This 16mm reflex has bright viewfinder.  However, when tested the focusing is slightly inaccurate:  about 1.5 inches out at 73 ins. (With most filming the depth-of-field may take care of this.)  Accepts  c-mount lenses.  Takes 100ft spools and has door for 200ft mag.  Speeds: 2-64 fps.  Needs battery.  (You could wire up a pack of 5x AA batteries !)