Bob, I had this lens a few years ago,and sold it about 3 months after I bought it. not a very good lens IMO, it's soft


wide open at 500mm, bokeh is only so so. maybe it's just my copy. or maybe I got spoiled by the L lenses. if you really want this lens, I would try that one first before you buy it.


I know you really want something longer, will you consider a EF 500mm non IS version or if it's still too expensive, maybe waiting for the 500mm 5.6 is a better choice, but who knows. like I said anything longer than 420mm is not cheap in the Canon line.


one more thing, have you ever tried the "tape the pins" trick? maybe you should try it on your 100-400mm with your 7D.


good luck!