You have a number of prime 16-mm. film lenses that are very similar in design, the six-element double-Gauss systems, Zeiss Planar derivatives. Among the one inch or 25 mm focal length lenses there are the TTH, Schneider Ciné-Xenon, Angénieux S41 (IIRC), Rodenstock Heligon, Leitz Summar, Berthiot Cinor, Kern Switar, and more. Older Kern have brass and or bronze mountings while Schneider, Angénieux, Berthiot, Dallmeyer, and Leitz employed aluminum, anodized aluminum in later years. Kern also changed to aluminum in the 60s. I think it is the heavy metal make that has become so attractive.
The Switar 25-1.4 is not fully corrected. The Switar 26-1.1 RX is an apochromatic lens and therefore more expensive. But one pays a price for the wide opening. The Kinoptik 25-2.0 Apo lens doesnt’ have the same softness.
I’m in this subject since years and always come to the conclusion that the main technical problem with motion-picture machinery is film flatness. To be precise, non-flatness. The film has room to move and it can behave in a complicated manner in the various cameras. When I measure a piece of polyester-base 16-mm. film I regularly find 15,95 mm as prescribed by the standard (ISO 69). Triacetate-base film can be shrunk down to 15,92 mm width and many a camera won’t guide a strip that narrow. The complicated film run may still prevent the film from swaying about but flatness within, say, two hundredths of a millimeter or a mil is no longer secure. Eclair, Aaton, Arnold & Richter, Photosonics, Paillard, Mitchell, Bell & Howell, Fairchild, they also just put their pants on one leg at a time. Any discussion of lenses is void if a camera is malfunctioning. I have found Bolex with too long FFD (wrong shim), with an aperture plate that has a raw front surface, with too wide an aperture plate which prevents the blade springs reaching the film edges, and more such stuff.
Here we read 16,020 mm. The upper limit of film width is 15,975 mm. Funny, isn’t it?