Archived posting to the Leica Users Group, 2000/04/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Tom Bowen wrote: >My Noctilux had to be returned to Leica USA for replacement because of a bright spot in the middle of the lens due to faulty coating applications. >Then 2 weeks later I order the new 135mm APO f3.4 and the aperture ring sticks and grinds when you try to go between f3.4 & f4.5 And Dominique Pellissier Dominique.Pellissier@droit-eco.univ-nancy2.fr commented: >Leica Camera builds only 10,000 lenses each year. And they say that each lens is "individually checked". What’s important here is that the process of checking is done throughout the production process - that’s what Leica tell people who take the factory tour. Only once a product has passed a series of individual tests at different stages and then a final inspection is it considered good enough to ship. My guide ten days ago at Solms was not a "marketroid" but a former head of the Leica Academy, and his pride in the company’s craftsmanship and quality-control was obvious. So when Tom Bowen gets a 135mm APO f3.4 whose aperture ring sticks and grinds, this is the result of an inspection procedure which has had several near-simultaneous failures. Multi-stage inspection procedures accept that an individual fault may undetected by one fallible human, so arrange that the object is inspected and tested by several different individuals. I read recently that in the Wetzlar era, the documentation for every Leica carried the signature of four inspectors. When this sort of multi-level test and inspection system fails, and a faulty product teaches the end user, something is wrong, particularly in the case of obvious defects such as sticking aperture ring or (to quote a case reported earlier on the LUG) when the bayonet mount on a camera will not accept lenses. Regards, Doug Richardson