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silly question about counterweihgts and mounts


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Hi all

I am a complete novice but appreciate that the better the mount, the heavier the equipment that can be used / the more stable the viewing etc.

Is my logical thinking way off in wondering whether adding more counterweights would make a less stable mount, more stable? does it work like this or would more weight just create a mount more likely to break? I currently have a CG-4 which is the one I have in mind and use for a 120mm Celestron refractor but am also considering the purchase of a Vixen GP as a stronger mount for (eventually) a larger Newtonian.

Sorry if this is a stupid, and probably badly phrased question but I am sure you get my drift - no pun intended.

thanks for an guidance.

Shane

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hi

the problem with adding more counterweights is to be able to balance the scope.

i would think that adding forinstance lead pellets inside the mounts legs, would be a better solution, but heavy.

alfi

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  • 2 weeks later...

thanks a lot alfi

I think you are right although I am thinking now about making some wooden legs and salvaging the tripod parts like the hub etc

that way I can get it high enough for my own purposes (I am 6'4") and also a lot more sturdy / attractive.

yes, I'm a modifier by nature! from the looks of your reply and some of the other posters, I'll fit right in!

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There is some method in adding more weight to a mount, just not counter weights though. I have often seen suggested a bag of sand hung down from the center of the tripod, of filling the legs up with something suitably heavy. Extra weight in/on the tripod itself can only make it more stable and, hopefully, less prone to vibration.

The best set up I've ever used is a Tal mount and pier. Solid and weighs a ton!

Having said that, you don't really want to add weight if you've got to move the thing far!

Edited by TheThing
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Always best to use "dead" weight, ie non moving weight. Moving weight will add to the strain on your mount operation. Adding weight to your tripod is the best bet, you wont break it with anything you can lift. Good idea to make it removeable so you dont have to carry it along with the tripod and if possible use something useful like a 12v battery as already suggested.

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Extra weight in/on the tripod itself can only make it more stable and, hopefully, less prone to vibration.

Don't confuse the ability to prevent toppling with the ability to absorb vibration. Adding mass to the moving part - whether tube or counterweight - increases the mass which is vibrating & therefore reduces the steadiness of the image to see (or capture with a camera). You want to keep the thing light but consistent with mechanical rigidity. That's why carbon fibre composite tubes are often used on top end equipment.

Filling hollow tripod legs with sand can help reduce vibration, if it's the legs that are the weak link in the chain (and they often are). So can replacing metal legs (which "ring") with wood, especially ash, which is an excellent vibration damper. You might even be reducing the absolute rigidity but, if vibrations damp out much faster, the view will appear to be steadier.

The recommended maximum load is just that; if you have a long tube (refractor) you'll want to stay well within the limit, with a short tube (Mak or SCT) you may get away with loading up to the limit. If your site is windy, you'll need less weight on the mount. If you want to do long exposure imaging, cut the weight limit in half because you need the mount to perform better than it will when loaded to near max. You can probably overload a mount by several hundred percent before there is any danger of an actual mechanical failure (provided that the load is balanced reasonably accurately).

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Great stuff everyone - thanks so much for your kind suggestions. I reckon that I will be using a hybrid of some of them. Just off shortly to make a wooden tripod - I am quite handy anyway but my father in law is a joiner (!).

I also like the idea of the diver weights and will probably rig up a 'hanger" for one on each leg just below the spreader which will hopefully give the best of both worlds.

In terms of mount I have a Vixen GP and a Celestron CG-4. my scopes are a both celestron XLTs - I have the 120mm refractor (for which I am making the wooden tripod) and the 150mm refractor (which I bought as an OTA off this forum) and which I will use on the standard steel 1.75" tripod legs set low. I reckon the GP will be used as my normal mount when using one scope but if I invite a mate round I'll probably use the CG-4 with the reflector and the GP with the refractor. does this seem sensible?

I stress that taking images is a long way away for me - it's really a proper investment. I have a perfectly good 'camera' in my mind which records all the amazing things in the sky quite well enough for now 80)

Also, is there anyone near Stockport that would be willing to meet me and confirm I have got the hang of collimation? I have followed some online guides and think I am getting it right but there's nothing like an expert to check things over before you base your future assessments on a dodgy footing!

cheers again

Shane

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