how do I focus

I am hs student new to astrophotography and recently I bought a SAC-IV imager and laptop to get me started. Last night, I was trying to get a quick image of the moon through prime focus and all I saw saw a large white glob on my screen. I turned the focus knob on my etx 90 back and forth and still the image failed to focus. I tried focusing earlier in the day on some pine trees in my neighborhood and was able to focus. I don't see what am I doing wrong. These forums are the only place I can turn to because nobody I know is into this hobby.

Hi Dasahu -
Hey, there are lots of people focusing these critters! Right now we are in the middle of developing focusers for the QuickCams and SACs to make it easier. One important place to go for help is the Quick Cam Users Astronomy group on Yahoo. Do search for QCUIAG at Yahoo and join this group. You can also follow this link to get to their archives: http://groups.yahoo.com/group/QCUIAG

There are lots of SAC users out there to help.
Right offhand, it sounds to me like you do have too little or too much backfocus distance and will either need to add an extension, or shorten up the way you are attaching the SAC.

Clear Skies!
Richard