Archived posting to the Leica Users Group, 1998/05/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]David, Being new to Leica and rangefinders, this leads me to ask the question: does this mean that I can assume that a high percentage (most?) of my shots with the Summilux 75mm/1.4 will be erroneously focused when wide open? Nathan David Morton wrote: > Shawn London wrote: > > > Erwin Puts calculated the theoretical maximum f/stop at which accurate > > focusing could be possible on the M6 quite a few months ago. I do not > > have the email saved, but I do remember that at 50mm the normal M6 > > rangefinder is accurate enough for an f/.85 lens or something of that > > sort. At least at 50mm, you are quite within the capabilities of the > > regular M6 with a Noctilux. > > Here it is: > > -----------------------------------SNIP----------------------------------- > > There is a mechanical/optical relationship between the accuracy of the > rangefinder and the baselength in relation to the maximum aperture/. > The equation will be published elsewhere, but here is the result: > > Focal length Max aperture Max aperture > M3 M2, M4, M5, M6 > 21 mm 0.12 0.15 > 28 mm 0.21 0.26 > 35 mm 0.33 0.41 > 50 mm 0.67 0.84 > 75 mm 1.5 1.88 > 90 mm 2.17 2.71 > 135 mm 4.88 6.1 > > This equation then tells you that the 21 mm can be reliaby focused when > the > maximum aperture is f/0.12 (incredible!). > At 50mm the Noctilux approximates the theoretical maximum values when > attached to the M6. > The 135mm seems to be overstretched when used at its maximun aperture of > 2,8. > Hope this info has some value > Erwin > > -----------------------------------SNIP----------------------------------- > > David Morton | "saepius ventis agitatur ingens > dmorton@journalist.co.uk | pinus est celsae graviore casu > Islington, London, UK | decidunt turres feriuntque summos > (+44) 171 272 8908 | fulgura montis." (Horace)