The astronomical eyepiece is a Huygens - Campani eyepiece consisting of two planoconvex lenses placed at a distance of 3.5 cm one from the other, with the flat side facing the observer. The one closer to the observer has a focal length of 40 mm and a diameter of 10 mm; the other has a focal length of 30 mm and a diameter of 15 mm; it is 10 cm from the erecting system.
Of a faraway object the objective gives a real and upside-down image which falls in front of the first focus of the erecting lens; the latter gives a real image that falls beyond its second focus and, being upside-down with respect to the image given by the objective, it is right side up with respect to the object viewed.
The observer adjusts the position of the astronomical eyepiece in such a way that the final image forms at the distance to which the eye is adjusted.
A diaphragm with a 14 mm hole is placed at a distance of about 6 cm from the objective and another with a hole of 7.4 mm at a distance of about 2 cm from the pupil.
The eyepiece is equipped with a rotating cap.
A longitudinal strip of the veneer is missing from the first tube. Otherwise, the telescope is in fairly good condition.