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Canadian Telescopes Duo T-Mount first light

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#1 jason_milani

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Posted 22 March 2012 - 07:30 AM

I purchased a Canadian Telescopes Duo T-mount from Woodland Hills recently (same as the Skywatcher Skytee II) and finally got it out last night for some testing. I purchased the head only and mounted it on a Meade LXD 75 tripod (early version with the 1.5" legs).
The mount is unique in that you can actually aim the second, top mounted scope independently in altitude and azimuth. You do need a counterweight for the scope on top or it throws the whole thing off balance which is why i wouldn't go over a 15 lbs. or so payload on that side.
With a C-6 on the fixed end and an Orion 120ED on the adjustable side (and 10 lb. counterweight) it balances out nicely. The slow motion controls are smooth, although i did make a slight modification to the altitude slo-mo control as there was too much play in the worm gear when i received it.
Quite stable with the pictured load, it's rated for 15 Kilos per side but that seems overly optimistic - i wouldn't go over 20 lbs. per side, especially with this tripod.
Overall, i am impressed thus far. It's a great mount to do comparison testing between different telescopes. :)

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#2 Mark9473

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Posted 22 March 2012 - 08:02 AM

So you feel the fact that the two scopes don't point at the same target, is a feature rather than a drawback?

#3 jason_milani

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Posted 22 March 2012 - 08:19 AM

They DO point at the same target if you align them that way. That's the best feature of the mount - no worrying about a dual setup not being orthogonal between scopes.

BTW - moderator, i accidently posted this in the refractor forum - meant to post it in the mount forum.

#4 Mark9473

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Posted 22 March 2012 - 09:05 AM

no worrying about a dual setup not being orthogonal between scopes.

Could you elaborate what you mean with this?

#5 Dave Ponder

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Posted 22 March 2012 - 09:24 AM

When you get a minute, could you measure the length from the floor to the mounting clamp with the legs fully extended? Curious how tall, it is...thanks!

#6 Cotts

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Posted 22 March 2012 - 09:29 AM

In a dual mount (or a side-by-side) which only has rigidly mounted dovetails (and you do want them to be rigid...) you're asking an awful lot to expect that the two telescopes mounted thereon will point at precisely the same point in the sky to small arcminute tolerances.
Pretty much impossible, actually.

Thus the need for micro-adjustment of one of the scopes.

Dave

#7 Mark9473

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Posted 22 March 2012 - 10:02 AM

I understand what you're saying Dave but I'm not sure what you mean.
Will this mount allow two scopes to be aligned precisely on the same target or not?
Or is this like two independent mounts that happen to share a tripod?

#8 jason_milani

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Posted 22 March 2012 - 10:10 AM

The mount allows two scopes to be aimed precisely at the same target but they can also be aimed at different targets as well.

#9 Cotts

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Posted 22 March 2012 - 02:46 PM

You will be able to aim the two scopes so that they are both centered on the same object at the highest power you have. Probably better than 30 arc-second accuracy.

You would first center the non-adjustable telescope on Polaris using the mount's AZ and ALT motions. Get it as precisely centered as you can, using a cross-hair eyepiece and a barlow to get the highest magnification. Then lock the mount to prevent movement. Then move the cross-hair eyepiece and Barlow to the adjustable scope and center Polaris again but using the fine adjustments instead of moving the mount itself.

Hope this helps.....

Dave

#10 Mark9473

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Posted 22 March 2012 - 03:02 PM

Crystal clear, Dave! :waytogo:

#11 Sean Puett

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Posted 22 March 2012 - 03:11 PM

I just ordered this mount (plus the wooden tripod) yesterday. I live in Washington so delivery should be pretty quick. The wooden tripod looks pretty stout so i went with it. What counterweight are you using? The Canadian telescope site says skywatcher cw work but who sells those or what other brand is compatible? Thanks.

#12 jason_milani

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Posted 23 March 2012 - 06:44 AM

I'm using a Meade LXD 10 lb. counterweight. Any CG5 style should work although i tried a Celestron CG5 11 lb. weight and it sometimes bumps into the mount when aiming toward the horizon since that weight is wider.

#13 jason_milani

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Posted 23 March 2012 - 07:41 AM

Moderator, please move this thread to the mount forum. Thank you.

#14 hottr6

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Posted 23 March 2012 - 02:13 PM

In a dual mount (or a side-by-side) which only has rigidly mounted dovetails (and you do want them to be rigid...) you're asking an awful lot to expect that the two telescopes mounted thereon will point at precisely the same point in the sky to small arcminute tolerances.
Pretty much impossible, actually.

Thus the need for micro-adjustment of one of the scopes.

Dave

I use one of Ken Dauzat's adjustable side-by-side saddles on my CG5 GEM. It maintains a pointing accuracy between the two OTAs of less than 5' through many observing sessions. In truth, I have never had to re-align it after the first session.

When I look at these dual-scope alt-az setups, I don't see the ability to parallelize the OTAs. Does this mean that dual-scope alt-az's cannot be parallelized, or is there some hidden machinery in their castings?

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#15 Sean Puett

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Posted 23 March 2012 - 03:06 PM

It is supposed to be easy with this mount. The guy who told me about it said it takes like 30 seconds. It will probably take me longer at first.

#16 hottr6

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Posted 23 March 2012 - 05:06 PM

I can see how the Canadian Telescopes mount does it.... I'd like to know how it is done on other alt-az mounts, such as the Stellarvue MG2, ES Twilight II, Skywatcher HDAZ, Meade LX80, KSON KM2, etc. It seems to me that the Canadian Telescopes alt-az is the only alt-az that can parallelize side-by-side OTAs.

#17 7331Peg

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Posted 24 March 2012 - 01:20 AM

The Universal Astronomics Double Star is an alt-az that can also be "parallelized" -- the left side of the mount adjusts to match the right side. Not quite as quick an operation as the Sky-T/Canadian mount, but it works very well.


John :refractor:






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