Hi Chris ,
Your 12 inch on a perfect night get 500x plus , but in reality thats not really possible . Stick to around the 150 - 200x .
To many variables . Seeing , turbulence , clouds , etc , etc.
I find on the planets and the moon , my 63mm Zeiss with its 840mm focal length and my 2x Celestron ultima barlow used with my 12.5mm Badder real orthoscopic eyepiece , that gives 133x is about perfect .
That combo shows a perfect image of jupiter , lots of deatail and not to bright .
I can easily top 200x plus, but the seeing wont allow that most nights , so 133x is nice .
Brian.