60X plain or plan?

[Dale]

My not yet delivered AO-10 scope will have 4 10 40 100 infinity plan obj's. Not wanting to hassle with oil, I like JimT's photos
of his 60X results. The plain model is $60, the plan model is $100. I have no basis for comparison, so I ask is it a no brainer
to go another $40 and get the plan model? The underlying reason I bought this scope were the quality obj's, so to limit its
top end for a few dollars seems unreasonable.

[gekko]

You are limited to AO infinity objectives (probably watch for them at eBay) , as you will not get acceptable results from objectives designed for finite tube length (or even infinity corrected objectives of other brands).

[Dale]

I understood your answer, didn't like it, but understood it. Thank you very much.
Dale

[gekko]

I understood your answer, didn't like it, but understood it. Thank you very much.
Dale

Sorry about that, but I didn't want you to buy the wrong objective. Last night I looked on ebay, but although I didn't see suitable 60x infinity objectives for sale, the AO objectives appear to be very reasonably priced, so I think it will be a matter of patience. Having said that, to my way of thinking a 60x will be harder to get good results from than a 40x or even a 100x oil-immersion, and, also to my way of thinking, the 40x will have sufficient resolution for almost everything but bacteria (where even a 100x will not give much detail) and resolution of diatom details for the sake of resolving them (but since I don't have a 60x, you can argue that I don't know what I may be missing...). I found the following link which might be useful (as it gives important details of AO objectives, including part numbers, whether finite or infinity, and parfocal distances):
https://user.xmission.com/~psneeley/Per ... ctives.htm

[JimT]

Dale, most times the 40x is sufficient but I like my 69x as it is much less hassle than the OI.
I also just bought a 20x which I like when 10x is not enough and 40x is too much. You might want to consider that as your first upgrade.

[Crater Eddie]

I also just bought a 20x which I like when 10x is not enough and 40x is too much. You might want to consider that as your first upgrade.

This is what I am considering, and for those very reasons.
CE

[Dale]

Thanks everybody for the outstanding advice. Last night I scoured all the manuals at Xmission, then scoured Ebay.
No results except for a darkfield going for $1500! I should have mentioned my scope will also have a set of 18X eyepieces,
so with a 20X I should have a lot of quality resolution flexibility. I'll go check Ebay for a 20X.
Dale

[JimT]

Dale, best advice I can offer is use the scope for a while before you buy any upgrades. Always fun to think about them and "Window" shop but get use to the scope first.
Let us know when you get it and your "First light" (Astronomy term) observations.

[75RR]

I should have mentioned my scope will also have a set of 18X eyepieces, so with a 20X I should have a lot of quality resolution flexibility. I'll go check Ebay for a 20X.

Think you will find 18x does not increase resolution, 10x eyepieces are what you want. Any increase in meaningful magnification should really come from your objectives.

[gekko]

I should have mentioned my scope will also have a set of 18X eyepieces, so with a 20X I should have a lot of quality resolution flexibility. I'll go check Ebay for a 20X.

Think you will find 18x does not increase resolution, 10x eyepieces are what you want. Any increase in meaningful magnification should really come from your objectives.

Yes and (possibly) no: quite true if you have 20/20 vision. With my poor vision, the increase in eyepiece magnification allows me to see what the objective resolves so to me it is not empty magnification. I use 15x eyepieces + 1.25 magnification in the head ~ 19x. Another advantage in my case is that the field of view becomes smaller and just a tad larger than what the camera sees, a distinct advantage since my camera does not display directly to the computer.

[75RR]

Yes and (possibly) no:

Would I be wrong is I said that your (15x X 1.25) = 19 allows you to see the magnification that your objectives are providing rather than anything extra?
I mention this because I have the impression that Dale seems to think that going from 18x eyepieces to 20x eyepieces will provide more effective magnification.

[gekko]

Yes and (possibly) no:

Would I be wrong is I said that your (15x X 1.25) = 19 allows you to see the magnification that your objectives are providing rather than anything extra?
I mention this because I have the impression that Dale seems to think that going from 18x eyepieces to 20x eyepieces will provide more effective magnification.

You are exactly right. And the converse is also true: with my poor vision, I am unable to see the detail that the objectives resolve if I use 10x eyepieces. But, to carry the argument further, even with 20/20 vision, if you use the rule of thumb of 1000 X NA, for a 10x/0.25 objective, empty magnification will "start" at 1000 X 0.25 = 250x total, so an eyepiece of 25x will "pass" the empty magnification criterion for that objective.

[Dale]

Ooops. My bad. The 2nd eyepiece power is 15X, not 18. What I meant to say is that with 10 and 15X eyepieces and the added 20X
objective would give a nice magnification spread up to 600X. The 60X would add one more power of 900X, which most feel would give
a lesser image quality. I do wear glasses and I don't care to get intimate with virus and bacteria, so I'll take the oft received advice
and get some experience. I was encouraged to learn from several highly respected sources that a modern objective may work
with the AO as shims are available to correct minor focus problems.
Dale

[gekko]

Yes and (possibly) no:

Would I be wrong is I said that your (15x X 1.25) = 19 allows you to see the magnification that your objectives are providing rather than anything extra?
I mention this because I have the impression that Dale seems to think that going from 18x eyepieces to 20x eyepieces will provide more effective magnification.

You are exactly right. And the converse is also true: with my poor vision, I am unable to see the detail that the objectives resolve if I use 10x eyepieces. But, to carry the argument further, even with 20/20 vision, if you use the rule of thumb of 1000 X NA, for a 10x/0.25 objective, empty magnification will "start" at 1000 X 0.25 = 250x total, so an eyepiece of 25x will "pass" the empty magnification criterion for that objective.

My last statement is not quite true in practice because one does not usually illuminate the full aperture of the objective, about 70% illumination being more typical. So redoing the calculation for the 10x/0.25NA objective, and using the criterion of 1000 X NA as the threshold for empty magnification, a total magnification of 1000 x 0.2 = 200x will be within the "useful magnification" realm, and a 20x eyepiece would still deliver useful magnification with that objective. [The 0.2 figure for NA is an approximate overall value based on objective NA = 0.25 and condenser NA = 0.25 X 0.7 = 0.175].

[75RR]

Hi Dale, have not seen a post lately on your AO –10. Hope you are too busy having fun with it to post.
Looking forward to an update from you.

[Dale]

Haven't seen it yet Been busy collecting supplies, scouring Ebay for a 20X, printing the manual,
building a vernier microtome, looking for a decent affordable book that wasn't obsolete or written for
6 year olds, buying slides & slips & pipettes & gem tweezer & an led stage light. I'm not rushing this,
the seller was so patient with my numerous questions, and I have since verified that this is one fine
scope, well worth waiting for. Besides, the hospital I worked for just cancelled my retirement and
scheduled me for 3 days a week. That will more than pay for the scope!

[75RR]

Besides, the hospital I worked for just cancelled my retirement and
scheduled me for 3 days a week. That will more than pay for the scope!

My previous/concurrent interest: "Knots"- is way cheaper than microscopy as a hobby!
All one needs is a couple of short lengths of rope.
So your retirement postponement is well timed. :)

Finding specific additional objectives is more of an add to wish list thing; I find they do turn up ... eventually.
Looking forward to seeing photos of your microscope when you finally get it; in the My microscope section.

[Dale]

Oh I beg to differ on the knotty comment. When I delved into marlinspike seamanship the lengths
were long and braided and fastened to a 30 foot sloop! Never could fabricate a monkeyshead.
The scope arrived a few hours ago, just as the wife and I were heading out to see American Sniper.
She is holding the box captive til I recaulk the sink. Women!
Dale

[75RR]

When I delved into marlinspike seamanship the lengths were long and braided and fastened to a 30 foot sloop!

If your rope comes with a boat tied to the end of it; I can see how that could be expensive.

How is the caulking coming along?

[Dale]

Confucious say boat is like woman: hull is cheap, the rigging will kill ya!
The scope arrived, and the P.O managed to break the foot of the frame, so while I'm getting
that straightened out I can start the caulking.
Dale