Achromatical, 20:1, RMS, incident

Achromatical incident light objectives for tube length 160 (RMS thread, parfocalizing length = 45 mm) 

Magnification: 20:1
Focal length: 7.84
Numerical aperture: 0.40
Working distance (mm): 1.8
Theoretical sharpness depth (mm): 0.002
Parfocalizing length: 45