Ask you about the focal length of C-port camera lens.

This is a zoom lens with a focal length from 10mm to 100mm and a constant maximum aperture of 1.6. This lens is the photographic lens of 16mm film machine. GDB- 10X 10 means that the shortest focal length is 10mm and the zoom is 10 times.

The flange distance of this lens, that is, the distance from the mounting flange on the back of the lens to the imaging surface, is17.5 mm.

Known focal length f= 10~ 100mm zoom, image distance and object distance can be determined by the following formula:

1/ focal length = 1/ object distance+1/ image distance