KerryR
Pooh-Bah
Reged: 12/05/07
Posts: 1172
Loc: SW Michigan
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Hi all,
I recently aquired a used Stellarvue M7 alt-az mount, and tried it for the first time last night with my Meade ed/apo 127 (the old one).
The azimuth movement was very sticky when first pushing the scope; it'd grip, then release, causing me to overshoot the target. Also, there appears to be some play in the azimuth axis, while there is none in altitude.
Everthing feels smooth and stick free when there's not scope on the mount, but add the scope and the azimuth is virtually unusable.
I don't think I'm supposed to need a counterweight with the reasonably light scope (kinda defeats the advantage of an alt az mount...). but perhaps that's the issue. The thing is huge; I can't see any reason it shouldn't be capable of super-smooth movements...
Any thoughts?
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Kerry
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Tom D.
Carpal Tunnel
Reged: 11/29/04
Posts: 1732
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Quote:
Any thoughts?
Get a DiscMounts. The DM-4 will handle your Meade 127 quite nicely.
Sorry, couldn't resist  . You may want to post this question in SV's yahoo group.
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Stellarvue SV105 (TMB/LZOS f/6.2)
DiscMounts DM-4 w/Sky Commander XP4
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boydd
sage
Reged: 12/07/07
Posts: 237
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The counterweight is necessary.
"Because it Works"
Dave Boyd
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Tom D.
Carpal Tunnel
Reged: 11/29/04
Posts: 1732
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Quote:
The counterweight is necessary.
"Because it Works"
Dave Boyd
Really? For a maybe 20+lb scope? For $895 (head only), that's fairly sad.
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Stellarvue SV105 (TMB/LZOS f/6.2)
DiscMounts DM-4 w/Sky Commander XP4
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KerryR
Pooh-Bah
Reged: 12/05/07
Posts: 1172
Loc: SW Michigan
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Hopefully, I don't need a counterweight-- kinida defeats one of the benefits of alt-az mounting.
I noticed some play in the azimuth axis. Took the thing apart, cleaned, re-lubed, re-assembled minus the azimuth slack, seems much better. Haven't had clear skies to test it on, but it feels fine now. There's no end in sight for clouds, so it may be a while before I really know.
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Kerry
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pennyandchris
professor emeritus
Reged: 01/30/07
Posts: 646
Loc: Horsham, England
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I always use a counterweight with my Mak on the alt-az - without it, movement becomes erratic - sticking then releasing just as you describe - but there again, mine is only a £300($450)-ish mount.
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Orion UK OMC140 Mak Cass
TeleVue Ranger
Coronado Ha and CaK PSTs
Meade LXD75 mount
Ambermile alt-az mount on wooden surveyors tripod
Manfrotto 074 photo tripod with 501 head
+ various binocs
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7331Peg
professor emeritus
Reged: 09/01/08
Posts: 734
Loc: North coast of Oregon
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I've got the same mount and haven't had any problem with the azimuth motion, but I've got two scopes mounted on it - one is twenty-two pounds, the other about fifteen. With the 20 pound weight of your scope, you're very close to the point where you may need some weight on the other side - shouldn't need more than five pounds - or a second scope.
Looks great with two scopes on it. I call it double-barrel astronomy! 
John
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ottovonrotton
member
Reged: 01/01/09
Posts: 65
Loc: Where is Port Perry?
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Hello, I use an M6 the forerunner to the M7 and I use an antares 127/1200 at about 21lbs. I do have to counterweight the otherside with at least 5lbs (also have duo setup). I also set the mounting rings as wide as I could as this really made a difference in balance.
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Go Modern, Go Gas, Go Bang!
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Starlighter
Post Laureate
Reged: 08/03/07
Posts: 4494
Loc: Sunny California
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I use the Orion Skyview dual head AZ mount. It works as advertised. The first one I had couldn't be properly locked down so I returned it for a refund. Then after I was notified by Orion that they had addressed the problem, I took the chance and ordered another. I was pleased when I discovered that this one can be locked so that when a lightweight eyepiece is exchanged for a heavier one necessitating a rebalance, I don't need to worry about the scope or scopes doing a serious nosedive. The Orion is well made. Stability is excellent. Once proper balance is reached, I can slew by merely lightly touching the diagonal.
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Celestron C4-R 102mm achromat
Celeston Nexstar 6SE SCT
Meade 80mm APO Triplet
Televue NP-101
Televue TV-85
Vixen A70Lf
Vixen A80Mf
William Optics 66mm Zenithstar Patriot
Celestron CG4 EQ mount
Orion Skyview Pro AZ mount
Vixen Portamount
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Starlighter
Post Laureate
Reged: 08/03/07
Posts: 4494
Loc: Sunny California
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The Orion:
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Celestron C4-R 102mm achromat
Celeston Nexstar 6SE SCT
Meade 80mm APO Triplet
Televue NP-101
Televue TV-85
Vixen A70Lf
Vixen A80Mf
William Optics 66mm Zenithstar Patriot
Celestron CG4 EQ mount
Orion Skyview Pro AZ mount
Vixen Portamount
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KerryR
Pooh-Bah
Reged: 12/05/07
Posts: 1172
Loc: SW Michigan
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I don't need a counterweight with the same scope (old Meade ED/Apo a27) on my Unistar, and it tracks quite well at 250x. I really hope it's not necessary on the M7; the thing is quite a beast as it is. Wouldn't want to have to fiddle with a weight-- might as well go equatorial if that's the case, and get motorized tracking. Doesn't feel like it it has a problem now, after tightening the azimuth axis. I won't really know 'till I get a chance to test it under the stars...
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Kerry
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