pgk Posted May 31, 2011 Share #1 Posted May 31, 2011 Advertisement (gone after registration) For a 'custom project' I needed a Canon male bayonet mount and my local photo shop kindly gave me a Sigma lens which had stopped working and was completely dead. Removing the bayonet proved easy enough and revealed severe internal rusting - obviously the lens had had a soaking and this was the cause of its demise. Having removed the mount and being curious, I decided to strip the entire lens down just to see how it was put together. With hindsight I should have photographed this because it was fascinating. I was amazed at how much of the construction was plastic including some sections which held the lenses both in place and in their relationship to each other. The whole mechanism appeared to me to be built around its production requirements and I cannot see how such lenses can be economically repaired, as stripping them is a messy business and I would hate to have to attempt reassembly. My overall impression was of a very high technology product which made much use of modern precision plastics with few metal parts in evidence. My point in posting here? Well it made me realise just how 'traditionally' built my Leica M lenses actually are, and to what degree of precision they are built given their size and mechanical complexity. The Sigma used a complicated plastic precision molding with various cams which seemed to control the zoom by shifting various optical cells around, but as far as I could tell it must rely purely on manufacturing tolerance to ensure that everything aligns properly and that the optics produce good images. I could not see any way of making any adjustments to realign anything (although obviously I am no expert). The latest M lenses with their focus and shifting elements together with Leica's ability to strip and realign and adjust them really are quite amazingly made and are obviously built with an entirely different intent. Link to post Share on other sites More sharing options...
Advertisement Posted May 31, 2011 Posted May 31, 2011 Hi pgk, Take a look here Lens build quality. I'm sure you'll find what you were looking for!
mmradman Posted May 31, 2011 Share #2 Posted May 31, 2011 Your description brings memories of expensive repair on Nikon 24-70mm AFS lens following minor knock some two years ago, almost 50% of the cost of the new lens, fortunately it was covered by household insurance. Ever since then I have been migrating towards manual focus lens and Leica gear of course. Link to post Share on other sites More sharing options...
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