Useful astronomy links for reference I have included here . They cover a range of subjects from Planetariums to processing software and are all free   Field of View calculator based on camera , scope  combination     Planetarium    Astronomy images     Astronomy buy and sell      Canon camera control   Image processing        Free download image processing software    Night sky object suggestions based on location etc  Designed for Canon , gives Field of View with all camera / lens combination  Stacking and post processing software    A comprehensive list of all usefull astronomical imaging software . From image processing, Capturing ,EQMod and Planetary software. Free