I'm debating which flash to get for my Pentax K100D. I'm mainly considering between these two: Sigma EF-500 http://www.bhphotovideo.com/bnh/con...107&is=REG&addedTroughType=categoryNavigation vs. Pentax AF360-FGZ http://www.bhphotovideo.com/bnh/con...172&is=REG&addedTroughType=categoryNavigation First of all, will the Pentax flash be of higher quality? My instinct is yes, but I don't know from experience. Second, how useful is a swivel head? (which the Pentax doesn't have) I assume it is mostly for use when I'm shooting vertically, but still want to bounce off the ceiling. Which one would you get. (the Pentax is $45 more, after rebate) Why?