Celestron Compustar Bedienerhandbuch PDF herunterladen (Seite 36)

direction, then there may be some slack that has to be taken up whenever the next correction is in

–Dec before the drive engages the gear teeth in the opposite direction. If guiding in Dec does not

appear adequate, you may need to add backlash compensation. It may take some experimentation

to find the correct setting. If the setting is too low, guiding corrections will be delayed while the

backlash is being taken up. If the setting is too high, over correction will occur. You can

determine whether a backlash correction might be needed by grasping the telescope with your

hand and trying to wiggle it up and down along the declination axis. If you feel movement or

hear clicking, then backlash exists and may be an issue. Try tightening the Dec axis lock to stop

any movement first. That is the better solution to the problem.

Lastly, there is usually a menu item to select whether both the RA and Dec axes are to be

corrected simultaneously as opposed to sequentially (See legend of Figure 17). This is an option

because not all mounts can make simultaneous corrections in both axes. Sequential corrections

can result in poor tracking. If the guide star moves off target diagonally, then the autoguider has

to first correct the error in one axis, say X, and then correct the remaining error in Y. This not

only takes longer, but also allows a new error in X to creep in while the previous Y error is being

corrected. Fortunately, the Compustar mount is capable of simultaneous corrections in both axes,

so do be sure to enable this feature if your autoguiding software offers it.

Balancing the Compustar

Astrophotography will burden the Compustar mount and drive components with considerable

extra weight in the form of imaging camera, guiding camera, cables, guide telescope or off-axis

guider, and the weight will certainly throw the Compustar out of balance. Rebalancing the

Compustar is one of the most important steps for achieving accurate tracking results with an

autoguider. It has been said that almost all tracking problems can be traced to improper balance.

Regardless of how strong the drive motors of the Compustar may be or how good the

autoguiding software is, tracking will be more accurate if the Compustar is properly balanced.

Proper balance will also result in less wear on the Compustar‟s drive components, which may be

difficult if not impossible to replace. Therefore, balancing the Compustar for autoguiding will

pay off in more ways than one.

Balancing the Compustar should be done with all of the imaging equipment attached in the

configuration to be used for imaging. A counterweight bar assembly with counterweights, or

other telescope balancing system, is essential. The Compustar 11 and Compustar 14 come with

them as standard equipment. As you check the balance of the telescope, you will be releasing the

clamp on the Dec axis, which is almost always locked on the Compustar. Be extremely careful

that the out of balance telescope does not swing out of control resulting in components striking

you, the mount, or other objects in the vicinity of the telescope when the lock is released.

Padding the telescope drive base with pillows is a wise precaution during balancing.

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Celestron Compustar Bedienerhandbuch Seite 36