Bored again ...
I'm not taking the bait - but I'm looking forward to knowing the answer - thanks for doing this.
#1 is the best, both #2 & #3 have "issues", #3 comes in 2nd and #2 the worst.
Thanks Jambsi, I like the Pentax 300 f.4.0 myself. It will be wonderful on a Canon 60Da for diffuse nebulae and other faint objects.
Free your mind, and your camera will follow...