I’m using the NexGuide autoguider and the star appears bloated as I go from locking on the star to perform auto calibration. What's wrong?

You need to optimize your focusing technique. Focusing should be done in the Preview mode, which NexGuide is in when it's first powered on.

 

First, set the zoom level at least to level 2 so the star will appear larger.  The highest zoom level is 4 and it will make the star appear largest.  Focus at a high level of zoom before locking on a star, adjusting focus until the star appears smallest.  Also monitor the BRI reading.  It should increase as you close in on best focus.  While focusing, keep the BRI reading below 100 by using the "–" (reduce exposure time) button. This avoids saturating the CCD’s pixels and overexposing the image and will also help to achieve a better focus.

Also bear in mind that the CCD imaging chip used in the NexGuide has slightly rectangular pixels.  Consequently, stars may not look perfectly round at the highest zoom levels.

After focusing, lock on the star.  NexGuide will automatically switch the zoom level to 4. With this technique, your guide star's image should appear much smaller than before as you proceed into actual autoguiding.

 

Updated 12/27/13