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c8 repair – balancing in dec June 10, 2009

Posted by aquillam in Astronomy, telescope maintanance.
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This post is one in a series about C8 repair and maintenance.  You should see the introduction and disclaimers before trying anything here.

If you can’t get the dec lock to hold, i may be that you need to balance the telescope in dec.  To determine if you need to balance the ‘scope, first put it on the mount and load it up as you would for a typical observing session. Point the ‘scope so the tube is roughly level. Put your hand under the mirror cell so you can catch it before any equipment can be damaged.  Then release the dec lock.  If the ‘scope is balanced, it won’t move.  If it moves, but not much or very slowly, you’re probably ok.  But it it swings down like it might as well not be on a mount, you’ll need to balance it.

Start by simply putting a dew shield on the front.  That is generally all it takes for our telescopes.  The only thing it doesn’t work for is the H-alpha filter. SInce we seldom image through it, we just live with an unbalanced ‘scope.  Students unfamiliar with using telescopes casue far more problems  than the balance problem (my favorite are the ones who use the dec fine motion control as a focus.)

If the dew shield isn’t enough, you’re going to need an accessory, which we don’t have, so I can’t offer and pictures or instructions on installing them.  However I do have a little advice.

Some tubes have a mountng hole on bottom in front to simply screw on a counterweight (espeicially if the original owner ordered the counterweights with the telescope).  Otherwise you will have to pick a system and an attachment method. I like the dovetail bars since they are very easy to adjust, so if you take off the camera you just slide the weight back to re-balance. Just remember, you really want something that can use the pre-existing holes, or you want to find someone who really knows what they’re doing. If you have to drill into the OTA, you can really make a big mess of things.

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