Archived posting to the Leica Users Group, 2012/03/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Mar 30, 2012, at 6:34 PM, Robert Adler wrote: > Steve, > If you want to wait until next week, I can tell you if NJ does a good job. > I sent both my M and my Nocti back to have them "mated." Purportedly when I > bought my M and Nocti from the dealer a few months ago, the dealer sent the > Nocti to NJ to have it CLA'd and coded and "brought to specs" with their > standard M9 (not mine). I think you know the rest of that part of the > story. I will get both my M and Nocti back hopefully mid week next week and > can let you know how it is by the weekend. I think I will wait to hear from you Bob, thanks, Steve > Best, > Bob > > On Fri, Mar 30, 2012 at 4:43 PM, Marty Deveney <benedenia at gmail.com> > wrote: > >> On Sat, Mar 31, 2012 at 6:00 AM, Richard Man <richard at >> richardmanphoto.com >>> wrote: >> >>> I think the proper terms is back focus. >>> >> >> "Back focus" gets used all over the internet for everything from out of >> spec equipment to focus shift. Steve's lens is not adjusted to factory >> specs. >> >> >>> If the focus point changes as you change the aperture, then it's focus >>> shift and you are stuck. You can then decide to calibrate to an aperture >>> that makes the most sense to you, usually at wide open and hope the DoF >>> will cover for any errors in narrower aperture. >>> >> >> If you have genuine focus problems wide open the problem is not focus >> shift. >> >> The focus point of the Noctilux shifts substantially when stopping down. >> As Leica adjusts this lens when correctly focused the plane of optimum >> sharpness for a Noctilux is slightly (very slightly) in front of the point >> you focus on. Then as you stop down the focus point shifts back, mostly >> within the plane of sharpness offered by increased depth of field. You >> can >> get Leica to adjust the lens to focus correctly at f1 but then focus shift >> means that your focus will be off until f5.6. I got mine adjusted this >> way >> because I always carry an f2 50mm lens when I carry my Nocti, so it >> basically gets used at f1 or not at all. >> >> Your lens and camera(s) need to be adjusted to factory specifications and >> tested together. You need specialised equipment to do this. >> >> >> >>> I believe this is one of the reasons why the Nocti /0.95 was created. >>> >> >> And because some of the special glass in the f1 ran out and more couldn't >> easily be manufactured. >> >> >>> You should test out whether it's focus shift. Just put the camera on a >>> tripod and photograph a yard stick at an angle. Take multiple photos >>> without changing the focus but only the aperture. >>> >> >> This is good advice, but the first thing to do is to do some really >> critical wide open focusing to see where the point of optimum sharpness is >> relative to the focus point. If this is off, then there's no point >> worrying about focus shift; you know it's there. >> >> Marty >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > > > -- > Bob Adler > Redwood City, CA > http://www.rgaphoto.com > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information