Mount Wilson: MY NIGHT WITH THE 100-INCH SCOPE p. 22 DIY: MAKE YOUR OWN COLLIMATOR p. 66 Test Your Scope: HOW SHARP CAN YOU SEE? p. 30 T H E E S S E N T I A L G U I D E TO A S T R O N O M Y The Impending Flood of Big Data p. 14 Planet Imaging: Video Stacking Made Easy p. 68 SEPTEMBER 2016 STRONG PROSPECTS for Weak Lensing Stroll Through the Summer Triangle p. 54 Test Report: iOptron's Nightscape Camera Mount p. 58 p. 34