by Dave Mitsky
Here's an afocal shot of Mercury that I took on the evening of 2010/4/14 using a Canon EOS Digital Rebel DSLR camera, a 2" 32mm University Optics Koenig-II, and the ASH 17" f/15 classical Cassegrain. Mercury was quite low in the western sky and the effects of atmospheric prismatic dispersion are clearly evident.