Microscope optics: A: Eyelens; B: Field lens; C: Objective
This objective (No. 4) is the only one remaining with the instrument.
The single, biconvex eyelens (dia=17mm, f=48mm)
Biconvex field lens (dia=29mm, f=65mm)
Objective No. "4" is biconvex (dia=7mm, f=16mm).