Which eyepiece?

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Jay Ray
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Joined: Sun Jul 08, 2007 4:40 am

Which eyepiece?

Post by Jay Ray »

Hello everyone,

I've got an old series four AO 'scope. The infinity lenses that came with it were just replaced with sine Nikon 160mm; thank you, Ebay. Next step, to acquire new eyepieces. But I'm a bit puzzled. Gordon Couger from microscopehobby yahoogroups said the eyepiece should "match", but I little more than a guess as to what that means.

So what makes an eyepiece "match"?
Do they also have to be built for 160mm tube length?
Or is there some quality in the lenses that counts? For example, the objectives are "E Planochromat". Should the eyepieces also be E Plan?

Anxiously waiting to peer,
Jay Ray
Me < Science

Epidic
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Joined: Fri Aug 04, 2006 10:06 pm
Location: Maine

Post by Epidic »

Matching means the eyepieces were factored into the scope design (but there are no specific EPs like plan or APO to match an objective). They will correct for the limitations of the optics. I am not sure how careful you really need to be about that. What I would suggest is simply getting Nikon EPs (10x) for your Nikon objectives, preferably from the same period so you get EPs designed for a scope with a certain tube length / optics, but there again I don't think that is such a big deal.
Will

Charles Krebs
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Post by Charles Krebs »

Jay Ray,

You've got me a little confused. Do you know if the AO Series 4 was designed to use "infinity" optics, or was it a a "finite" 160mm tube length microscope.? If the latter is the case then it should not have had "infinity" objectives on it. But... if that is so, then it should work OK with the 160mm tube length Nikon objectives. (The reason you need to be sure is that if the microscope was made to use infinity optics then there will be a "tube lens" in the viewing head, and if so, you may have image quality problems using finite objectives). With used microscopes it is not unusual to find all sorts of mismatched arrangements-- "infinity" objectives in a "finite" scope where there is no tube lens in the microscope... usually a bad idea! Or... finite objectives in a microscope that was made to use "infinity" objectives and therefore has a built in tube lens... also not a good idea.

As to the eyepieces. In most microscopes using finite optics there was some additional optical correction that needed to be made by the eyepieces. The notable exception was the Nikon "CF" series (the last series of "finite" objectives they made before moving to "infinity" optics), where there were no chromatic corrections performed by the eyepieces.

Unfortunately, there was no standardization. Zeiss, Leica, Olympus, and Nikon (non-CF), and most others all required what are known as "compensating" eyepieces, but each company had their own "versions" to correct their own line(s) of objectives, and they were different. If possible it is better to not "mix" one manufacturers eyepieces with another's objectives.

In the "real" world the results can vary a great deal. A mix may work out OK for viewing, but the camera tends to be unforgiving and color "fringing" may be problematic.

Will's advice is sound. Try to find eyepieces from the same manufacturer as the objectives, and from the same "period"... that is, the ones that the manufacturer intended to be used together. But try the ones you already have as well! You never know.

Charlie

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