AO Stereo Star 580 collimation

[Scarodactyl]

Hi everyone. I recently got my hands on an AO 580 stereo scope. It's in great external condition and after taking it apart to clean the lenses and mirrors it produces a very nice image (somehow many of the lenses had acquired a dusty haze, though it was easily cleaned off and there was no fungus). However it is also ever so slightly misaligned, not so much that you can't use it but enough that you wouldn't want to for very long. Does anyone know if there's an easy way to make fine adjustments, similar to the ocular adjustments possible on the SZ7? Or is there a more involved process? Taking it apart to clean was fairly straightforward anyway.

[billbillt]

Hello,

I am not sure stereo scopes are covered here, but take a look.. There might be something helpful here..

https://archive.org/details/APracticalG ... imation_18

BillT

[PeteM]

If you're really lucky you might find a telltale spot where a prism etc. has slightly shifted in the upper part of the head. There is usually both a mechanical adjustment and then a dab of adhesive to hold prisms and mirrors in place. If you find the spot where that dab of adhesive is cracked, slipped, etc. it might tell you where to try tweaking things back.

Further down in the zoom mechanism some scopes just get worn and sloppy with hard use.

[Scarodactyl]

Contrary to what I've read online (here and elsewhere), the 580 does not contain any prisms, unlike the cycloptic (funnily enough, the B&L SZ7 does have prisms, exactly the reverse of some comparisons I have seen). The 580 just has four mirrors in each ocular. As far as I can tell this one never saw hard use, and everything looks nice inside and out. Thanks to that comment though I had a closer look and realized the four mirror assembly is held down by three screws, and can be adjusted somewhat if they are loosened. This certainly affects the alignment, no doubt, but it is proving to be a challenge to improve it or even return it to its previous state, as things like tightening the screws that hold the ocular together change the alignment significantly. Regardless I think this will allow me to fix it, eventually, after a lot of fiddling. Hopefully it will be worth it in the end!

[apochronaut]

Sometimes, just making sure the two mirror housings are snug enough will do the trick, if the alignment is only a little out. Check for up and down wiggle. Even a small amount of slack where they seat can cause enough mis-alignment to jump over the threshold. If there is no culprit there, check to see if the mis-alignment is uniform throughout the zoom range.
If not, then the lens columns are not moving in parallel. There is some chance for adjustment there but it is small and finicky. Tracks are held in by very small and short screws. They can come free very easily, balls fall out, etc. etc. I adjust that as a last resort and only when the collimation drifts over the zoom range. I had one once where the image collimated in the middle, then crossed over to the other side.
The front lens carrier can also be moved a bit.

An older instrument might have left the factory well aligned but a bit of wear here and there as Pete mentioned coupled with a bit of wear under the mirror housings , plus a tiny mis-adjustment of the front lens plate can be accumulative, yielding a larger than it should seem, out if collimation.

I would put the mirror set you loosened as close to perfection as you can get it first, then check those other points.

[Scarodactyl]

Thanks. I did check the housings and such, both were quite snug when I first got to them. As far as I remember it was consistent through the zoom range, fortunately pretty slight but I think I'm a bit sensitive to it since it gives me a mild headache pretty quickly (maybe psychosomatic).

At this point I'm aiming to get the mirror housing back into alignment. Moving it incautiously was, in technical terms, a Bad Idea. It's a bit of a nightmare to try to assemble all the components, so I started out testing it with various parts not screwed down tightly for quicker iterations. I got it into beautiful alignment at one point during testing (good enough that I think it would be ready for routine use), but it was back out after tightening the screws holding the ocular together. Fortunately it seems to systematically move during tightening so I should be able to get it in a position where it will be right after tightening, it's just a huge nightmare to disassemble and reassemble after each adjustment. That all said, I am hopeful that even if this wasn't the initial problem it will be able to sufficiently correct it. We'll see though...

[wabutter]

Not to put a crimp in your efforts, but the AO Stereo Star including the 569, 570 and 580 bodies were designed so they would not be serviceable with out factory collimation tools. This frustrated many local service dealers that were accustom to aligning B&L SZ stereos. Back in the day, it was often joked that when the Stereo Stars were designed they fixed the problems the of the Stereo SZ4, 6, 7 so no alignment repairs would ever be needed. Proved to be true for as long as I can remember them in production.