Olympus BX stage keeps drifting down, "focus shifting".

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adamski
Posts: 33
Joined: Fri Oct 21, 2016 11:36 am

Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by adamski »

Thanks Enrico, yes I am using halogen 12V 100W lamp. I am using BX53 stand just to clarify, very interesting pointers about provis models, well I really like 53 because it has small footprint and does not take much space on my very busy table!
I will take a look at LED lighting as an alternative, many thanks.

enricosavazzi
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Location: Borgholm, Sweden
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Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by enricosavazzi »

adamski wrote:
Fri Oct 09, 2020 2:13 am
[...] I am using BX53 stand just to clarify, very interesting pointers about provis models, well I really like 53 because it has small footprint and does not take much space on my very busy table! [...]
Indeed, the Provis stand weighs north of 50 kg "naked", needs a strong table, and most functions are motorized so it needs multiple external electronic controllers (unless one uses the manually operated condensers, objective turrets etc. for the BX). In retrospect I am glad I never got mine because if anything goes wrong with the electronics, then I am stuck with an unusable scope that takes four times the desk area of a BX.
--ES

pbraub
Posts: 77
Joined: Fri Feb 02, 2018 1:23 pm

Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by pbraub »

I tested drift on my bx43 (with (30w equivalent) led light source) on two occasions. In both it lost focus within a 15-20 min period (no-touch and no vibrations, i was out of office) with a 40x/0.95 objective. The scope likely was in thermal equilibrium (it was running all day and there was little to no sun on it). However I have not yet locked the z-axis completely.

Would doing stacks and correcting for the drift in silico later on work for you?

pbraub
Posts: 77
Joined: Fri Feb 02, 2018 1:23 pm

Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by pbraub »

enricosavazzi wrote:
Fri Oct 09, 2020 9:37 am
In retrospect I am glad I never got mine because if anything goes wrong with the electronics, then I am stuck with an unusable scope that takes four times the desk area of a BX.
One of our Oly reps told me a story about an ax70 dopping from a warehouse storage shelf, knocking a hole in the concrete - he said it broke the cast metal frame on the impact site but other than that it was still working. I bet the bx3 series would not survive this :|

Macro_Cosmos
Posts: 993
Joined: Mon Jan 15, 2018 9:23 pm
Location: Sydney

Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by Macro_Cosmos »

pbraub wrote:
Fri Oct 09, 2020 12:32 pm
enricosavazzi wrote:
Fri Oct 09, 2020 9:37 am
In retrospect I am glad I never got mine because if anything goes wrong with the electronics, then I am stuck with an unusable scope that takes four times the desk area of a BX.
One of our Oly reps told me a story about an ax70 dopping from a warehouse storage shelf, knocking a hole in the concrete - he said it broke the cast metal frame on the impact site but other than that it was still working. I bet the bx3 series would not survive this :|
Glad it was merely a hole in the concrete, can you imagine that thing hitting someone? It weighs more than 50kg. A contact of mine has 3 of those, I'd love to fly over and try it, once this silly virus is over I guess. He's happy to sell a couple, but how on earth would I get it back home?

I would love to have an AX70, getting parts for it is a nightmare however, and everything is motorised, so the setup is going to be huge...
It's an engineering marvel for sure, just like that big Zeiss Axioscope, but it is also discontinued, barely any good used units either. So I guess it was either unsustainable as a product or very unpopular, or both.

PeteM
Posts: 23
Joined: Sat Jan 05, 2019 12:06 am
Location: West Coast, USA

Re: Olympus BX stage keeps drifting down, "focus shifting".

Post by PeteM »

In addition to the possible causes noted above, thickened grease along the stage slide (a series of crossed bearing cylinders) can be the culprit. There is always some backlash in a geared system and (at least on my two BX scopes) the weight of the stage is what settles it to the lowest point when you fine focus.

If your out of focus problem stops after a while (and settles more quickly, then stops, with a higher temperature) it could be thick grease is damping it's fall. If it continues to fall beyond what might be reasonable backlash, then it's likely one of the earlier-noted posibiliities.

It's not especially hard to disassemble the slide and clean and lube it with a light grease.

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