Archived posting to the Leica Users Group, 2010/11/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I agree, however DOF of a 21mm covers up inaccuracy in focusing.....which is essentially what a too thick or too thin mount would do to/for you..... I do not understand why " mount precision gets greater with wide angle lenses, not less, since a given axial error is a bigger proportion of the focus travel." Can you explain to me ? Frank Filippone Red735i at earthlink.net -----Original Message----- From: lug-bounces+red735i=earthlink.net at leica-users.org [mailto:lug-bounces+red735i=earthlink.net at leica-users.org] On Behalf Of Frank Dernie Sent: Thursday, November 25, 2010 12:18 PM To: Leica Users Group Subject: Re: [Leica] 6bit coding Hi Frank, it is not the depth of field which is important for the focussing register, but the focussing travel. The importance of mount precision gets greater with wide angle lenses, not less, since a given axial error is a bigger proportion of the focus travel. I am sure someone on the list has the data but IIRC the axial focus travel for a given change in distance is proportional to the focal length, so a 21mm is about 2.5 times -more- sensitive to an axial error than a 50mm lens. cheers, FD On 25 Nov, 2010, at 18:35, Frank Filippone wrote: > It made no difference to my 21.... but then again, my DOF is a "bit" > more relaxed..... _______________________________________________ Leica Users Group. See http://leica-users.org/mailman/listinfo/lug for more information