Archived posting to the Leica Users Group, 1998/04/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thibault Collin wrote: >Of course, but if we have free time this summer, we could try to calibrate >it with other lenses which will give other apertures!! It would be a tough >job! Thib: What an interesting idea! I don't know if I'll get around to doing anything about it, but I think the theoretical answer would be as follows: Two stops slower for twice the focal length. Therefore (approx.): 50mm= f:5.6/f:16 75mm= f:8/f:22 90mm= f:11/f:32 135mm= f:16/f:45 I stand ready to be corrected by LUG optical wizards. Remember I did say approximate, and DOF is a tricky issue which can (and has) filled whole books. Nick Hunter