For optimal resolution from your scope, capture with the focal ratio around 5x the pixel size of your camera. So for a 290MM with a pixel size of 2.9 microns, the optimal f/num is around f/15 (see maths below). Since the native resolution of your OTA is f/5.3, aim for a 3x Barlow. or add an extension tube to the end of your 2x to increase the magnification. You might find you are close enough with the 2x as is. You can determine the actual focal length of your system using the equation below (from
here).
http://www.wilmslowastro.com/softwar.../formula28.png
On the CN website, someone recently posted a series of theoretical images for Jupiter and Saturn based upon the aperture size of your OTA - aperture rules for planetary
https://www.cloudynights.com/topic/7...or-comparison/
Andrew