AO microscope parts question

Not metal related, but does anyone know of a forum or newsgroup where microscope enthusiasts hang out? I picked up an American Optical
Model 42 scope at a flea market today and need to buy one ocular for it. I can look through one ocular and see what's under it so it's useable as it. I plan to use it in the shop to look at small parts and the sharpened faces of small cutting tools, plus whatever else a dissecting scope might be useful for.
RWL
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<GeoLane wrote...

I have an English-made binocular scope that I use for exactly that too! Excellent for checking Acme threading tools against gauges, for instance, although I need to make a tiny X-Y-Z stage to go under it!
With luck someone will put you onto a source for the missing ocular, can't help there, but... If you have one ocular, you're half-way there, if it's a simple convex or plano-convex lens (or multiples of - see below) you can measure the focal length of the lens with a very distant light source (the sun, for instance?) by measuring the distance from the lens to its focal plane, that and a few measuements will give you all that you need for ordering a lens (should only be a few local currency units), then the ocular body should be fairly easy to turn up on the lathe? The lens could be held with a threaded ring, or even a circlip in an internal groove.
If it's a more complex eyepiece you may need to dismantle it and do the measurements and then order up a set of lenses to suit, the page at http://en.wikipedia.org/wiki/Eyepiece illustrates the various types - a stereo dissection 'scope will be relatively low-power so is likely to have one of the simpler types.
Dave H.
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    The threaded ring is the traditional design.

    It is more likely to be of the type shown shortly below the "Microscope eyepieces" header in the above-mentioned Wikipedia entry. (Most of what are shown there are astronomical telescope eyepieces.) And in particular, the design of the AO stereozoom microscopes usually calls for "wide field" eyepieces to give reasonable images through the full range -- and that calls for more complex optical design. (As I posted before, I can't find your model with q quick web search. Mine is an AO model 569 (or some number close to that), it is downstairs in the shop (of course), and I did not write down the model number while I was measuring the eyepiece mounting barrel diameter. :-)
    As a result, while you might try making a pair of eyepiece (I would not suggest making a single one, no matter how accurately you measure the lenses and mounting. If you can get the elements needed in pairs, you can at least make matching eyepieces and be more comfortable. With a stereo setup, any mismatch in the two eyepieces will lead to eyestrain. I've already posted a URL for what looks like a good pre-made pair for your purpose.
    If you make your own -- turn very fine threads on the ID of all barrels between and beyond the lenses, and then black anodize (if made from aluminum, or get a very flat black paint to apply to minimize internal reflections. But also -- take care to make the two as close to identical as you can manage.
    Good Luck,         DoN.
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You can see the model in the catalog located at this URL: http://webmight.com/~psneeley/downloads/AO40Catalog.zip
Mine isn't a zoom. I consider it a high school level microscope even though the original list price in the 70s was $500+.
A parts breakdown is available at this site: http://www.xmission.com/~psneeley/Personal/Microscope.htm
After looking at the parts breakdown, I suspect that I need lens assemblies for both oculars. The lenses for this scope are not the usual drop in 10X oculars. There's a stack of lenses in the ocular tube and covered by a black cover that looks much like the exposed part of a regular wide field ocular. Somewhere at work I think I have a pair of 15x oculars that were discarded many years ago. I'll have to bring them home and see if they fit. I could try the oculars from my AO series 10, from my student years, but it's too much work to excavate it from the closet. My suspicion is that these won't work in this scope, but I'll see.
RWL
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On 2010-10-21, GeoLane at PTD dot NET <GeoLane> wrote:

    Hmm ... looking at that, I find this line to be awkward:
        "10X Wide Field built-in"
(from "pg-2.jpg").
    And it looks somewhat newer than my unit.

    So -- you have determined the same thing from direct examination that I have from looking at the catalog you posted.

    Certainly worth a try.
    Best of luck,         DoN.
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On Wed, 20 Oct 2010 02:49:48 +0100, "Dave H."

What is the diameter of the eyepieces?
I may have a pair of something kicking around.
Gunner
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wrote:

The ID of the first half inch of the tube is 0.950" and then it narrows to 0.831
RWL
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On Wed, 20 Oct 2010 22:48:00 -0400, GeoLane at PTD dot NET <GeoLane at PTD dot NET> wrote:

It will take me a few days..Ill check my Stuff. Though Im pretty sure all mine are the same diameter all the way down.
Gunner
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wrote:

...................
............
I brought home a standard 23 mm ocular and tried it. It's workable, but I'd have to make an adapter (not a big deal) or alter the sockets into which the oculars fit.
I may need to make some internal adjustments. With two lenses held in place, the two were neither parcentric (focused on the same area) or parfocal (both in focus at the same time) I couldn't move the lenses enough from side to side to get them parcentric, so I suspect there's some internal adjustment to be made.
RWL
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<GeoLane at PTD dot NET> wrote in message

The double image may be why someone originally removed one of the built in eyepieces . It is likely that one of the prisms inside the swiveling eyepiece tube got knocked out of position.
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On Fri, 22 Oct 2010 12:13:31 -0700, "anorton"

Very possible! I have several Swift inspection microscopes and one of them came that way. Based on close observation of the outside of the body..it got knocked over and the clamps came loose. I played with it for about 15 minutes and got it all realigned nicely.
Ive had several binoculars over the years do the same, but they were all cheapies and I never bothered to try to open one up. I may have a box of them in my Stuff
Gunner
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On 2010-10-20, GeoLane at PTD dot NET <GeoLane> wrote:

    I'm having difficulty finding an illustration of that particular model -- but is it one of the stereo zoom ones with two eyepieces, and a zoom control marked from 0.7X to 3X? With a pair of *matched* 10X eyepieces, this gives you a very comfortable range for the sort of thing you want to do. The "matched" means that you cannot trust getting a single eyepiece that it will match what you have closely enough.
    You want 10X wide field eyepieces for this.
    Doing an eBay search for "stereo microscope eyepieces" I find several which look reasonable. Here is an example:
    eBay auction # 310262853424
    mine measure 23.23mm small end diameter which is pretty close to these.
    No idea about the dealer.
    Many shorter eyepieces probably are not wide field enough, and are also probably not the right length to focus properly in the stereo zoom microscope.
    I would suggest that you measure the smaller end of the eyepiece which you have to check what size you need for your 'scope.
    If you go through the search -- you will find rubber caps which fit on the eyepieces and block off side light, as well as spacing your eyes to a comfortable distance -- assuming you do not use glasses. If you do wear glasses for infinity focus, use the bare eyepieces without the caps added.
    Good Luck,         Don.
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Good advice. I would add that I am fairly certain the AO microscopes used a 23.2 mm diameter eyepiece (note: sometimes there is a number after the the magnification written on the eyepiece. This is NOT the diameter. It is called the field number which is the diameter in mm of a field stop inside the eyepiece. Divide it by the objective magnification to get the field width at the sample.)
If you search Ebay for just "10X eyepiece" you will get more hits. If you do not see an eyepiece that seems to exactly match your make and model, you really should get 2 new matched ones so you do not have slightly different magnifications in each eye. As noted by Don above, you want wide field for a low power stereo microscope. Also, some eyepieces are easier to use with glasses due to the longer eye relief. Sometimes these will have a little glasses symbol on the side. Otherwise you can generally tell since longer eye relief eyepieces have a larger lens in front.
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wrote:

I calculate that to be 0.915". My ID is 0.950" so technically those objectives could be made to fit. Whether they're the correct ocular length for that tube might be another story.
RWL
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you could try emailing me off the net, I have a couple of spare eyepieces - maybe what you need
get my email from my web site, wbnoble.com
<GeoLane at PTD dot NET> wrote in message

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On Oct 19, 8:51pm, GeoLane at PTD dot NET <GeoLane at PTD dot NET> wrote:

These guys will be able to help you figure out what you need, and will give you a square deal: http://www.microscopejsic.com /
I can not reccommend John Simon highly enough. I've bought two microscopes from him - he gave me an unconditional money-back guarantee, and took the first, five years later, at full price as a trade-in on the second. A real class act.
BTW, if you're ever in the area, his antique microscope collection is worth a look.
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On Wed, 20 Oct 2010 04:45:52 -0700 (PDT), rangerssuck

I sent an email inquiry.
RWL
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GeoLane at PTD dot NET <GeoLane at PTD dot NET> wrote:

I follow the "sci.optics" newsgroup, and someone on that list will likely know where to look. There may also be a group for microscopes - search the groups for "microscope".
Joe Gwinn
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On Wed, 20 Oct 2010 08:59:32 -0400, Joseph Gwinn

Thanks Joe. That's a potential lead.
RWL
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<GeoLane at PTD dot NET> wrote in message

GL:
sci.techniques.microscopy has some informed posters. If you are filtering posts from googlegroups and yahoo.cn, it is much, much easier to read. That said, eBay is a good resource.
Regards,
Edward Hennessey
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