Made of glass with polished face and ground edges. Refractive
index 1.52 approximately.
| Diameter 38mm Focus mm | |
| -01 | 50 |
| -02 | 75 |
| -03 | 100 |
| -04 | 150 |
| -05 | 200 |
| -06 | 250 |
| -07 | 300 |
| -08 | 500 |
| -09 | 1000 |
| ? | ? |
| ? | ? |
| Diameter 50mm Focus mm | |
| -11 | 50 |
| -12 | 75 |
| -13 | 100 |
| -14 | 150 |
| -15 | 200 |
| -16 | 250 |
| -17 | 300 |
| -18 | 500 |
| -19 | 1000 |
