Archived posting to the Leica Users Group, 2005/06/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I don't know Gene. When an element is de-centered or has a spacing problem, we are talking about an error that is measured in a 1/10th or 1/100th of an inch. Not exactly something you can see with the naked eye. Back at my old job we had a machine shop where we would build custom camera and lens setups and you would be surprised to see, just how far off something can be, that looks perfectly 'ok' to the naked eye. But if it works for you, fine. Personally I would send it to an expert with the right tools and training. feli On Jun 27, 2005, at 1:40 PM, Gene E. McCluney wrote: > In all the Leica lenses that I have disassembled, the elements fit > into machined depressions in the > lens mount. Each element fits precisely. I see no way an element > can be de-centered, as they > fit exactly and precisely with no play. In other words, it appears > that the "centering" is done > during the fabrication and initial assembly, and subsequent > dismantling and re-assembly shouldn't > affect the overall "centering" that is built into the lens. > Disassembly ad reassembly using the same lens elements should > result in exactly the same "factory" centering. > > The case for a lens needing "re-centering" using a collomator is > highly exaggerated, in my opinion , > at least when it comes to Leica lenses. Just make notes of what > goes where when taking apart. Some Leica lenses have thin fibre > washers to separate elements. These should be put back exactly as > originally installed. But even with this, the glass elements fit > into milled depressions in the lens mount structure, and cannot > decenter laterally. If the glass is "seated" when assembling then > no de-centering will occur. > > The above is in reference to the "optical block" of a leica lens > and does not address the helical focusing mount, which is of course > possible to re-assemble incorrectly. It is possible to > disassemble the optical elements of most lenses without disturbing > the helical focusing mount alignment. There are a number of Leica > lenses where the "optical block" completely unscrews from the > helical focusing mount, leaving the focusing mount undisturbed. > > Gene McCluney ________________________________________________________ feli2@earthlink.net 2 + 2 = 4 www.elanphotos.com no archive