Logical upgrade from a Canon L f/4 70-200

[Orange Peel]

I've always been very happy with my 70-200 lens but would like more reach. Would a 1.4x or 2x converter be the way forward or should I look at anther lens.

I mostly use it for motorsport?

[peppyuk]

1.4 should work, but you will get focus problems with the 2x.
I if you want more reach then I guess 100-400 is the next step if you stay with Canon, or look at some of the Sigma zooms.

[nigpd]

I think the answer from the motorsport boys will be to get the 100-400mm.

I have the 1.4 converter that gives me a bit more reach when needed but I dont do motorsport. I use it for birds when I cant get quite close enough.