Optics of the Adams Variable compound microscope: A: Objective; B: Martin "Between Lens"; C: Field; D: Eyelens. All optics are biconvex, simple lenses.
Diagram of the position of the lenses of the Adam Variable microscope. Distances between lenses are as follows:
A-B: 10cm
B-C: 10cm
C-D: 4.5cm
Vertical lines indicate the extent of the two drawtubes.
| Dia | f | |
| Eyelens | 16mm | 30 |
| Field | 28 | 70 |
| Between | 19 | 110 |