Will an infinity scope minus its tube lens work with 160mm optics

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Gatorengineer64
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Will an infinity scope minus its tube lens work with 160mm optics

#1 Post by Gatorengineer64 » Mon Sep 20, 2021 5:11 pm

So I have been playing around with my Axioskop Project, and so far have learned the following, as one of the heads did not have the tube lens but rather it was moved to the Optvar.

Two tublenses in series dont give good result, LOL. I put the wrong head on, one with a tube lens, plus the one in the optvar

160mm vintage optics may or may not reach focus, seems to be luck of the draw with the tubelens.

Now some questions

If the system is set up for 160 without the tube lens, then vintage 160 optics should work?

now the flip side what about infinity optics on a vintage scope (no tubelens)? wont focus?

Alexander
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#2 Post by Alexander » Mon Sep 20, 2021 5:47 pm

It will not work.

Dubious
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#3 Post by Dubious » Mon Sep 20, 2021 6:28 pm

1) If the length of the tube is right for 160mm optics (and that's not exactly 160mm--I believe you measure from the top of the objective to where the primary image is formed near but not at the top of the tube), it should work with 160mm optics, since a finite microscope is basically just a tube.

2) As for an infinity objective used on a vintage 160mm finite scope, I believe some people have reported using one as a sort of LWD objective that way. That would makes sense, as (I think) an infinity objective produces an image at infinity when the subject is a focal length away. If the subject is further away, it should produce an image short of infinity, so if the stage adjusts enough, you likely can focus it to an image. But even if you can get an infinity objective to work that way, I doubt it would work nearly as well as a finite objective in the system. Would be interesting to try, though.

Greg Howald
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#4 Post by Greg Howald » Tue Sep 21, 2021 2:27 am

For some scopes -yes. For others like mine, don't even think about it. There is no set standard for infinity scopes. Specifications differ according to manufacturer and sometimes between models put out by the same manufacturer. So, it's an iffy proposition.
Greg

apochronaut
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#5 Post by apochronaut » Wed May 18, 2022 12:26 pm

There are two considerations. One is the diameter of the optical tube, which in most cases will be adequate or at least it would be unusual for it not to be since infinity corrected microscopes in general have as wide or wider fields than many finite scopes. If you were attempting to use an older ultra wide field head, that might not work but that has nothing to do with the tube length ; just a general conversion issue.

The other is the tube length. Zeiss uses a 164.5 mm reference length for their infinity system( except the axioplan, I think), which is the shortest of all systems I have encountered, pretty close to 160 mm. However, the reference length is measured from the telan lens focal plane to the top of the eyepiece tube. The infinity space, measured from the objective shoulder to the telan lens focal plane needs to be measured and added to the reference length in order to get the total tube length. That will probably be somewhere between 75 and 100mm. So let's say your tube comes out to 250mm.
There may be some locations where you can trim some length or find some objectives that were designed for a longer tube length, or find a head that has a shorter optical path.

Another possibility.

AO used what has been described to me by a former dealer as an "apochromatic compensating lens" in the throat of the series 4 in their last 160mm system. That may not be it's correct name. It's entire purpose is still a mystery to me but possibly it was to allow for the use of longer tube met. objectives in the one instrument. It is situated roughly in the same location as a telan lens in an infinity system. One thing it does is flatten the field some and the other is it creates a longer tube. The measurement of a series 4 optical tube is 210mm, even though it uses 160mm objectives and any 160mm objective I have tried in it, seems to work in it fine.
The lens is threaded into a collar that is centerable into the space above the nosepiece. You could try one of those situated various places to extend your tube. In the series 4 the focal plane of that lens to the top of the optical tube is about 175mm but I can do a more accurate measurement if it ends up being something of interest to you. I have an extra here and can pilfer the the threaded mounting plate from a body.

Greg Howald
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#6 Post by Greg Howald » Wed May 18, 2022 4:09 pm

Mt finite objectives will work with my infinite scopes at higher magnifications above 10x. Quality of image suffers a bit. But my infinite objectives will not focus in my finite scopes at all.

apochronaut
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#7 Post by apochronaut » Wed May 18, 2022 4:54 pm

There is nothing to convert the parallel ray bundle to a convergent bundle.

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Re: Will an infinity scope minus its tube lens work with 160mm optics

#8 Post by Scarodactyl » Wed May 18, 2022 7:28 pm

Wow, that bumping post has a link inserted set to the same color as the background. Lots of spambots getting through.

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Re: Will an infinity scope minus its tube lens work with 160mm optics

#9 Post by blekenbleu » Wed May 18, 2022 10:31 pm

AO series 10 infinity scopes have their tube lens in the bottom of the head.
I removed the head, screwed in a Leitz 10x 160 objective,
got 50.4mm to m42 dovetail from RafCamera,
and stacked a bellows and digital camera body on that.
Whether it is still considered an infinity scope
or whether this is considered "working"... it does for me.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic

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Re: Will an infinity scope minus its tube lens work with 160mm optics

#10 Post by apochronaut » Wed May 18, 2022 11:24 pm

It would no longer be without the head and by removing it you can adjust the tube length to your sensor at will, so you now have a finite photo microscope.

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Re: Will an infinity scope minus its tube lens work with 160mm optics

#11 Post by dtsh » Wed May 18, 2022 11:37 pm

blekenbleu wrote:
Wed May 18, 2022 10:31 pm
AO series 10 infinity scopes have their tube lens in the bottom of the head.
I removed the head, screwed in a Leitz 10x 160 objective,
got 50.4mm to m42 dovetail from RafCamera,
and stacked a bellows and digital camera body on that.
Whether it is still considered an infinity scope
or whether this is considered "working"... it does for me.
So you're using an AO10 stand, sans head, with 160mm finite objectives in the nose, projecting to the camera?
Since the AO10 focuses by moving the nose up and down (stage and head remain static) I presume you have to focus the nose of the scope, then adjust the bellows to achieve a 160mm distance, yes?
Or have you somehow anchored the camera assembly to the arm that the nose rides on, so that the nose and camera move as a solid into (presumably at 160mm)?

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Re: Will an infinity scope minus its tube lens work with 160mm optics

#12 Post by blekenbleu » Thu May 19, 2022 8:39 pm

dtsh wrote:
Wed May 18, 2022 11:37 pm
then adjust the bellows to achieve a 160mm distance, yes?
That. The finite objective came with an AO 10, for no good reason,
but because its nose tapers down more than do my AO 10x objectives,
illuminating opaque objects was easier using the Leitz with an "angel eye" LED ring.
.. until I got an EPIStar. My eyeglasses and oculars are not friends;
I end up mostly viewing digital images, and forfeiting the head was no great sacrifice.

Until getting a Fisher 4x, an infinity Meiji S.PlanM5X was used as a "finder" for the Leitz 10X 160.

It would seem that any infinity scope without tube lens becomes finite
or unusable without eyepieces that focus near infinity...
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic

dtsh
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Re: Will an infinity scope minus its tube lens work with 160mm optics

#13 Post by dtsh » Thu May 19, 2022 10:11 pm

blekenbleu wrote:
Thu May 19, 2022 8:39 pm
My eyeglasses and oculars are not friends;
I end up mostly viewing digital images, and forfeiting the head was no great sacrifice.
I certainly understand that, I find these days as I use the camera more and more, a monocular design as I have one some of my scopes is no impediment to their use. I just need to get a better illuminator to use for the ones without built-in Koehler.
blekenbleu wrote:
Thu May 19, 2022 8:39 pm
It would seem that any infinity scope without tube lens becomes finite
or unusable without eyepieces that focus near infinity...
Well sure, if you remove the telan lens from the equation (bottom of the head on an AO10 for those not familiar) and set the distance to 160mm you've effectively made it finite (as you know). It's a creative solution to the problem using what you have.

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