| Any extender will degrade image quality to some degree. I have the Canon 1.4x which I use on my 70-200 f/2.8 IS L and I find the results quite acceptable. I believe it works better with L primes such as the 300 f/2.8. I have used the 2x (not mine) and the results were somewhat disappointing, and that seems to be the consensus among users. So, if you can manage the 70-200 f/4 with a 1.4x then do it - the results will be quite OK. But not the 2x. Of course the f/4 will become f/5.6 with the 1.4x. If you use a 2x on the 70-200 f/4 then its maximum aperture will become f/8 and you will lose AF unless you have a 1 series body.
If you do get the 70-200 then you will be pleased with it. Sigmas, Tamrons and others would have a hard time matching it.
Cheers, Bob |