Archived posting to the Leica Users Group, 2007/09/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Bob, I used the Leica Forum procedure as well but I was more rigorous than you were (and the forum) in the following two areas. 1. I did not use a flat target against the wall. That just tells you if you are in focus or not and not what the DOF is after each adjustment. I lined up about 20 CD's in their holders and positioned about 45 degrees to the film (sensor) plane of my M8. I also placed a 12" ruler in front of the CD's and focused at the 6" point on the ruler. It looked like this: http://tinyurl.com/3dtys4 2. After every adjustment I took 3 photos, wide open, closed two stops, closed 4 stops. This way I would know if there was any focus shift. I also used 7 lenses and took the 3 shots with every lens after each adjustment.. The lenses I used were the 50mm Noctilux, 75mm and 50mm Summilux, 50mm Summicron, 90mmAA and 90mm macro and 35mm Summicron. This exercise was performed over two day and took over 8 hours to complete. I believe the adjustment was made 4 or 5 times in order to get it right with all of my lenses. That's about 100 photos total. The three lenses that were off the most were the Noctilux, the 75 Summilux and the 90AA. The end result was all my lenses are in focus except for the 135mm APO 3.4 at infinity. I don't care about that. I also found that photos look much better if the DOF is centered in front of rather then behind the target focus point. As an example if I take a tight portrait wide open and focus on the eyes, the nose will be in focus and the hair out of focus. That is my preference. Len On Sep 1, 2007, at 1:12 PM, Robert Rose wrote: > Vick, > > The original idea to do this came from the Leica Forum. Look there > if you want to find a more rigorous approach to the problem. > > Bob > > On Sep 1, 2007, at 4:33 AM, Vick Ko wrote: > >> Okay, now I understand. >> >> You are adjusting the RF arm. I anticipate that it only takes a >> very very >> small amount of adjustment. If the adjustment is large, then you >> will end >> up affecting the infinity alignment of the RF image. >> >> Congratulations on discovering this method. >> >> regards >> Vick >> >> -----Original Message----- >> From: Robert Rose [mailto:robert.rose@mac.com] >> Sent: Saturday, September 01, 2007 2:33 AM >> To: Leica Users Group >> Cc: vick.ko@sympatico.ca; Leonard J Kapner >> Subject: do it yourself back-focus adjustment..." >> >> Vick, >> >> We had a thread on this around March or so. I had posted some >> samples and >> how to do it at: >> >> http://gallery.leica-users.org/v/rjrose/focus/ >> >> Bob Rose >> > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information