My mount for the Forfax

[ecoles]

Hi,

I am a new member here. Just bought a used (looks like new) Forfax 140mm f12. I set it on my Orion Atlas and will be doing some mods on the Atlas to stiffen it as much as possible. the mods include purchase of a tripod spreader and battery tray from Deep Space Products, an Orion 8.4" pier extension, and addition of PVC wraps at the height of the upper spreader.

All that should be done next week. But I can see that no matter how rigid the tripod is and how I lower the center of gravity, the distance the scope extends out from the dovetail saddle along with its weight, gives it a lot of leverage and angular torque. So any force on the the OTA, especially at the ends, will cause unwanted movement of the saddle. It’s just a very long a lever arm. It doesn't take much, I have tested it myself.

So what else can I do here? I read some posts on building a Hargreave Strut. Anyone have an opinion about this idea? I can't be the only one who have faced this issue. I am completely open to more ideas on how to steady the Forfax on the Atlas.

Your opinions and suggestions are appreciated in advance.

Eric Coles

[jamesling1000]

Hi Eric Coles....

Welcome to ISTARSCOPECLUB......

Looks like you need to upgrade your mount....

i tried very hard on my losmandy G11 , to temporary use it for my 8" ISTAR F8.8.....Is 6Ft long if you add the focuser ....
Luckily mine does not come with the dew shield.....
Otherwise it will be almost 7Ft long.....

But surprisingly G11 heavy duty tripod, is able to dampen the vibration.....
but the g11 mount head cannot take the swivel....of the long tube.....and this affects the goto accuracy......

Regards

James Ling

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[rgm]

Congratulations on your purchase. I have a 127 f12 R30. So, my scope is shorter and lighter. I also have a Tak FS78 mounted piggy-back. This might bring my total weight higher than yours.

I bought a Losmandy G11. I was one of those observers that thought all my money should go into the telescope and eyepieces, and the mount was secondary. But with a long focal length refractor, I had to change my thinking.

The G11 works well, but I would not want to put much more weight on it. It is rated at 60 pounds, but my "rule of thumb" is to go about 75% max, which is 45 pounds, even for just visual.

I bought mine second hand, and it looks and acts as though it is brand new. The previous onwer used it very little, and only for photo with a small scope.

My 2 cents worth opinion - you may need a bigger mount.

[Watcher3]

A Hargreaves strut is worth a try IMO. Costs very little to implement, so why not? other than a permanent or semi-permanent pier, it is the most likely to make a difference with your available mount head.