MESSIER 42 MOSAIC
Celestron Fastar 8 at f/1.95, PixCel 237. This is a composite image created in Adobe Photoshop. It consists of six 120 second exposures (each a combination of eight 15 second images Track and Accumulate), using the AP900 with PEM correction engaged. Unguided at -17.25 degrees Celsius. This image set was shot in early February 1999, but I gave up attempting to create a mosaic with the support frames. There seemed no way to add them together and eliminate the seams and overexposure, due in part to the great dynamic range of the nebula complex. Then I hit upon the idea of merging the frames, then adding additional frame "cuts" of the nebulae complex north of the main nebula. I then independently adjusted the levels of these cuts, allowing me to balance the two nebular regions. I think this is similar to the burning and dodging techniques used in darkrooms of the past. The image took about five hours to complete, all while my wife was in labor!