it will calculate the lens' total available Image Circle in mm (or inches).
Formula for the Image Circle cell is: =2*(TAN((ENTRY CELL LOCATION FOR INPUT OF LENS' ANGLE OF COVERAGE/2)*PI()/180))*ENTRY CELL LOCATION FOR INPUT OF LENS' FOCAL LENGTH.
Example. In my spreadsheet, cell D7 is where I input the lens angle of coverage and B7 is where I input the lens focal length, and the formula is this: =2*(TAN((D7/2)*PI()/180))*B7
Mods: If this is redundant or old news, please feel free to delete it.
Cheers,
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