Lens parameters:
Lens structure: 6 6 groups，
Appearance size: 108mmx77mm
Diagonal: 43.27，
Focal length: 500mm
Image plane: 36x24，
Magnification: 2.1 times
The closest distance: 1.72m，
Filter diameter: 72mm
Aperture: F8，
Threaded connection: M42X0.75