M13 in Hercules, Taken Oct 8, 2007 with 5-inch Astro-Physics apo refractor at f/6 with Canon 20Da camera at ISO 400 for stack of 2 x 12 minute exposures. NGC 6207 galaxy at top. Guided with Meade DSI/66mm guidescope and PHDGuide sofware.
The globular cluster Messier 13 (M13) in Hercules, with the small galaxy NGC 6207 above it. The very tiny galaxy IC 4617 is just visible between NGC 6207 and M13. M13 is generally considered the finest globular cluster in the northern half the sky (north of the celestial equator). This is a stack of just two images, each 6 minutes at ISO 800 with the Canon EOS Ra and Astro-Physics EDF 130mm f/6 apo refractor with the 6x7 field flattener. The images were the last two in the sequence of 10, and were the sharpest of the set. Earlier images were softer due to poorer seeing?
M13 with 130mm Astro-Physics apo at f/6 with no field flattener (slight camera tilt results in more coma at left of frame), for stack of 6 x 6 minute exposures at ISO 800 with Canon 7D (stock camera, not modified). Auto-guided with SG4. Worked perfectly. Slight rotation around guide star made it impossible for Photoshop to do an auto-align. Had to manually align.
