Help needed: disassembling an SMZ1500

[Scarodactyl]

I recently picked up an SMZ1500 zoom body on eBay for a pretty low price. It came with a planapo 1x objective so I already got my money's worth, but I was hoping I might be able to fix the zoom body as well and make it an insane deal. Nikon's smz1500 has a whopping 15:1 zoom ratio which I have high hopes for, but this one's zoom function is broken. The knob spins but it doesn't engage. Otherwise the optics are clear, and when putting a mostly-compatible scienscope head on it I am able to resolve a very nice image, just not change the zoom setting. That leads me to believe it may indeed be fixable, but I have to take the plastic shell off to see what's going on, and so far I haven't had much luck. The two halves of the shell snap together at the center of the microscope, and are held on with screws (some of which were already missing, suggesting someone has tried this before)--however, while removing the screws allows them to be pulled apart, neither half can move far because the zoom knobs are in the way. Does anyone have any idea how they might be removed? There are two tiny setcrews on the knobs, but as far as I can tell they just allow the zoom indicator ring to freely rotate, presumably so that can be easily reset.
Here are some images of the scope:



Thanks!

[MichaelG.]

Crass as it sounds ... you may find that the knobs just pull off
Splined, or 'D' shaped, shafts are common on audio equipment and domestic appliances.
... In principle there is no reason not to use them on a stereo microscope.

MichaelG.
.

Caveat: The emphasis on may means "proceed with due caution"

https://www.nikoninstruments.com/conten ... MZ1500.pdf
http://bwoptics.com/newsend2.asp?id=2 illustrates the optical layout

[75RR]

There are two tiny setcrews on the knobs

Remove them before attempting to pull the knobs off.

[MichaelG.]

There are two tiny setcrews on the knobs

Remove them before attempting to pull the knobs off.

+1 for that ^^^

[MicroBob]

Occasionally there is a second set screw behind the set screw.
There might be caps on the outside of the knob, fitting so well that they are difficult to see.

[Scarodactyl]

Thanks everyone! That was it, there was a close-fitting cap on thr knob that pulled off to reveal two setscrews. Loosening them allowed the knobs to slip offm the whole thing still wouldnt come all the way apart, but (and this is an early Christmas miracle) the problem was obvious: the gear on the zoom shaft was shifted out of place so ot just barely grazed the gears of the zoom assembly. A gear hekd to the shaft by a single set screw. After some awkward reaching with an allen wrench to loosen it, shove it back into place and tighten it it is working great! I can't believe I got something this nice for this price. Now I just need to adapt a focus block on and find a head. I habe a c-series scienscope whose head is mechanically compatible, but it isn't a perfect fit, so the quest continues for now.

[MicroBob]

Nice to hear of your success. Practical capabilities often make the difference between scrap and a valuable object. This is especially true with used microscopes.
This must be a really impressive stereo microscope! Do you know the aperture value of the objective?

[Scarodactyl]

Unfortunately the NA of the objective isn't too likely to turn heads. The 1.6x planapo option only has an NA of 0.21, so the 1x is significantly lower than that. Still, it does take some optical wizardry to get an objective to behave well across that whole zoom range. But it should have good color correction and that zoom ratio and range are fairly ideal for gemological subjects. I'm still struggling with shipping issues on my Leica Z16 to upgrade my m420, so in the mean time this may upgrade my photographic capabilities too.

[MichaelG.]

Unfortunately the NA of the objective isn't too likely to turn heads. The 1.6x planapo option only has an NA of 0.21, so the 1x is significantly lower than that.

Numerical Apertures are listed in the brochure that I linked ...

MichaelG.

[MicroBob]

My old Leitz Großfeld stero microscope has objectives up to n.a. 0,12, my old Olympus SZ III as far as I know 0,085. So 0,21 is quite a lot for a stereo microscope! I think there are stereo microscopes with up to n.a. 0,6 today, but this additional potential is probably difficult to use, apart from the price of the instrument.
It must be nice to have such a wide magnification range available at the twist of a knob.

Does you zoom work smooth? There might be a reason for the cog leaving it's place.

[Scarodactyl]

Numerical Apertures are listed in the brochure that I linked ...

MichaelG.

Thanks, that is convenient. This is a normal planapo 1x, not an hr objective, so it's only 0.1. Probably beats out my stereozoom 7 anyway.

Does you zoom work smooth? There might be a reason for the cog leaving it's place.

It does work smoothly as far as I can tell. There is a sizeable dent on the front filter thread of the objective, so i suspect it was dropped.

[MichaelG.]

This is a normal planapo 1x, not an hr objective, so it's only 0.1.

Still a very, very, capaple instrument by the looks of that brochure.
... I wish you great joy with it.

MichaelG.