Archived posting to the Leica Users Group, 2001/11/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Seth - This is actually one of the more interesting bits of Leica trivia posted in some time. Thanks B. D. SthRosner@aol.com wrote: > In a message dated 11/28/01 11:10:08 AM Eastern Standard Time, > eric.calderwood@btinternet.com writes: > > >>I have this DR-Summicron which has its aperture scale and index directly >> > opposite to the distance scale. When mounted on the camera, the distance >> > index is facing up and the aperture index and scale is facing down. >> > >> > Is there a way to rectify this? >> > >> > Dan K, >> > > Dan: > > All of the DR and Rigid Summicrons were matched to individual focussing > mounts when delivered new from the factory. The likelihood is that your > Summicron lens head - the front optical part of your lens - has been mated to > a different focussing mount than the one originally furnished with the lens > when new. All DR Summicrons had (and have) an exact focal length of 51.9 mm. > The Rigid Summicrons produced at the same time had exact foacl lengths that > may have been 51.9 but that could have varied with an indivual specimen. > > Unscrew the lenshead from your DR and look for two digits inscribed on the > blackened back part of the barrel. If your lens was really a DR at birth, the > digits must be "19". Leitz dropped the first digit, i.e. 51.9 = 19. > > The digits could be anything from 99 (meaning that with the dropped digit, > that lens would have an exact focal length of 49.9mm) or 23 (meaning that the > focal length is 52.3). I'm not stating limits at either end, simply giving > examples. > > It is entirely possible that you have a Rigid Summicron lens head of a focal > length other than 51.9 and that someone has improperly mated it to a DR > focussing mount. Or it may be the correct 51.9 but the lens head has not been > properly calibrated to the focussing mount. That would not have happened at > the factory. > > Alternatively, if the lens head is 51.9mm, it is possible that the original > focussing mount was damaged and someone found a replacement that has not been > properly adjusted. > > My Rigid 50/2 Summicron happens to be 51.9mm. Last year, I contacted Don > Goldberg of DAG to ask if he might have a DR focussing mount I could use with > the Rigid lens head. He sent me one (since it was a DR focussing mount, it's > automatically 51.9). It turned out that when screwing the lens head in, the > aperture scale was off about 90 degrees to the left of top dead center, > making it awkward to use. Don said he could adjust the lens head to work, but > that meant that when used on the Rigid focussing mount, the aperture scale > would be off 90 degrees in the other direction. I had to send it back. > > Sorry this has been so long but if you're not familiar with the lenses, it > needs careful explanation. Good luck. > > Seth La k9 > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > > - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html