Optics of the Smith & Beck microscope. Eyecups (A), top eyelens mount (B), Huygenian eyepiece consisting of Eyelens (C) and Field lens (D); drawtube (E), body tube (F), objective (G). The drawtube has markings spaced 2.5cm apart.
Huygenian eyepiece consisting of two plano-convex lenses separated by 6cm. The top, or Eye lens dia=12mm, f=19mm. The bottom, or Field lens dia=17mm, f=38mm.
There are two existing objectives with the microscope. One low magnification objective (1 1/2), and one high magnification objective (1/5). The latter has engraved "Uncovered" and is fitted with a correction collar. Probably this objective was designed to be used with no coverslip.
"Uncovered" lens with correction collar.