i am thinking of getting this lens for wildlife, mostly birds. i intend to use it on walks rather than sitting around in bird hides. i am currently using the nikon 70-300vr and d7000. i know that an extra 100mm is not that much but i already own the sigma 1.4 tc (works rather well with my sigma 150mm macro lens).
i was wondering if it is worth the expense of getting the 120-400 os, and if the 1.4tc will be useful with it. has anyone compared this sigma with the 70-300vr?
some sample images taken with the sigma would be nice to see.