Re: wide angle lenses for dancing
 

I'd like a decent wide angle, but not a fish eye; great effect for some photos, but how often do you see it in video. The Olympus 9-18 is on my list, but has its limitations. Still for outdoors its ideal. Theres the 7-14, but no options for nd filters to be attached so you're either suffering poor resolution from diffraction or adjust shutter to stop motion effect. Neither appeals to me.

Re: wide angle lenses for dancing
 

I think it"s time to get a a7s with a with a 16-35mm f4.0 lens :) The 9-18mm olympus lens is a great one, very sharp across the frame, but it's quite slow. I think I just will need to continue using the 12mm f2.0 lens, it's too much of an investment for those limited time I might need a lens like that 8mm f1.8, can't think of any other part of the day I might use it unless for the dancing part. The 7-14mm f2.8 Olympus looks like a better investment.