Questions about Leitz Ultropak oil immersion procedures

[bill2penn]

Greetings,

I have some questions about Leitz Ultropak oil immersion. According to Leitz literature (attached, pages 13-16) a coverglass is cemented onto the oil cap of the Ultropak objective and it is arranged to be close to the objective. Immersion oil is added between the objective and the cover, and then oil is used between the cover and the sample. I don't know what the reason is for this design. It's oil immersion but with a coverglass in between the objective and samples. Does anyone know the reason for this design?

If you didn't have the oil cap, do you think that using oil immersion like a regular objective would work? Or is there something about the illumination that will cause issues.

Thank you for any help.
Best,
Bill

[Aljoscha]

Hi Bill,

Those immersion caps convert a dry objective into an immersion objective. Yes, the immersions media (water glycerin or oil) needs to be between the objective and the cap and between the cap and the object. Immersion without the cap would not work.

The reason for this design is reduction of stray light. It greatly improves contrast and brilliance.

Regards

Alexander

[bill2penn]

Hi Alexander,
Thanks for your answer.
I am inquiring since I just purchased a set of Ultropak objectives, including 3 immersion objectives: UO 23X (oil and water), UO 60X(oil) and UO 100X(oil). I will test them using just immersion without the cap (since they don't have the EZ 23-100 caps) after I receive them and see how they perform.
I will report my findings afterwards.
Best regards,
Bill

[Aljoscha]

Hi Bill,

Those caps are dark-field condensers, which is the typical use of Ultropak. Use the one you have: 22-100.

Immersion caps are a total different thing.

Regards

Alexander

[bill2penn]

Hello Alexander and all,

I recently purchased a partial set of Ultropak objectives in a fine wooden case. Several of the objectives are unusual (to me anyway) immersion objectives probably from the early days of Ultropak. I was wondering if anyone had any information on these in particular: 11X 0.25 Oel and W, 23X 0.55 Oel, 60X 0.85 Oel, and 100X 1.0 Oel. In the literature I have access to, I can find no mention of the 11X oil and water immersion Ultropak, and the 23X in the literature I have access to is listed as both oil and water, not just oel as it is here. Also my literature lists that the 60X and 100X are fluorite but there is nothing here or engraved on the objective that says that. I have attached some images. All are in great shape, save for the condenser of the 11X Oel and W which is cracked. The 22X was missing but I already owned one. I plan to check them out later this week.
Regards,
Bill

[bill2penn]

I did some test images with one of my diatom slides using the 4 Ultropak oil immersion objectives. These are the 11X, 23X, 60X, and 100X as single focus images. The images were cleaned up in the usual way. I think I like these Ultropak objectives!
Bill