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Old 03-09-2014, 01:26 PM
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5ash
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Balancing an imaging Newtonian?

I was thinking of getting a newtonian telescope for imaging , but thought about the 1+kilograms of camera etc hanging of the focuser and the ramifications that has on proper balancing. I then researched it on the web and found that to counterbalance the camera load on one side you have to place a balancing weight on the opposite side of the tube , at the mirror end. When weight isn't an issue I can see this as the answer. My question is are do all Newtonian users go to this trouble to balance their imaging scopes? I'm looking more at a RC scope with focal reducer as a compromise .
Philip
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Old 03-09-2014, 02:38 PM
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alocky (Andrew lockwood)
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I don't. I rotate the tube so that the camera is inline with the dec axis, on the inside. No problems so far.
Cheers,
Andrew.
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Old 03-09-2014, 02:43 PM
glend (Glen)
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First I've heard of any balance issues. I have a Canon 450D and Baader Coma Corrector on my focuser, with a guide scope mounted amidship and don't have any trouble with balance. I use a NEQ6Pro, and the scope is 8" Imaging Newt (f/5 @ 1000mm fl). The weight distribution usually sees it sitting in the middle of the dovetail. I did swap out the stock short dovetail bar for a long one so I could space the rings as far apart as practical. The guidescope and camera are mounted on another dovetail bar on the top of the rings, this helps stiffen up the whole structure.

I check the mount balance each time I setup, and adjust if necessary for neutral balance point in both axis. I have not had to use any additional weights anywhere, just the standard counterweights on the shaft.

However, if you had a much larger newt, like a 12" then I would imagine that the weight of the primary might start to impact the balance point, at least to the point where you might have to slide the tube in the rings.
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Old 03-09-2014, 02:55 PM
raymo
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I have the HEQ5 with an 8" f/5 Newt. I have done a mod so that I can
rotate the tube easily into a convenient position for viewing or imaging.
I have a DSLR, camera cooling box,[home made prototype], and electric focuser, hanging off the side, and I don't have any trouble achieving balance.
raymo
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Old 03-09-2014, 03:24 PM
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rustigsmed (Russell)
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Quote:
Originally Posted by alocky View Post
I don't. I rotate the tube so that the camera is inline with the dec axis, on the inside. No problems so far.
Cheers,
Andrew.
+1 I do the same. its fine if you are connected up to a laptop - otherwise will be difficult for you to access the buttons.

cheers
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Old 03-09-2014, 06:03 PM
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Thanks for the replies , I do remember having a 10" skywatcher on my neq6 a few years ago and finding that I had to orientate the focuser in a particular way to get that sweet balance point , that with the clutches on the mount open you can point the scope in any direction and it does not move. What worried me was with over 1 kilo of camera and OAG on the focuser I might have a problem . I looked on the net and found all sorts of answers involving counter weights on the opposite side of the tube.they said they'd calculated the moments about the optical axis to derive the value and position of the counterweights.
So the consensus of opinions is that the tube only need be rotated to achieve the "sweet" balance point.
Regards philip
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Old 03-09-2014, 06:37 PM
raymo
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I think that unless you are working at or near to your mount's capacity,
balance is less critical than is generally supposed. As long as I have a little imbalance to ensure good gear contact, my scope's tracking
ability doesn't change regardless of where I rotate the focuser/ camera
to. I am not talking about massive amounts of imbalance, of course.
raymo
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Old 03-09-2014, 08:37 PM
clive milne
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You do not need to use counterweights on the ota if you orient the focuser position like so:
http://m6.i.pbase.com/g9/21/44721/2/...6.mT3h84LE.jpg
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Old 03-09-2014, 10:50 PM
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Quote:
Originally Posted by clive milne View Post
You do not need to use counterweights on the ota if you orient the focuser position like so:
http://m6.i.pbase.com/g9/21/44721/2/...6.mT3h84LE.jpg
Thanks Clive , your picture answers my problem
Regards philip
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