Preparing for this week’s expected heavy rains and wind, I went to the roof of the observatory to clean out the rain gutters and check the downspouts. Chores done and with the dome open, I made another experiment at solar imaging through the big vintage Cooley Telescope. I found I could focus on the Sun (through a safe solar filter) and, with a Canon DSLR camera at the telescope’s prime focus, recorded a few one-shot images at ISO 400 and 1/500 second. The telescope is a 9-inch refractor with a focal length of 3,327mm. The results appear better than last time but show the apparent effect of atmospheric turbulence: that’s my story and I’m sticking with it! A few sunspots were visible and details of Sol’s roiling atmosphere show up. The photographic technique is the simplest we can use; more sophisticated processes are employed these days to achieve best results. Still, proof of concept is a good thing and getting the image focused is a critical step. I think next time we may try a dimmer subject.
Stephens Memorial Observatory 