Stereozoom 7 zoom disassembly

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viktor j nilsson
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Location: Lund, Sweden

Stereozoom 7 zoom disassembly

#1 Post by viktor j nilsson » Wed Sep 30, 2020 8:20 am

I have a Leica-branded Stereozoom 7. It works okay, but its optics have always been a little hazy, and I would like to open it up to see if I can clean it.

I need to loosen set screw (21) on the schematic below to remove the zoom knob. Am I correct in assuming that it requires an imperial hex wrench? (I don't have any at hand to test)
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apochronaut
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Re: Stereozoom 7 zoom disassembly

#2 Post by apochronaut » Wed Sep 30, 2020 1:47 pm

It is a 1.3mm by my memory but I have only taken those branded Bausch & Lomb apart. It wouldn't seem the sort of thing to change unless it was prone to stripping and they upped it to 1.5 or something like that.
1.3mm is .51 thou. The imperial equivalent is the fairly odd .50 thou., which is 1.27mm.

viktor j nilsson
Posts: 204
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Location: Lund, Sweden

Re: Stereozoom 7 zoom disassembly

#3 Post by viktor j nilsson » Wed Sep 30, 2020 2:39 pm

Thanks, apo. A 1.3mm hex wrench also seem to be what I need for loosening the helical focusing rings on the trinocular head of my Vanox AH as well, so I guess this is a good time to buy one.

I would be surprised if they changed much more than the name from the Bausch and Lomb ones.

A metric 1.3mm is probably easier to get here in Sweden.

Scarodactyl
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Re: Stereozoom 7 zoom disassembly

#4 Post by Scarodactyl » Wed Sep 30, 2020 4:27 pm

Thry made some changes to the eyepiece tubes at some point to make them like the ones on the updated sz4/sz6. I've seen a couple on sz7s but mostly the gz7. They didn't change much even on that one, hefty esd plastic body instead of metal, new eye tubes and cooler looking zoom knob. Oh, and thry used a white rubber for the dust shield arpund the eyepieces that doesn't crumble and crack like the b&l ones so that was nice.

viktor j nilsson
Posts: 204
Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: Stereozoom 7 zoom disassembly

#5 Post by viktor j nilsson » Wed Sep 30, 2020 7:01 pm

Mine's the older metal version, very similar to the Bausch and Lomb branded ones. I was actually surprised by how soft and supple the dust shields still were. I've found a local source for 1.3mm wrenches that I'll be able to pick up in a day or two.

viktor j nilsson
Posts: 204
Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: Stereozoom 7 zoom disassembly

#6 Post by viktor j nilsson » Tue Oct 20, 2020 6:32 pm

It was 1.3mm.

Good news is I got it apart. Bad news is I wasn't able to fix the haziness. I also found out that the nylon gear on the zoom mechanism was beginning to crack (still works, though). The prisms looked clear, as did all the accessible lenses. I didn't want to disassemble the upper assembly any further, so I left it at that for now. Ah well, it was fun to see what it looked like inside. It is clearly well-engineered. Nice to see all the alignment screws and thread sealer, seems like they collimated each unit pretty carefully at the factory.

BramHuntingNematodes
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Re: Stereozoom 7 zoom disassembly

#7 Post by BramHuntingNematodes » Tue Oct 20, 2020 7:24 pm

A bit disappointing you didn't find the problem. The SZ7 is a really nice scope to work with and pretty rugged from a taking apart standpoint. I had some little problems with the coaxial illuminator that I was happy to clear up.

I recently disassembled my Dynazoom binocular head to replace on of the eyepiece tubes that had a stripped pin and noticed the little window in the broken tube had a nasty layer of grease on the inside of it. Now the right eye is finally as clear as the left (unless using polarized light for some reason)!
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

Scarodactyl
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Joined: Sat Mar 03, 2018 9:09 pm

Re: Stereozoom 7 zoom disassembly

#8 Post by Scarodactyl » Tue Oct 20, 2020 8:51 pm

Take a close look at the bottom two objectives. Delamination (or more likely mold growth between lens elements) is a common failure mode.

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Stereozoom 7 zoom disassembly

#9 Post by apochronaut » Wed Oct 21, 2020 2:59 am

viktor j nilsson wrote:
Tue Oct 20, 2020 6:32 pm
It was 1.3mm.

Good news is I got it apart. Bad news is I wasn't able to fix the haziness. I also found out that the nylon gear on the zoom mechanism was beginning to crack (still works, though). The prisms looked clear, as did all the accessible lenses. I didn't want to disassemble the upper assembly any further, so I left it at that for now. Ah well, it was fun to see what it looked like inside. It is clearly well-engineered. Nice to see all the alignment screws and thread sealer, seems like they collimated each unit pretty carefully at the factory.
I have repaired a couple of cracked gears on the AO 580, a very similar problem I think, by drilling though the collar section of the gear, installing a copper pin and peining it lightly on both ends. That kept the gear from worsening and kept it fast. I can't recall exactly the B & L gears but if the crack gets big enough on the AO gears, they start to slip on the shaft. Might be worthwhile fixing when it is apart.

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