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Any microscope experts here?

Hi folks,

I'm thinking about buying a microscope. I have several old microscopes in various states of disrepair, which I got for nothing. But I've wanted a reflected light microscope for a while. I've seen a Watson "Standard Metallurgical" reflected light microscope for sale pretty cheap. I already have a bunch of Watson spares, so it looks like a tempting buy.

However, I don't know much about microscopes, and various issues are confusing me. So I'm hoping people here might be able to help.

  • I have lots of Watson lenses with an RMS thread. These came from a school and were used on transmitted light microscopes. As far as I know, the lenses I've got and the microscope I've seen for sale both use lenses designed for a fixed tube length, not infinity-corrected lenses. So can I use my spare Watson lenses on a reflected light microscope, or do I need special lenses designed for use with reflected light?

  • Presumably there's no way of using infinity-corrected lenses with a microscope intended to have a fixed tube length? I've read that the infinity-corrected microscopes have an extra lens in the tube somewhere.

  • The microscope I'm thinking of buying doesn't have a nosepiece which carries multiple lenses. However, I have several spare Watson nosepieces, and shorter drawtubes to accompany them. I tried them out this afternoon. Now my understanding is that when you use the nosepiece, you should be able to fcous using a low power objective lens, then switch to a high power objective and find that everything is still in focus. It doesn't seem to work, even with lenses from the same manufacturer. I always have to correct the focusing after switching lenses. Is my understanding wrong, or does the microscope I'm using need adjusting somehow?

  • I want a low power combination of lenses. Watson don't seem to have manufactured an objective below x2.5 and an eyepiece below x5. I'd like to go lower than this. Olympus manufactured a x1.3, but it's intended for a microscope with a 200 mm tube length. The Watson microscopes can be extended to 200 mm tube length, but it clearly isn't their normal setting. What would happen if I tried to use an Olympus lens with a shorter tube length? Would I just get a different magnification and focusing distance, or would everything get royally screwed up? I think the Watson microscopes have a default tube length of 160 mm, but it appears to be adjustable from 155 to 220 mm with the nosepiece fitted.

Does anyone have any advice or thoughts? Is this a good idea? Suggestions would be appreciated.

Best wishes,

Chris

Reply to
Christopher Tidy
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Not an expert, but have spent many hours hunched over them peering at microstructures, trying to make sense of what I see. ("Is that Martensite, or just lots of scratches?")

I can't intelligently comment on your specific queries re the Watson gear, but am happy to relate some experiences.

I've always used, with mixed, (but usually reasonable) success, a variety of inexpensive reflected light microscopes and would like to share some nice features.

  • light source must be variable, preferably continuously, else it will always be too bright or too dark.
  • focus mechanism tightness must be adjustable (or tight enough) to avoid creep under gravity. I had one 'scope which would allow the objective lens to gradually settle down onto the specimen (!). I forget if it was an easy adjust.
  • facility to accept polarising filters. Can help.
  • I've only ever used mono 'scopes, but binocular would be nice - trinocular even nicer if you are planning photography. Mono will do, 'though. ($$$)
  • a nice micrometer-adjustable (smooth and backlash-free) X/Y platform on the stage makes viewing much more comfortable. (Do all 'scopes have this nowadays?)

If buying secondhand, look for all the obvious things (smoothness of focus etc) and don't forget to look for fungus in the optics.

Most of the ones I've used have been no-named beasts made (I think) in Czechoslovakia, mingled with a few Olympus (nice) ones. None of them were hideously expensive, and a good one will last forever, treated properly. Lash out and spend more than you want to. You won't regret it, and neither will your heirs.

-- Jeff R.

Reply to
Jeff R.

FWIW, I sold the body of such a transmitted light microscope on ebay last year - it went for ten or twenty dollars, and I shipped it internationally - shippng was more than the auction price - so if you have lenses, you should look and see if someone else finds a body without lenses

Reply to
William Noble

[snip]

I won't get into addressing your specifics, as I only have 2 reflected light microscopes (one is a polarising scope used for petrographic work, the other for looking at surface defects via Nomarski DIC). However, your best bet is to post your questions on sci.techniques.microscopy. There are several knowledgeable folks who will help. Some will assume you have an unlimited budget, though! Several are hobbyists, so are aware of the constraints of the purse.

The short answer about the infinity-corrected objectives is that they will not work with a fixed-length stand, because, as you noted, there is an intermediate lens required in the infinity system.

Check out:

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*lots* of excellent tutorials, and:
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for other good stuff microscopically.

Welcome to another fun world of adventure and (most importantly) toys, er, uh, tools.

Joe

Reply to
Joe

Indeed. There seem to be a lot of exceptional instruments going at very low prices at the moment.

Best wishes,

Chris

Reply to
Christopher Tidy

Thanks very much for all that useful advice, Jeff.

I'm on a budget, but as a philosophy I definitely believe in investing in good equipment and tools. You get what you pay for.

Best wishes,

Chris

Reply to
Christopher Tidy

Thanks for clarifying that, Joe.

:-)

Best wishes,

Chris

Reply to
Christopher Tidy

What are you going to do with this microscope? I use a couple stereo zoom microscopes (Bausch & Lomb and Olympus) for all manner of work. But, then I am examining 3-D objects, not surfaces, as in metallurgical work. I use it mostly for micro-soldering and examination of soldered SMT parts, but also for other things.

Jon

Reply to
Jon Elson

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