Handbook for
5 minutes) and press the ‘Autoguide next image’ but ton. The autoguider window will reappear and, after a few seconds, you should see error values appearing in the text windows at the top. The guide star will be fairly close to the green cross, although not necessarily accurately centred, and you should see the power/ guide LED on the rear of the camera brighten and change colour with each correction.
10)If the star begins to drift away from the cross, despite the corrections being made, the chances are that the N/S and/or E/W directions are set wrongly. Judge which axis is incorrectly set by observing the direction of the drift and then stop the exposure by pressing ‘Esc’. Open the guider control panel and check the appropriate swap box(es). After this operation, you will probably need to find the guide star again by taking a guider image and reselecting the star, as before. Now return to the main camera menu and try the ‘Autoguide next image’ button again.
11)Once guiding is taking place without problems, the main exposure can be allowed to finish and, if all is well, you should see an image with tiny circular stars.
If the stars are not circular, you may need to alter the guiding parameters, or investigate the rigidity and drive performance of your mount. A lot of information can be deduced by watching the behaviour of the guide star in the guider frame. If it is continually moving between two locations, either side of the green cross, then the RA or Dec pixels per second value is set too low. The higher these values are set, the gentler the guiding becomes. Too low a value will cause an over- aggressive correction to be made and result in oscillation of the star position between two points.
Another source of guiding errors can be a too accurately balanced telescope mount! Good balance can result in the telescope mount ‘bouncing’ between the gear teeth as corrections are made. A simple fix is to add a weight of about 0.5kg (1 pound) on the eastern end of the declination axis, so that there is always some pressure acting against the gear teeth.
Getting a good result from an autoguider will often entail a lot of detective work to eliminate the sources of gear error, telescope flexure, mirror shift etc., but the final result is well worth the effort!
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Camera maintenance:
Very little maintenance is needed to keep the
Removing Dust:
1)Dust can be deposited on either the optical window (not a big problem to cure), or on the CCD faceplate (difficult to eliminate entirely). When small particles collect on the window they may not be noticed at all on deep sky (small F ratio) images, as they
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