I love my 5DMk2, but when I use a TC with my 100-400 L, I don't like the slow or erratic AF response (pins are taped). Plus, there is a slight degradation of the image.


Byran lists the new Sigma zoom lens APO 50-500. A web search shows that it's gonna cost around $1600.


I can't afford Canon's 500 L. I want the reach of the 500, though. I've got wide angle lenses to cover the other end of the scale.


A 7D will make my 100-400 go out to 640 mm. The Sigma 50-500 will be 500 on my FF 5D (which is really the place I'd have this lens all the time, anyway).


With the prices nearly the same, it seems like a new body would be the better way to go.


So, what's your take?