t024484 Posted June 9, 2009 Share #1 Posted June 9, 2009 Advertisement (gone after registration) In an article written by MJH dealing with Hasselblad lenses, I noticed that there can be a big difference in MTF for a the lens when set to infinity, or at a nearby distance. At what distance setting did Leica measure the MTF diagrams that are publishised on their website? Hans Link to post Share on other sites More sharing options...
Advertisement Posted June 9, 2009 Posted June 9, 2009 Hi t024484, Take a look here At what distance setting are Leica MTF´s. I'm sure you'll find what you were looking for!
lars_bergquist Posted June 9, 2009 Share #2 Posted June 9, 2009 Photographic lenses are normally optimized at infinity. Dedicated macro and copy lenses may be optimized for closer distances. Definition does normally fall off considerably at close focusing distances, especially with fast lenses. The old collapsible 5cm Summicron was quite soft inside 2 meters. The original 50mm 2.8 Elmar however was designed to work equally well at all distances. With modern lenses the problem is often combated with floating elements. I think Olympus were first to produce a 50mm Macro with floating elements -- it was and is still a great lens. The old man from the Age of Close-Up Lenses Link to post Share on other sites More sharing options...
jaapv Posted June 9, 2009 Share #3 Posted June 9, 2009 Normally MTF curves are calculated at infinity, unless specifically stated. Leica's MTF values are not measured, but calculated. Link to post Share on other sites More sharing options...
A Sfeir Posted June 9, 2009 Share #4 Posted June 9, 2009 Normally MTF curves are calculated at infinity, unless specifically stated. Leica's MTF values are not measured, but calculated. Is this the case? then precision of manufacturing / assembly / tolerances are not accounted for in the MTF? Link to post Share on other sites More sharing options...
Marty Posted June 9, 2009 Share #5 Posted June 9, 2009 Is this the case? then precision of manufacturing / assembly / tolerances are not accounted for in the MTF? In the case of Leica these tolerances are usually such that measured = calculated, or at least that is the idea. Link to post Share on other sites More sharing options...
lars_bergquist Posted June 9, 2009 Share #6 Posted June 9, 2009 They do measure the MTF of sampled specimens too--in order to check that Manufacturing is on its toes. The old man from the Age of the Tacked-Up Newspaper Link to post Share on other sites More sharing options...
jaapv Posted June 9, 2009 Share #7 Posted June 9, 2009 Advertisement (gone after registration) That is true, Lars, Laser interference measurement and the whole lot too. I was referring to the publicized MTF graphs. Link to post Share on other sites More sharing options...
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