Leitz APO 8mm Apochromat 24X/0.65 Microscope Objective Lens

[henryr]

I'm guessing the description means it is a 24x mag objective but what does the 8mm refer to? And is it a 170mm or 160mm?

Thanks,
henryr

[apochronaut]

I owned one of those until a couple of years ago. At one time there was no magnification on objectives. They were just designated by focal length. Anywhere between 40mm and 1.5mm were common. Some companies used inches. Oddly, Zeiss and Koristka around the turn of the century used mm for most of their objectives but inches had become a kind of standard for high power objectives. Oil immersion objectives of between 1/12 and 1/30" were made. A 1/12" objective is about the same as a 1.8mm or 95 to 100X depending on the design.
Microscope companies published charts , which were used to determine magnification in diameters. An 8mm objective used with a 25mm eyepiece would yield such and such a magnification.
Different lens designs would vary slightly from the ideal magnification so a Leitz chart might be slightly different from a Baker chart.
Generally speaking with 160mm tube a 16mm is a 10X, an 8mm is a 20X, a 4mm is a 40X and a 1.8mm is close to 100X.
Leitz, being a 170mm tube would yield slightly higher magnifications for a given focal length. 24X , often marked as 24 : 1 is a little high for an 8mm, even with a 170mm tube. The design is no doubt a bit unique. I recall it being a very nicely performing lens. 37mm parfocal.

Spencer produced a set marked with 16mm 12X , 4mm 62X and 1.8mm 140X. The objectives seem identical to their normal objectives and magnify 10X , 44X and 95X in a 160mm tube. They must have been stamped for a head that had a multiplying telan lens in it.

[henryr]

It is marked A=0,65 24:1 and thought it might be a good addition to my circa 1975 Dialux that I converted to 160mm TL.

[apochronaut]

You would probably need one of those plezy adapters.