Microscope Compendium #260, Screw-barrel microscope objectives and base
There are two magnifying lenses for this microscope:
#1: dia=5mm, f=2mm, aperture=<1mm
#2: dia=5mm, f=5mm, aperture = 1mm
The bi-convex lens is held in place between two brass cups. The inside cup is painted black. The assembled cups are fixed in place with a brass retaining ring.

Both lenses have rough edges and are not completely transparent; possibly due to incomplete polishing.

The microscope screws into the top of the instrument base (L) , and over this cone-shaped light guide (R).