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primus96 · Joined: 13 Nov 2003 Posts: 225

I have heard of a formula to paste in a spreadsheet that lets you calculate the image circle from the focal length and the coverage in degrees.
I am sure I heard of it through this forum.
Anybody got any idea?

Dan Fromm · Joined: 14 May 2001 Posts: 2165

Quote:

On 2006-05-12 14:04, primus96 wrote:
I have heard of a formula to paste in a spreadsheet that lets you calculate the image circle from the focal length and the coverage in degrees.
I am sure I heard of it through this forum.
Anybody got any idea?

Hmm. Didn't you have to learn trigonometry in school? Have you no resources of your own?

Diameter of circle covered = 2* tan(angle/2) * focal length. If you're using Excel, its tan() function wants the angle in radians, so you want tan(radians(angle in degrees)).