I am trying to decide what lens should I use for eclipse and I am wondering if my 70-300 IS USM would be enough or should I get (rent) a lens with higher magnification. Since my solar filters are going to be only in a week, I wonder if somebody could share not cropped image ofwas wondering, how can I determine how big the sun would be if I shoot at 300mm on APS-C to help me decide? What about at other focal lengths?