Celestron CPC Deluxe 925 HD Computerized Telescope CPC Deluxe HD Manual - Page 17

>> Scope Setup Features Setup Time-Site - Allows the user to customize the CPC display by changing time and location parameters (such as time zone and daylight savings). Anti-backlash - All mechanical gears have a certain amount of backlash or play between the gears. This play is evident by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are pressed (especially when changing directions). The CPC's anti-backlash feature allows the user to compensate for backlash by inputting a value which quickly rewinds the motors just enough to eliminate the play between gears. The amount of compensation needed depends on the slewing rate selected; the slower the slewing rate the longer it will take for the star to appear to move in the eyepiece. There are two values for each axis, positive and negative. Positive is the amount of compensation applied when you press the button, in order to get the gears moving quickly without a long pause. Negative is the amount of compensation applied when you release the button, winding the motors back in the other direction to resume tracking. You will need to experiment with different values (from 0-99); a value between 20 and 50 is usually best for most visual observing, whereas a higher value may be necessary for photographic guiding. Positive backlash compensation is applied when the mount changes its direction of movement from backwards to forwards. Similarly, negative backlash compensation is applied when the mount changes its direction of movement from forwards to backwards. When tracking is enabled, the mount will be moving in one or both axes in either the positive or negative direction, so backlash compensation will always be applied when a direction button is released and the direction moved is opposite to the direction of travel. To set the anti-backlash value, scroll down to the anti-backlash option and press ENTER. While viewing an object in the eyepiece, observe the responsiveness of each of the four arrow buttons. Note which directions you see a pause in the star movement after the button has been pressed. Working one axis at a time, adjust the backlash settings high enough to cause immediate movement without resulting in a pronounced jump when pressing or releasing the button. Now, enter the same values for both positive and negative directions. If you notice a jump when releasing the button, but setting the values lower results in a pause when pressing the button, go with the higher value for positive, but use a lower value for negative. CPC will remember these values and use them each time it is turned on until they are changed. Slew Limits - Sets the limits in altitude that the telescope can slew without displaying a warning message. By default the slew limits are set to 0º to 90º and will only display a warning message if an object is below the horizon. However, the slew limits can be customized depending on your needs. For example, if you have certain photographic accessories attached to your telescope preventing it from pointing straight-up, you can set the maximum altitude limit to read 80º, thus preventing the telescope from pointing to any objects that are greater than 80º in altitude without warning. Slew limits are applied relative to the base of the mount not the actual horizon. So when setting the slew limits when using the telescope on an equatorial wedge, remember that a minimum slew limit of 0° would prevent the telescope from slewing down past the celestial equator not the horizon. To set the slew limit so that the telescope will slew to the horizon while on a wedge, you must set the minimum slew limit to equal your latitude minus 90°. Filter Limits - When an alignment is complete, the CPC automatically knows which celestial objects are above the horizon. As a result, when scrolling through the database lists (or selecting the Tour function), the CPC hand control will display only those objects that are known to be above the horizon when you are observing. You can customize the object database by selecting altitude limits that are appropriate for your location and situation. For example, if you are observing from a mountainous location where the horizon is partially obscured, you can set your minimum altitude limit to read +20º. This will make sure that the hand control only displays objects that are higher in altitude than 20º. If you manually enter an object that is below the horizon using the numeric keypad, the hand control will display a warning message before slewing to the object. If you want to explore the entire object database, set the maximum altitude limit to 90º and the minimum limit to -90º. This will display every object in the database lists regardless of whether it is visible in the sky from your location. Direction Buttons - The direction a star moves in the eyepiece varies depending on the accessories being used. This can create confusion when >> www.celestron.com 15