The sigma is GN 50m @ 100ASA, 105mm zoom reflector setting. The Pentax one is GN 54m @ 100ASA, doesn't say what zoom that's at.
If you multiply by 3 do you roughly get your guide numbers in feet?
Butch
- metrics question Butch Black
- Re: metrics question William Robb
- Re: metrics question P. J. Alling
- Re: metrics question David Savage
- Re: metrics question Butch Black
