We were saddened to hear that our good friend Paul Boltwood passed away on September 25. Paul's passion was engaging in seemingly ridiculously ambitious projects, and then achieving spectacular results. He had not just dogged determination but also an absolutely incredible attention to detail. I liked to say that Paul could see the forest for the trees, but first he would get on a first-name basis with every tree. His results were always nothing short of astounding. Paul Boltwood in his observatory. In 1989 he decided to build an observatory with a CCD camera. At the time CCDs were in their infancy, so he decided to build his own. But this was no cookbook-style camera. It had a vacuum chamber, 4-stage TEC, and cooling delta-T of nearly 100C. He operated the camera year-round at a fixed -72C. Paul's camera including vacuum chamber, electronics, filter wheel, shutter wheel, and focal reducer assembly... all custom-built by Paul. A close-up of the chamber and electronics assembly, showing the vacuum fitting. He designed the vacuum chamber so well that it only required pumping down about once a year. Paul didn't just build the equipment, he put them to good use. He was very interested in scientific observations, and worked with professional astronomers on long-term monitoring of blazars OJ287 and 3C66A. He made incredible high-resolution image sequences of Comet Hyakutake, which were featured in the Comet Odyssey video. He observed an occultation of a star by Saturn's rings and with incredibly detailed results. He also won an imaging contest at Sky & Telescope magazine, where the goal was to image the faintest star with amateur equipment. Just one frame from Paul's Hyakutake video sequence. In 1995 Paul was awarded the Chant Medal of the Royal Astronomical Society of Canada, and in 2000 the Astronomical Society of the Pacific's Amateur Achievement Award. Paul's 1999 winning image for Sky & Telescope's Deep Field Challenge. With a total exposure of 31.6 hours on a 7" refractor, he achieved magnitude 24.1 (later improved to 24.5 with better processing) from a backyard site (19 mag/sq arcsec). Paul has many connections to us here at Diffraction Limited. The Cyanogen Imaging branding we use for our software products originated as a company, Cyanogen Productions, which was incorporated by Peter Ceravolo and myself to make and distribute the aforementioned Comet Odyssey video. MaxIm DL incorporates some of his software, namely the FITS file interface module (MaxIm DL predates FITSIO by many years). And, perhaps most significantly, Paul is the inventor of the eponymous Boltwood Cloud Sensor, which is used at observatories all over the world. Paul was a good friend and will be dearly missed.