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Balancing a CPC

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#1 dave beine

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Posted 15 June 2013 - 11:53 AM

I use a Celestron CPC (9.25) for visual observing on the stock alt-az mount. It is gaining weight ! I have just aquired a 2.4 lb eyepc. The heavy eyepc + the 2" diagonal weigh about 58 oz; I also use a 16 oz finder.


My local observing buddies are split 50/50 as to yes/no; I am leaning to no since the added weight on the front is just more weight to turn and lift.

(By the way, I do tend to travel all over the sky in a 90 minute period)

Should I add weights to lessen the stress on the motors?

Thanks for your input.

#2 Arizona-Ken


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Posted 15 June 2013 - 12:11 PM

I have a CPC1100 and have had the same questions over the years. This is what I found.

The CPC series does not have to be perfectly balanced. It can never be during an observing session, unless all your eyepieces are the same weight. I keep my eyepieces at a pound maximum, not easy to do now-a-days.

I have found that as a scope gets really out of balance it will not slew accurately. The slews will be close, but will slowly get worse as the session progresses. This is your scope's way of telling you it needs counterweights.

As you apparently move your scope around a lot, I would suggest that you just monitor your scope's accuracy. You'll know when it is time to add counterweights.

Arizona Ken

#3 Footbag


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Posted 15 June 2013 - 01:27 PM

I added counterweights to my CPC when I added a piggyback scope and rings.

Just for EP's it would be a waste of money IMO.

#4 Brian Risley

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Posted 15 June 2013 - 08:11 PM

On an 800, eyepiece weight, no issue (have 4k 8.8 and 14 uwa's I use), piggyback scope, yes. With the piggyback tracking became noticeably affected depending on position. They can handle a bit of imbalance, but if it gets too much, you will need counterweights. (I suspect binoviewing will need to be CW'd)

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