More elements, more air glass surfaces.
More surfaces, less transmission, more reflectance.
This is 'flare', and it creates the the softer blacks you see.
It is like adding 1 or 2 exposure units to the film: the effect is more noticeable in the dark areas, hardly noticeable in the midtones. Classic cine lenses, like a pre WW2 Speed Panchro (similar in design to most current 35 mm fast lenses) made very soft shadows because of the flare. After the war, when coating was no longer a military secret, lenses with several air glass surfaces became a viable product. Zoom lenses have many more air-glass surfaces, and until multi layer coating were always soft in their tonality.
Today's objectives are very close to perfect, which is why 'cult lenses' are still coveted by some. On the other hand, you can shoot things with a Zeiss prime that defies imagination in a 1940 cine context/
Lens terms: this is a good resource for Nikon lore,
http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/
Like all things, if you have access to a rental house, or a prop camera shop, you'll be able to test this stuff and see for yourself.
Sounds like fun.
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