Not a Canon extender, no, Canon "fixed" that. It does with the Kenko Pro range. Alas not had chance to compare with the 100-400 as mine is alas a rubbish copy. Others however on this forum have good copies so I think that I'm in a minority.
Why not get the Canon Extender 1.4x II or 2x III?
The 70-300 L does not accept an extender.
@OP - You're 200mm on the 50D gave you effective 320mm, with 1.4x converter then it gave you 448mm. If you need that sort of reach, then is it not more of a compare the 100-400mm with the 400mm f/5.6 and keep you're existing 70-200?
I Think criza meant an 1.4 extender to the 70-200f4. Which would actually make the fov similar to an 50d without extender...
« Last Edit: April 18, 2012, 05:04:00 PM by Zo0m »
Nikon D800, Nikkor 35 AF-S DX f1.8G, Sigma 85 f1.4 EX DG HSM, Sigma 150 f2.8 EX DG OS MACRO, Tokina 11-16 AT-X PRO f2.8 DX, Nikkor 28-300 f3.5-5.6G ED VR, Nikon SpeedLight SB-910
5D Mark 2, 550D, 12-24, 17-40L, 24-105L, 70-200 2.8L IS II, 50, 85, 550EX