Nice image, but this is NOT the Encke gap. That's an artifact due to overprocessing.
You can see the Encke gap here (image by Damian Peach):
http://www.jodrellbank.manchester.ac.uk/astronomy/nightsky/saturndp.jpg
or on images from HST and Cassini-Huygens. It's actually very close to the outer boundary of the A ring.
Newtonian telescopes are convenient for planetary observing and photo since they have a small obstruction, no chromatic aberration.
You prove it by your very nice image, fine details and well-balanced colors (despite the artifact).
Nicolas.