Celestron Compustar Manual de Instruções descarregar pdf (Página 37)

Fork mounted telescopes should be balanced first with the optical tube assembly aimed in the

vertical direction, then in the horizontal direction. Begin by slewing the telescope so that it is

centered on the meridian. Then, slew the telescope straight up at the zenith. While carefully

keeping one hand on the telescope, so it doesn‟t swing out of control, slowly release the lock on

the Dec axis and note which way the telescope wants to swing. If the telescope is top heavy, due

to the finderscope, guide telescope or other components on the top side, then the front end will

swing north. Add weight to the counterweight bar on the bottom side of the telescope (or remove

it from the top side) as needed until this tendency is counteracted. If the telescope is bottom

heavy, then the front end will swing south. Add weight to the top side (or remove it from the

bottom side) until this tendency is counteracted. Where you put the weight along the length of a

counterweight bar is not important at this point. That will be addressed during the upcoming

horizontal balancing. It only matters that you add it to (or remove it from) the correct side. As

you approach vertical balance, the telescope may no longer swing on its own. You will have to

give it a gentle nudge in each direction to see if further counterbalancing is needed.

Once the telescope is balanced vertically, relock the Dec axis and slew the telescope southward

until the optical tube is horizontal. While gently holding onto the telescope with one hand,

slowly release the lock on the Dec axis and see which way the front end of the telescope wants to

swing. If the front end swings down, then slide the weights on the counterweight bar toward the

rear of the telescope until this tendency is counteracted. This can be done using weights on either

the top or the bottom, or both. If the front end swings up, slide weight forward until this tendency

is counteracted. Again, as you approach horizontal balance, you may need to gently nudge the

telescope each way to see if further adjustment is needed. Once you have completed this task,

the telescope is dynamically balanced along all axes. It is a good idea to mark the positions of the

counterweights on the counterweight bar assemblies with colored tape for future reference. You

may also want to repeat this process with the telescope configured for visual use and mark those

positions with a different color of tape. That way, you can quickly rebalance the telescope for

visual and photographic use.

So, what just happened? The telescope has 3 axes, the RA axis, the Dec axis and a longitudinal

axis (not to be confused with the RA axis), which runs right down the center of the optical tube.

The telescope rotates around the RA and Dec axes, but not the longitudinal axis. All three axes

intersect at a point half way between the left and right fork arm swivels. Any object rotates

around its center of gravity. The mount and drive motors of the Compustar are designed to turn

the telescope around a center of gravity located at the intersection of the three axes. It is with the

center of gravity at that point that the drive motors will have their optimal lever arms (force

times radius of rotation) which, in turn, will require the least amount of torque to rotate the

telescope around either axis. Moving the center of gravity away from this point by adding

equipment produces a different lever arm for the drive motors, which in turn requires more

torque to move the telescope along any axis. This puts more wear and tear on the drive

components and, in some cases, the torque required may be beyond what the drive motors can

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Celestron Compustar Manual de Instruções Página 37