Bristol microscope objective, 40X/0.65, 0.17mm cover glass, W.D. 0.60mm, works

Description

Item for sale consists of a Bristol microscope objective lens with a long working distance. While this lens does not have a country of origin engraved on it anywhere, it is nevertheless it is assumed to be Japan, where the Bristol brand of microscopes originated. It is an A 40X lens (achromatic) with a 0.65 numerical aperture. It is designed for a 0.17mm cover glass thickness and a W. D. (Working Distance) of 0.60mm. The parfocal distance was measured to be about 37mm, and a tube length of 160mm worked very satisfactorily in the practical tests on an actual microscope. The lens is in good condition optically with exposed glass surfaces that show no sign obvious signs of scratches, fungi, or other problems. In the tests, it was found to produce correspondingly good images. Cosmetically it is likewise in good condition with an attractive bright metallic finish, though there has been some loss of plating around the tip (bottom) of the lens. Please examine the photographs carefully for further details about the cosmetic condition.