Dual mount bar in use

[Steve_Max127]

I am just about to buy a dual mount bar and trying to get my head around using it. The dual mount bar will leave my two scopes at 90 degrees to where the scope is normally. How will this effect polar alignment, and the goto operation of the mount?

It may be obvious when you know how but never having used both scopes side by side it has me baffled.

[blinky]

Dont worry, I had the same question when I bought one of these bars!

It all workds fine - you dont need to change anything.

[Cornelius Varley]

Using a dual bar mount with a goto mount is not a problem. The home postion for the mount remains the same, counterweight down telescopes facing NCP. The mount always assumes this at the start of the alignment, so as long as you start in this position it doesn't matter if the dovetail slot on the mount is now 90 degrees away from it's normal single telescope position.

Peter

[Psychobilly]

You'l also be able to see through the polarscope in this "home" position... just watch your head on the back of the scopes when you get up....

Peter...

[Merlin66]

It's a no brainer... works 100%

[James]

When you have a telescope set up normally in the home position the saddle grove on the mount runs north-south as does the telescope. When a dual mount bar goes on you move the saddle 90 degrees one way so the grove effectively now point east-west. But.... when you put your scopes on they'll no longer be pointing the same way as the saddle grove, instead they'll be point 90 degrees the other way i.e. back in a northerly direction.

When you start the scope up it doesn't think, oh wait a minute I'm pointing 90 degrees to the west now, it just assumes that it's in the normal park position pointing north. When you choose your first star to align to it directs the scope to move the correct amount in RA and Dec to get from looking north to that object. As far as the mount goes it will in fact be wrong as it started in the wrong place but here's the important bit... the scope was pointing the right way to start with so it will end up pointing at the object; the amount of movement needed to get the mount from north to the object is the same as the amount of movement to get the scope from pointing north to the object.

Well done if you've made it this far and are still awake - I've probably worded that pretty poorly . Peter's spot on about the polar aligning. When you put a dual bar on you only move the sadlle of the mount, not the mount itself so the polar scope will still be pointing north but the scope and bar will be sticking out ready for your head to bang into them...

James

[Steve_Max127]

Thanks guys I knew it had to work just could not see how, the new dual mount will arrive next week so I'm sure I'll wonder what all the fuss was about.

Thank you one and all.

[ollypenrice]

Yes, the key point is just that the encoders are not callibrated in any way until you tell the scope, 'This is the home position.'

Olly