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Zhumell 20x80 how to collimate?

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#1 SkyDan

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Posted 30 June 2020 - 09:02 AM

Hello,

 

New guy here, my first post.

 

 recently purchased used Zhumell 20x80 binoculars from Amazon (with 30 day return policy), price was too good to pass but now I understand why. They have the dreaded double vision. I can fine tune IPD, and everything else seems ok. So before I send them back, I'd like to try to get them adjusted correctly if this is even possible.

 

I checked the forum and there are some really old posts regarding the Z220x80 but have not found any clear instructions on how to collimate these binoculars. I did read about ajustment screws, pealing back the plastic. I removed the plastic around the eye pieces and don't see any ajustment screws.

 

Can anyone confirm if these can be adjusted and if so, help me out with some instructions on how.

 

Thanks!

 

IMG_4521.jpeg



#2 Mike G.

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Posted 30 June 2020 - 10:04 AM

"Conditional alignment" (using the prism tilt screws to collimate) will make the binos work, but only for the particular IPD you adjusted them to.  other people with different IPDs will still see double stars.  if you want to keep them and have them properly collimated, send the to Cory Suddarth at SOR in Oklahoma.  easier and cheaper to send them back to Amazon and see if they can get you a good pair.



#3 Rich V.

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Posted 30 June 2020 - 10:57 AM

Those binos appear to share the same lightweight prism build as the Oberwerk LWs; here's their link to getting them conditionally aligned.  They will end up being aligned at the user's individual IPD but not truly collimated, so may not be aligned for others using the binos at other IPDs.

 

https://oberwerk.com...mariner-series/

 

Be careful; the screws are tiny and easily stripped or broken. Use a jeweler's screwdriver that fits exactly. They will provide enough movement to make small alignment adjustments but if a prism has been knocked out of position by a shock during transit, you will not have enough range to re-align them.

 

Rich


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#4 SkyDan

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Posted 30 June 2020 - 10:59 AM

As mentioned I have 30 days to return with prepaid shipping (Amazon prime). If I do return them I'll most likely look at different ones and avoid them sending another set with same issues.

 

I found a photo on the web showing where the adjustment screws are located under the rubber covering and have tried to adjust with some success. Using trial and error I have the binos pointed to a distant object (daylight here) and turning the screws until the double images merges into one. Seems like the left screw moves vertically and right side adjustment screw moves horizontally. Definitely better than they were but still feels a bit off. This may be best I can do, again for the price I paid I may keep them. Any tips on how to collimate appreciated... 



#5 Bortle9

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Posted 30 June 2020 - 02:46 PM

Any tips on how to collimate appreciated... 

The alignment screws, as you've likely discovered, move the prisms at 90 degrees to each other but rotated 45 degrees from up, down, left, right. It will be important that the IPD remains locked/constant as you adjust the screws. It was my inability to keep the IPD locked during adjustment on my Celestron 15x70's that I threw in the towel and bought an Obie. Also, you may find it easier to point to a nice bright star at night while adjusting. You may find a point source easier to merge. Finally, look away frequently during the conditional alignment process so your eyes don't naturally correct the image.

 

I enjoyed the Celestron's as a beginner so it was way past the 30 day return window, but I now have two 15x70 monoculars. (Well, I will when I get around to tearing them down, but that's another post!)



#6 pat in los angeles basin

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Posted 30 June 2020 - 02:57 PM

The trick (which I haven't figured out yet) is to find if one or both sides the prisms have shifted. Could be one side or the other or both. If you make the adjustment to the wrong side, then all other IPD settings will be worse to unusable. Some people have commented that the image on the eyepiece can sometimes resemble a catseye when viewed on the eyepiece at a distance. I haven't seen that . If you do manage to get an alignment that's agreeable it's commonly called "conditional alignment" and that's fine if you are the only user. If you have managed to pry loose the rubber armor to gain access to the prism tilt screws, will amazon still give you a refund/replace?

                                                                                                              Regards, Pat



#7 Chuck2

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Posted 30 June 2020 - 03:07 PM

Per Oberwerk instructions posted above, during daylight find a house or building at distance. Use window frames, gutters and chimneys to check both vertical and horizontal collimation. 

 

After you feel alignment is close, at night point at a bright star and tweek the final adjustment. Like mentioned above, the collimation may be 'conditional' for your eyes only, but how often are you sharing your binos?

 

Relatively simple procedure, essential maintenance for some binos after a year or two of field use.



#8 Jon Isaacs

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Posted Yesterday, 04:19 AM

My thinking:

 

If you keep these, this will not be the last time you need to align these binoculars.  If you want some binoculars that you can trust, binoculars you can take with you to a dark site and be confident that they will perform their best, I would return them and look for something better. 

 

Jon


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#9 Foss

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Posted Yesterday, 09:00 AM

^^^ x2




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