Canon Cinema Primes on 5D mk III
I seriously doubt that any of Canon's cinema lenses are optically superior to the standard EOS line up. So far as I know, the main advantages of these lenses for cinema are extremely robust construction (i.e., very heavy), very long focusing turns to allow for smooth transitions in focus point, and very finely calibrated transmission characteristics (T stops instead of f stops) as are required in the cinema industry. If a cinema lens is marked T2.3, that is precisely how much light it will let through and will exactly match any other cinema lens equally marked. This is not true of f stops in consumer lenses. But I believe the most important issue for the cinema people is the highly refined focus characteristics of cinema lenses which allows for smooth and reliable "focus pulling." None of those cinema requirements are very important for still photography.
Also, I believe these lenses are designed to mate perfectly with the elaborate bellows lens shades used in the cinema industry.
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