drexelpbp
sage
Reged: 01/21/08
Posts: 269
Loc: Phoenixville,PA
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Hi
I am having problems with my Zhumell 20 x 80 binoculars.
I'm sure you have heard this before - they don't seem to be properly collimated. They work fine for terrestrial use but it is tough to get a single image for astronomical use.
Maybe someone can point to some information on how to collimate these - if that can be done.
Also I have another problem with them - they have a center post which is used to mount them to a tripod. It is tightened, to keep it from pivoting, with a knob that has some nylon at the end. It just won't tighten enough to keep the binoculars from pivoting - obviously this is very annoying. Any idea on how to fix this??
Thanks for any input.
Gary
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Orion 8" intelliscope
Celestron CF 8' SCT
Celestron 8SE
Celestron C80ED
Orion ST120
Orion ST80
Orion 120 f/8.3
Orion Skyview Pro Deluxe 90 f/11
Celesrton SP C102
Celestron SP 150N
Various Televue, Baader, Orion and other EPS
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Erik D
Post Laureate
Reged: 04/28/03
Posts: 3196
Loc: Central New Jersey, USA
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Gary,
You may find some of the techniques discussed in this thread helpful: Binocular Collimation or Conditional Alignment
Some giant binoculars have prism adjustment screws that are easily accessible. You can use them to merge images and achieve "conditional alignment". If the Zhumell you are having problems with is a recent purchase I suggest returning them to the seller for adjustment.
ERik D
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drexelpbp
sage
Reged: 01/21/08
Posts: 269
Loc: Phoenixville,PA
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Thanks, Erik - that is a great thread.
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Orion 8" intelliscope
Celestron CF 8' SCT
Celestron 8SE
Celestron C80ED
Orion ST120
Orion ST80
Orion 120 f/8.3
Orion Skyview Pro Deluxe 90 f/11
Celesrton SP C102
Celestron SP 150N
Various Televue, Baader, Orion and other EPS
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hallelujah
Carpal Tunnel
Reged: 07/14/06
Posts: 2156
Loc: Rocky Mt. High Colorado
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Quote:
Also I have another problem with them - they have a center post which is used to mount them to a tripod. It is tightened, to keep it from pivoting, with a knob that has some nylon at the end. It just won't tighten enough to keep the binoculars from pivoting - obviously this is very annoying. Any idea on how to fix this??
Thanks for any input.
Gary
Gary,
I have three giant binoculars and all three pivot back and forth after tightening. The nylon bushing merely keeps the binoculars from sliding unnecessarily along the center rail.
You might find it even MORE annoying if it didn't have the ability to pivot. 
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Celestron Traveler 8x25 & B. & H. 8x40 FC JAPAN & Revue 10x50 CF Porro FC JAPAN &
Pentax 12x50 PCF WP II FMC & Pentax 16x60 PCF WP FMC &
Pentax 20x60 PCF WP II FMC & Orion 12x63 Mini Giant FMC JAPAN &
SPECTRUM I 20x65 FC JAPAN &
Orion 15x70 Little Giant II FMC JAPAN & Orion 20x70 Little Giant II FMC JAPAN
Orion 16x80 Giant FMC JAPAN & Orion 30x80 MEGAView FMC JAPAN
Barska 30x80 X-Trail LW FC & Burgess Optical Series II 20x90 FMC
Hallelujah! For the LORD God Omnipotent Reigneth
Edited by hallelujah (11/23/08 07:25 PM)
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drexelpbp
sage
Reged: 01/21/08
Posts: 269
Loc: Phoenixville,PA
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Thanks, I was not aware of that.
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Orion 8" intelliscope
Celestron CF 8' SCT
Celestron 8SE
Celestron C80ED
Orion ST120
Orion ST80
Orion 120 f/8.3
Orion Skyview Pro Deluxe 90 f/11
Celesrton SP C102
Celestron SP 150N
Various Televue, Baader, Orion and other EPS
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donniesoprano
member
Reged: 07/23/08
Posts: 39
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Gary,
I just picked up a pair of these on the cheap-cheap on Astromart last week. I was hoping that all it would take is some tweaking of the collimation screws to get the prisms lined up, but unfortunately that didn't work.
I've taken them apart down to the prism assemblies and I can now see why the screws didn't work on mine. The prisms are in very, very tight and the screws will push them, but the prisms do not fall back on the screws if the screws are reversed.
I'm working on getting these things serviceable and will probably post a thread on how I did it when I'm done, if I'm successful.
I agree with the poster above, though, if you can just return them (especially these) just do that. From looking at the innards, I'm not sure very many people will want to attempt the surgery I'm doing.
ds
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Nick Lloyd
He asked for it
Reged: 10/24/06
Posts: 2156
Loc: cincinnati
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ds- many people would appreciate any photos and information you gather regarding the servicing of these 20x80s. I use mine often and (once collimated) find them be good value for the money.
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"The best scope is the one you use." -rcg
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donniesoprano
member
Reged: 07/23/08
Posts: 39
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Will do.
I've started a new thread here: http://www.cloudynights.com/ubbthreads/showflat.php?Cat=0&Number=2768513&page=0&view=collapsed&sb=5&o=all&fpart=&vc=#Post2768513
for my own 'project' with these binos.
ds
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Wrathchild
super member
Reged: 10/09/07
Posts: 131
Loc: Charlotte, NC
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What are the general opinions on these binos? I'm looking for a good set to use for quick viewing sessions now that it's getting too cold to set up the 10". These are available at a super price, assuming the quality is decent.
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Chris
All that is required to enjoy astronomy is a clear night and the desire to learn.
Zhumell 10" Dobsonian
Celestron 15x70 SkyMasters
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binman
member
Reged: 09/16/08
Posts: 134
Loc: UK
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the general opinion on these bino's seems to be you have to conditionally align them your self which would suggest the quality is far from decent.
the word collimation seems to pop up in every thread regarding these bins eventually
Edited by binman (11/30/08 10:37 AM)
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astrokido
space wanderer
Reged: 06/09/08
Posts: 663
Loc: Phoenix, AZ
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I doubt there's a "general" opinion since experiences have been so diverse, from "complete trash" to "they're great". Do a search and you'll run into hundreds of posts on the Z 20x80s. I got a pair for cheap assuming I could still use the optics if all else failed at still a decent price. It turned out I was just able to get them collimated at the end of their prism adjustment. It's pretty much a gample and you'll have to figure out what sort of tweaking the particular pair you get requires. I'd recommend two steps:
1) align each side individually by looking through the objective end and center the small eyepiece circle so that each half ends up roughly collimated. Look in particular to center the prism edges you can just see. Then evaluate the image quality of each half, mine was excellent. All optic surfaces are coated with a nice blue anti-reflection coating.
2) see how far the two eye views are off, mine barely had any overlap at all after step 1). Here you realize how horrible the construction quality is. If you're lucky, the prism screws will have enough travel to align the two views. If you open them up, you start seeing metal shavings, grease waiting to fall on inside optic surfaces, and you realize you got what you paid for.
Good luck!
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- Gill C. - Celestron Cometron CO-100, 10x25, 20x80, Binochair, Nikon D40
The Night Sky Atlas: www.nightskyatlas.com
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