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Living with the Tandem rig.

ollypenrice

By ollypenrice
in Imaging - Discussion

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ollypenrice

ollypenrice

Posted
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I briefly described this rig in an earlier post when it was newly assembled but there is often a difference between how a setup ought to work and how it does work. I'm happy to say that this just works. You really do walk out, fire everything up, align, focus (two scopes) and hit to 'Expose' buttons. And off it goes. It's an absolute Godsend and is far more suitable for my situation than an ultra fast single astrograph which would need collimating, cajoling and probably regularly dismantling and cleaning as well. It has the simplicity of a refractor and the speed of a fast astrograph. SInce both scopes were second hand the total cost is comparable with a new premium ultra fast instrument (though you need two cameras.) One half belongs to Tom O'Donoghue so that cut the cost a bit as well!  :grin:

Last week we took a couple of deep images with around 20 hours apiece. Each image took a couple of nights. Everybody's happy!

I wonder, two ED80/Atik 460s on an NEQ6. What rig could you put together for the same price that could beat it? Buy an OSC and a mono for a fixed Ha filter and you don't need LRGB filters or a wheel...

Olly

Tandem-L.jpg

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nmoushon

nmoushon

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That is a beautiful setup you have there. Glad to hear its running smoothly for you. Quick question. I noticed that you have the back Tak solidly mounted and moveable while the forward Tak has the adjustable saddle? So you are adjusting one scope to match the other? At least thats how I'm seeing it from the picture.

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ollypenrice

ollypenrice

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You're right. One is fixed and the other is aligned to it on an excellent Cassady T GAD device like this...

CASSADY%20TILT-L.jpg

One of the possible areas of difficulty concerned the stability of this component. It works perfectly and holds the position of the scope reliably. If you want one I'd grabit while you can because Robin Cassady has retired...  Yves, eagle eyed as ever, spotted one for us second hand. We had previously tried a different make which didn't work. Smaller scopes would be OK in guide rings but these are both beefy and very short.

Olly

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nmoushon

nmoushon

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I have not seen one of those before. (Probably because they guy making them has retired) Thats a pretty cool little device. So I assume it move in all axii (X,Y,Z)? Z axis would be tilting over that central pivet point at those silver screws? Assuming thats what it is.

I've always thought of trying a dual rig and the rings never really set well with me. This on the other hand looks very robust. I must either get lucky second hand or might try my hand at making one.

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ollypenrice

ollypenrice

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I have not seen one of those before. (Probably because they guy making them has retired) Thats a pretty cool little device. So I assume it move in all axii (X,Y,Z)? Z axis would be tilting over that central pivet point at those silver screws? Assuming thats what it is.

I've always thought of trying a dual rig and the rings never really set well with me. This on the other hand looks very robust. I must either get lucky second hand or might try my hand at making one.

It only moves in x and y. To rotate the cameras you have the Tak rotators on the scopes. The tilt motion is nicely done, though. The top and bottom plates just pivot like a see-saw on two large ballbearings which sit in conical recesses. This is better than using a roller as a pivot because a high point near the middle of a roller would cause the top plate to rock. This rocking motion was the problem with the first type we tried. I think Robin Cassady has the right idea. It was a bit sad spending all that cash on it (600 euros second hand, inc side by side plate and the other saddle) because after spending no more than five minutes getting the scope aligned it no longer needs to do anything!

Olly

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ollypenrice

ollypenrice

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It looks fantastic Olly. What's that blue stuff in the background? it sets off the blue bands on the taks a treat.

It's a backdrop I bought from the local amateur dramatics society. Clouds are bad for publicity but I put a couple of harmless fluffy thermic ones on to appeal to the hang gliding fraternity... 

:grin: lly

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nucleardwarf

nucleardwarf

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I briefly described this rig in an earlier post when it was newly assembled but there is often a difference between how a setup ought to work and how it does work. I'm happy to say that this just works. You really do walk out, fire everything up, align, focus (two scopes) and hit to 'Expose' buttons. And off it goes. It's an absolute Godsend and is far more suitable for my situation than an ultra fast single astrograph which would need collimating, cajoling and probably regularly dismantling and cleaning as well. It has the simplicity of a refractor and the speed of a fast astrograph. SInce both scopes were second hand the total cost is comparable with a new premium ultra fast instrument (though you need two cameras.) One half belongs to Tom O'Donoghue so that cut the cost a bit as well!  :grin:

Last week we took a couple of deep images with around 20 hours apiece. Each image took a couple of nights. Everybody's happy!

I wonder, two ED80/Atik 460s on an NEQ6. What rig could you put together for the same price that could beat it? Buy an OSC and a mono for a fixed Ha filter and you don't need LRGB filters or a wheel...

Olly

Tandem-L.jpg

You really shouldn't be allowed to display that equipment in here, my wallet run upstairs and hid in the back bedroom crying.

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AlexB67

AlexB67

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I realise that this may seem impossible, but it looks even better in person - especially when you see the just how quickly it captures raw data :D.

I thought you would been married to and sleeping in that 20 inch Dob by now overnight. :grin:  

Sounds like you are having a good time and glad you got some clear skies while there :smiley:

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Naemeth

Naemeth

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I thought you would been married to and sleeping in that 20 inch Dob by now overnight. :grin:  

Sounds like you are having a good time and glad you got some clear skies while there :smiley:

I'm back in the UK now (came back today) - hence the clear skies - typical  :rolleyes:. 

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