Achromatical, 2:1, RMS, incident

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

Magnification: 2:1
Focal length: 75.59
Numerical aperture: 0.05
Working distance (mm): 18
Theoretical sharpness depth (mm): 0.043
Parfocalizing length: 45