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TMB 130mm and Losmandy GM 8 Mount

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#1 mountain monk

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Posted 01 February 2010 - 03:23 PM

Will the GM 8 mount handle a TMB 130mm? Visual use only. Perhaps a binoviewer too.

#2 GShaffer

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Posted 01 February 2010 - 03:25 PM

Yep....

#3 hudson_yak

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Posted 01 February 2010 - 03:49 PM

I didn't think it handled my 100ED very well (similar focal length to what you're talking about I think) so if it were me I'd want a G11 for that. In my case I downsized the scope instead, the new one works very nice on the GM-8.

At the very least you'll want something other than the LW tripod for it.

Mike

#4 WilRobinson

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Posted 01 February 2010 - 03:54 PM

Yes, It works well but you need the 11 lbs. counter weight.

#5 SteveC

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Posted 01 February 2010 - 03:55 PM

I know someone who had a 5" TV scope on a GM8, and he wasn't a happy camper. Lot's of shaking.

#6 RAKing

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Posted 01 February 2010 - 04:13 PM

Mine worked great. :) The picture shows it on an A-P Portable pier, but I also used it on the regular tripod a few times.

Just check your balance. My DEC worm had some extra play in it and I had to shim it a bit tighter. I also made sure the scope was a bit heavy on the East side and that took care of any RA gear play.

Ron

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#7 David Pavlich

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Posted 01 February 2010 - 05:00 PM

I think it'll be fine, but just make sure you get the balance real close. That will ensure that the motors aren't straining.

David

#8 mountain monk

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Posted 01 February 2010 - 05:11 PM

The reason I asked is that in his review of the TMB 130mm, Tom Trusock said "A GM8 would do in a pinch, but I feel that's really pushing it." The scope, all decked out, weights 23 #; the binoviewer plus lenses is a few pounds more. I was told that the Losmandy ratings tended to be conservative, and I think that the GM 8 rated at 30#. All that indicated to me that the outfit might be close to the line. On the other hand, I really don't want to deal with all the weight of the GM 11.

Thanks for your comments.

mm

#9 SteveC

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Posted 01 February 2010 - 06:21 PM

Hi Ron,

I suspect that your GM8 works much better since it's on a G11 tripod.

#10 GShaffer

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Posted 01 February 2010 - 07:16 PM

The GM-8 on the regular tripod will do an acceptable job with the 130 the OP asked about.....if you keep the tripod collapsed, when you start extending it is when you see loads like this one start to dissappoint you.

#11 RAKing

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Posted 02 February 2010 - 11:09 AM

Hi Ron,

I suspect that your GM8 works much better since it's on a G11 tripod.


Yes, I would definitely recommend the A-P Portable Pier or a G11 tripod as better platforms for this rig.

But I also used the stock GM-8 rectangular tubed version a few times with no problems.

My TMB 130 weighed 25 pounds with rings, dovetail, Telrad, diagonal, and an eyepiece. With careful balancing, it worked very well for visual observing. :cool:

Cheers,

Ron

#12 gnowellsct

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Posted 02 February 2010 - 04:44 PM

I use a G11 for my FS128 and I think it is muy bueno. Wouldn't want a g8.

In the long haul, one is probably better off with the G11. But the G8 does better on the G11 tripod or other alternative mounting system.

Greg N

#13 WilRobinson

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Posted 02 February 2010 - 04:58 PM

Funny how the people that don't have a TMB 130 on a GM-8 say that it won't work and the people that do have a TMB 130 on a GM-8 say it will.

#14 hudson_yak

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Posted 02 February 2010 - 05:39 PM

Yes, always a wide range of opinion for topics such as this. "Working" means different things to different people, and then there are other factors, such as how steady your hands are with focusing, whether you use the scope while standing or while seated, and so forth.

I think it's probably true that in general the size of mount people are willing to pay for and carry around is not as good as it could/should be for the size of telescope they are willing to pay for and carry around but they just live with the combo anyway.

Ideally the OP can get a chance to try some similar setups before plunking down any money.

Mike

#15 gnowellsct

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Posted 02 February 2010 - 06:10 PM

Funny how the people that don't have a TMB 130 on a GM-8 say that it won't work and the people that do have a TMB 130 on a GM-8 say it will.


There are different generations of OEM tripod out there for the g8. This has led to differing views of its capabilities.

Greg N

#16 SteveC

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Posted 02 February 2010 - 06:25 PM

Funny how the people that don't have a TMB 130 on a GM-8 say that it won't work and the people that do have a TMB 130 on a GM-8 say it will.


That's the point of asking the question, to get different opinions. I've learned that the GM-8 might work with a better tripod than it ordinarily comes with.

#17 Robo-bob

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Posted 02 February 2010 - 06:39 PM

I had a TMB130 on a recent iteration of a GM8 until recently. I felt it was barely adequate for the 130 which is quite a heavy scope for it's aperture. Still, I really enjoyed the combination but frequently pined for a slightly more rigid mount. Using this OTA effectively on this mount requires getting things up a bit higher so you are not sitting in the dirt when viewing at zenith. My solutions was a 12" semi peir between the tripod and the mount. That way, the legs only had to be put up a couple inches and the mount was still reasonably sturdy.

The best part of this set up was that I could pick the whole thing up and carry it outside without too much trouble. This fact made it a great grab and go system.

hope this helps - Rob

#18 Mike Clemens

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Posted 04 February 2010 - 10:42 PM

I used a TMB130/6 on a GM8 and loved the combo.

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#19 SteveC

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Posted 04 February 2010 - 11:37 PM

Hi Mike,

Which tripod did you use?

#20 Mike Clemens

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Posted 04 February 2010 - 11:58 PM

GM8... the weak link, but fine for visual

#21 hudson_yak

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Posted 05 February 2010 - 10:34 AM

Yes, that looks like it would work pretty well, with the focuser knobs relatively close to the saddle. That is the big difference between the ED100 I used to use on mine and the TV-85 I use now. There wasn't much difference in weight between the two scopes, couple lbs maybe. Leverage was the issue.

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Mike

#22 mountain monk

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Posted 05 February 2010 - 03:20 PM

Thank you all for your comments. It sounds like the tripod is the weakest link. If you put the GM 8 in on a Berlebach UNI24 (say, or a UNI14) and restricted it to visual use---would that cut it? Would most of you be satisfied with that?

mm

#23 hudson_yak

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Posted 05 February 2010 - 04:26 PM

Compared to the Losmandy LW tripod, I found the UNI24 to feel a bit stiffer in twist (rotation about the azimuth). Perhaps a little faster damping time, though certainly not what I had been hoping and been led to understand I'd get with a wooden tripod. Deflection while working the focuser with my ED100 was also not significantly improved.

I view standing up so used my LW tripod at full extension and even added additional 6" length with some wood inserts in the lower legs. I used the UNI24 at the same height.

I now think it would have taken the Planet tripod model to provide a significant improvement in stiffness over the LW, at least if you use them with legs extended a good bit.

Mike

#24 SteveC

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Posted 05 February 2010 - 06:03 PM

Thank you all for your comments. It sounds like the tripod is the weakest link. If you put the GM 8 in on a Berlebach UNI24 (say, or a UNI14) and restricted it to visual use---would that cut it? Would most of you be satisfied with that?

mm


I'll think about it and get back to you. Don't order anything until you hear from me! ;)






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