by Dave Mitsky
A complete 22° solar halo was visible from my front yard shortly after 1:00 p.m. EDT on May 14, 2013. I captured a portion of the halo using a Canon PowerShot SD980 IS digital camera set on automatic (ISO 80 at f/8).
http://www.atoptics.co.uk/halosim.htm
http://www.atoptics.co.uk/halo/circular.htm