Optics consist of A: Eyepiece with two lenses; B: Field lens; C: Martin "Between Lens"; D: objective. All optics are biconvex.
The objective lenses are mounted on this brass slider. All six lenses have focal lengths <2mm. The lens on the left is the lowest magnification (appx 20x). Imaging is poor however, as the light collection of these small aperture, short focal length lenses is very low.
|
dia
|
f
|
aperture | |
|
A(top)
|
17 | 25 | 13 |
|
A (lower)
|
33 | 55 | 29 |
|
B
|
38 | 55 | 23 |
|
C
|
21 | 105 | NA |
| D | 1–4 | <2 | 1–2 |
Relative position of the four lens systems.