Up for sale is a lot of vintage American Optical microscope condenser parts from a university lab. It comes in its original storage box, which has a typed label reading "Iris Diaphragms, AO" and "Condensers," with "Darkfield" written in by hand.

The main pieces are four darkfield condensers, each installed in an aluminum centering mount with two knurled centering screws. Each condenser is engraved "1.15 TO 1.25 SL.TH.," which gives the slide thickness it is designed for. AO used this marking on its oil-immersion darkfield condensers, and the dark central stop is visible in each top lens. A few of the aluminum rings have old inventory numbers scratched in.

The lot also includes:

• five black AO substage iris diaphragms with operating levers

• an American Optical Co. centering condenser mount with iris, marked "Buffalo, N.Y., Made in U.S.A." and hand-numbered 1548R9b. It has two centering screws and a threaded top socket, and comes in its own vintage air mail shipping box labeled "Prince – 1548R9 Scope, Apo Objectives 2, Condenser – 1548R9b."

• a gray condenser with a brass ring, a large top lens, and a swing lever, maker not identified

• three small threaded cone-shaped pieces that look like darkfield funnel stops, which are inserted into the back of an objective to reduce its aperture

• two lens cells still sealed in their plastic bags, which look unused

Everything is used and vintage. The chrome condenser caps show light scuffs and some residue, and the glass should be cleaned before use. The black finishes show handling marks. Nothing has been tested on a microscope, and I can't confirm which stands these fit, so the lot is sold as-is. Please see the photos for the full condition, as they are part of the description.

This is a great lot for anyone restoring a vintage AO or Spencer microscope, setting up darkfield, or stocking parts for repair.