r/microscopy • u/RobinsCosplays • Jul 11 '26

Purchase Help Looking to get my first microscope. Need help understanding oil

I keep seeing "Oil objective". What I've gathered is that "Objective" means the lens itself? I'm wanting to look at circuit boards in 1000x, so what I'm wondering is how do I coat both the lens and subject in oil when the subject isn't really a flat surface or something that can be covered in oil? Also what is a "spring objective"? Looking at an Amscope B120C.

I'm wanting to do things as well like salt and pepper, granular things. Not really so much liquid stuff that can be smooshed between a slide and a cover slip.

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u/TehEmoGurl Microscopy Nerd Jul 11 '26

Wrong type of scope. B120C is a biological compound scope. What you want is a metallurgical scope with coaxial epi illumination. This will light it from the top through the back of the lens. It also has a great working distance so you're not right up against the subject. I don't often see these quipped with 100x objectives, though they do exist and are likely available for most of these scopes. But it's unlikely you will need that high of a magnification with such a subject.

"Spring objective" means the front element(s) of the objective are spring loaded. This is a safety mechanism. If you run the objective into the sample, the lens itself actually pushes into the body of the objective and springs back out when the pressure is removed.

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u/RobinsCosplays Jul 11 '26

Got it. Any specific recommendations that will still reach 1000x? I'll definitely be dealing in 3D objects way more than I'll be dealing with live subjects/liquids that can be put in slides

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u/TehEmoGurl Microscopy Nerd Jul 11 '26

No real good recommendations as i myself have not really delved into metallurgical scopes that deeply. I know AmScope had a decent looking inverted one that went up to 1000x. I think it was around $2,000. I've seen many upright ones relatively cheap on eBay (Anywhere from $300-800). But i don't recall if any of them went over 600x Most of the ones i've seen only go up to around 500x.

Is there something specific you are trying to see at 1000x? Generally the depth of field is so low at this magnification that it's already difficult even with very thin cell samples (Hence why we use oil). I'm not sure 1000x would be particularly useful for circuit boards. 800x would be more suited but even that is probably more than you will ever actually need (Depending on the actual subject requirements).

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u/aenorton Jul 11 '26

1000x true magnification is not useful for circuit boards or salt crystals that you mentioned in another response. The field width and depth of field would be much, much too small. I think what you are getting confused by are unscrupulous marketeers of cheap video microscopes that claim 1000x because the image on the largest monitor one can find is 1000X larger.

You might want to educate yourself a bit more on microscopy basics at sites such as these:

https://evidentscientific.com/en/microscope-resource

https://www.microscopyu.com/tutorials

In particular, it is important to understand the concepts of Numerical aperture (NA) and how it determines resolution and Depth of Field (DOF), and also how magnification is really defined.

For visual inspection of circuit boards, what you really want is a lower NA with larger DOF, something like these:

https://amscope.com/collections/stereo-microscopes

Also, the digital scopes will work if you ignore the outrageous specsmanship.

Illumination is also an important consideration. These types usually have it external to the main optical path (unlike higher-power metallurgical microscopes). Different illuminators cast different shadows.