On Apr 1, 2005, at 8:18 AM, J. C. O'Connell wrote:
Anybody knows how to calculate lens hood exit diameter if hood length and lens angle of view are known ?
I have a hood calculator program I wrote in excel. It
calculates length of hood knowing: film format, lens focal length, front
element diameter,
front of hood diameter. I can send it to you via email if you like,
just request hoodcalc3.xls file.
I'd like to see that.
Since I am only using the 16x24mm format, I just pick lens hoods targeted at the 35mm equivalent FoV focal length lens. It's simplistic but it seems to work fine. Most manufacturers' hoods are pretty conservatively sized to prevent against vignetting: a standard lens hood designed for a 50mm lens on 35mm film works fine on an A24/2.8 with the DS, for instance.
Godfrey
