Pinterest sent me a link to an amazing collection of vintage camera images... I have used some of these cameras but, have never touched nor even seen in person many more...
Such as this three lens turret Leica...
I have saved this link as a reference. Clicking on each image brings up several additional images along the same theme...
https://www.pinterest.com/spyrostsic...078&utm_term=2
This Bell and Howell, Model 70 DR was my favorite silent 16mm motion picture camera for hand-held work. My three lens combination on this camera was usually a 10mm Angenieux lens along with 15mm and 25mm lenses.
I liked to use three lenses which ranged in focal length from very wide to normal angle because I could hand hold them with better results than if I used a longer lens.
The Filmo was a spring operated camera which accepted 100 foot loads of 16mm film. Our standard emulsion during the late 1960's to early 1970's was Kodak 16mm Commercial Ektachrome which had an ASA (comparable to ISO) of 25 under tungsten lighting or 16 with the addition of a Wratten 85 filter (this gave use a normal exposure of f/8 to /11 in bright sun). I cut the gel filters into circles and placed then behind the lens, retained by a small circular spring, before the lens was mounted on the turret. When you rotated the lens turret, the objective turret was geared to rotate along with the lens. A problem could happen if the lens turret or objective turret got twisted accidently and independently. That way you could be viewing the scene looking through an objective showing the field of view for the wrong lens. That was very embarrassing when the footage was viewed after processing. Needless to say, that usually happened only once. After it happened, the cameraman was usually quite careful about having the lens and objective lined up properly.
BTW: this little (in comparison to other mopix cameras of the era) was virtually indestructible and the cameraman did not need to worry about having a set of charged batteries,