Purpose of specific condenser part?

[J_WISC]

Hello.

Can someone describe the purpose of the knurled threaded ring here?

It appears redundant to thread the lens into the holder, then attached the knurled ring inside the holder. It is actually a bit difficult.

Does the lens get threaded into the ring, then into the larger holder? Is it for adjusting the height of the lens, that is, how far the lens goes into the holder?

unnamed-1.jpg (141.46 KiB) Viewed 1552 times

Thank you.

[MichaelG.]

I would assume that the lens screws into [and protrudes through] the large holder, and then the small ring is used as a lock-nut.

Do you know what microscope it fits ?

MichaelG.

[Chas]

My guess is that it is primarily to lock the condenser into place (imagine an objective not fully tightened up) it might also serve to inhibit immersion oil dribbling onto an iris underneath.
Spencer? :

Spencer condensers.jpg (131.38 KiB) Viewed 1503 times

[zzffnn]

I am guessing that design allows condenser top lens to be adjustable and stay tight at specific heights (when the lock ring is not used, the other two parts may be loose and wiggle at highest height).

[apochronaut]

The reason that lock ringnut is on that condenser only is because it has an R.M.S. thread and it is needed to lock the height for the 1.3 achromat condenser or any objective or DF condenser threaded into the iris section. There would be a broad range of heights from about 20mm to just under 37mm, later upping to 45mm, with each condenser choice also potentially extendable on it's thread somewhat if necessary.

The mated condenser dovetail mount itself or iris diaphragm section was used almost exclusively on Spencer's research microscope models so there was an expectation that matching objectives would sometimes be preferred by the research community as an optical pairing. The principal is somewhat similar to vertically illuminated microscopy where the objective does not have an annular illumination ring.

The lock nut more properly belongs to the iris section but since there is no way to keep it there, it resides on the condenser.

[J_WISC]

EDIT:

I apologize. It is the condenser on the Spencer #5.

(I don't feel well this week and not getting enough sleep.)

Thank you for correcting the error.

[apochronaut]

That's the condenser for the # 15 or is it 16? That looks like the condenser for the # 5.