MicrobeHunter.com Microscopy Forum

Noob question here. What is this ring for? I have everything I need to start observing except the microscope!! So as I stare at blank slides and peer into my sample jars questions pop into my head . I think it’s to make it parfocal with the other objectives, but I don’t know.

If it turns, there are two likely possibilities.

One is an iris inside to adjust contrast. Useful for darkfield. If you look through the lens you'll see an aperture opening and closing.

The other is to adjust lens elements to adjust for cover slip thickness. If so, you'll likely see graduations along the side ranging from maybe .11 to .20 mm or so. It's to tweak the optics to get a decent image on a dry objective at 60x. FWIW, for the trouble of adjusting these just right, one might often prefer to use oil immersion and get even higher resolution.

A picture would help but it is most likely one of two things. 1) a correcting collar which moves internal lens elements to correct for spherical aberration caused by using a coverslip other than one of ideal thickness. 2) an iris diaphragm control that is used to reduce the N.A. of the objective, which is useful for effecting certain contrast techniques. Dark Field and fluorescence mainly.


There are also objectives that have a loose ring or collar that rotates only to present the magnification to the exterior so you can tell one from another. pre colour coding.

If it's just a regular objective with no controllable iris, then the knurled ring has only two purposes.

1. To make it easier to screw in and unscrew.
2. To make it look cooler looking than an objective with no knurled ring.

If I read correctly on previous threads, you bought an Amscope?

If so, than that's the purpose of the knurled ring on your objective.

I also have the knurled ring 60x plan objective. it's rad, righteous and awesome.

If it is an Amscope objective, it will have a wide spaced knurled ring so that when you look at all the objectives in the storage box it is identified as a plan objective. Other objectives will not have that type of knurled ring.
Greg

Greg Howald wrote: ↑

Tue Apr 20, 2021 10:47 pm

If it is an Amscope objective, it will have a wide spaced knurled ring so that when you look at all the objectives in the storage box it is identified as a plan objective. Other objectives will not have that type of knurled ring.
Greg

That's interesting. I never noticed that before. Good eye, dude.

Thanks to all for the input. The ring does nothing as I turn it , looking down the objective, and there are no markings near the ring. I think it’s Greg’s answer that nails it. It is the Amscope plan objective, and it’s good to hear that it’s awesome RedGreen! Now if only had my scope!! Thanks again all, J.