Archived posting to the Leica Users Group, 2012/03/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Over the years, since I started with the M8 and now with the M9, I've found four lenses that worked OK with film that needed "tightening up" focus wise. I sent them all to DAG and with the exception of the C/V 28/1.9 that he says he could not adjust, I've been really happy with the result. I did not send the camera. When I was in TV news, we routinely sent new Angenieux zoom lenses for collimation on CP16 cameras. On Sat, Mar 31, 2012 at 3:53 AM, Steve Barbour <steve.barbour at gmail.com>wrote: > > 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 > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > -- Regards, Sonny http://sonc.com/look/ http://sonc-hegr.tumblr.com/ Natchitoches, Louisiana USA