Made from optically worked glass, ground edges.
Focal Length (cm)
Dia mm (1) (2) (3) (4) (5) (6) (7) (8)
A 38 5 10 15 20 25 30 50 100
B 50 5 10 15 20 25 30 50 100
C 75 5 10 15 20 25 30 50 100
