Are cheap 100x objectives any good?

[75RR]

Wondering if you might not get a better 'result' with the 40x/0.75 and 15x/16x eyepieces than the 60x/0.85 produced.

Can you simulate the size it would be? Don't suppose you have an Optovar?

[Hobbyst46]

Wondering if you might not get a better 'result' with the 40x/0.75 and 15x/16x eyepieces than the 60x/0.85 produced.
Can you simulate the size it would be? Don't suppose you have an Optovar?

I only have a 10X eyepiece and regretfully, no Optovar.
So I simulated the size - hopefully doing it right: I cropped the 40X to 2/3 the size of the 60X. Thus the 40X is "enlarged" by a factor of 1.5. And resized for upload. So they are not the same resolution pixelwise, yet can be compared.
And, as said before, I believe the 60X would perform better when properly attached to the nosepiece.

[75RR]

Thanks Hobbyst46, had thought the punctae were just about visible in the original 40x/0.75 image - seems not.

[apochronaut]

There are 60x /0.85s, but I think they'd be better off going to 100/ 1.25 oil.

Hi, perhaps the following recent experience with my old, unknown brand (to me) 60X0.85 dry objective (marked only "60X 0.85") will contribute.
It is of 37mm parfocality. I attached it to the nosepiece by means of an RMS-RMS extender ring. Only the first turn of the extender thread is usable, and attaches the objective to the nosepiece. So, the total length of the objective + extender is 52mm and I used coarse focus to raise it above the cover slip. The WD is <~1mm, but, to my astonishement, focusing was not too difficult and the specimen was visible, though not very nice. The compatibility of the 60X0.85 objective with the photo setup is another question.

Here a 50 micrometer long diatom, where stria are separated by 1.1-1.2 micrometer, is observed with my 40X0.75 Neofluar (dry) and 60X0.85 (dry), respectively, in brightfield. The photos are resized and are much cropped. I feel that for secondary school students, a dry 60X would be an acceptable solution for objects measuring a few micrometers.

This looks like it might be a Seibert objective. The optical quality is usually very good.