May be you should rent first,see if you like it,

来源: 于 2013-10-31 09:56:52 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

try 500mm plus 1.4 extender,
or get a 7DII when it come out. 7D (or 7DII) with your 100-400 is a very powerful combination, light weight, affordable. With a 1.6 factor, it is a 640mm lens.