lct Posted February 22, 2010 Share #41 Posted February 22, 2010 Advertisement (gone after registration) So it's mainly a lens issue. Thanks Jeff and Jamie. Link to post Share on other sites More sharing options...
Advertisement Posted February 22, 2010 Posted February 22, 2010 Hi lct, Take a look here Red Edge - Red Middle?. I'm sure you'll find what you were looking for!
ho_co Posted February 23, 2010 Share #42 Posted February 23, 2010 ... Also, his lens the 50lux I believe corrects CAs using special apo glass (not sure about that tho).... You're right to say you're not sure. Such a thing as "special apo glass" doesn't exist. And the 50 Summilux isn't an apochromatic design. It's a common misperception that APO lenses will not show chromatic aberration. The term "apochromatic" when used with lenses doesn't have a truly official status, but is generally used to indicate that all the spectrum is brought into focus at the same point. An apochromatic lens can still show LoCA, because the CA you are seeing is actually on either side of the plane of focus.... Jeff, you're correct that "apochromatic" as used in today's marketing speak hasn't a formal definition. Technically, it isn't possible to bring the full spectrum into a single focus. It suffices to bring three widely-spaced colors to the same focal point; to completely correct for spherical aberration at two widely-spaced colors; and to completely correct for coma at one. Check Defining Apochromatism for a clear explanation from the year 2003. Of course, other lens designers' definitions will be more or less exact than Back's, since as you say, the modern definition has become quite flexible. Link to post Share on other sites More sharing options...
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