EF 2X II converter

[stevekwiz]

I am new with Canon and need some help. I just bought a EF 2X II Converter, and it doesn't fit my Canon Zoom Normal-Telephoto EF 55-200mm f/4.5-5.6 USM Autofocus Lens, although the lens ITSELF is compatible with my Digital Rebel. I am at a loss as to why. ???

I believe that when I get a 400mm f/4.5-5.6L EF IS Lens that I can then use the converter and the lens on my Rebel. Is this true? One informed response would be great. :)

[CoolToolGuy]

The Canon teleconverters only work on certain lenses. Go here:
http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=220457&is=USA
and then click on the compatibility chart link. It will tell you which lenses are compatible, and how the autofocus is affected.

Hope this helps.

[KennyG]

Steve, go here - http://www.usa.canon.com/eflenses/lineup/supertelephoto/index.html and click on the extender, then you can see which lenses it works with. Remember, you can only have AF with an F2.8 lens and the 300D (Rebel) when using the x2.0 converter, as you lose 2 stops (ie: an F2.8 becomes an F5.6).

[optical]

Is the effect on the autofocus with converter, and the restriction to f2.8 lens, related only to 300D? Does it apply to 10D as well? Why does losing two stops affect the autofocus?

[Guillermo Freige]

You only can use AF with f/5.6 or faster lenses, in all Canon bodies except the 1 series (1V, 1D, 1Ds and MkII) and the EOS 3, in which you can keep AF at f/8 (in selected central AF points). As you loose 2 stops with the 2x TC, an f/4 lens becomes an f/8 one, so you loose AF except in the 1's. With a f/5.6 lens you loose AF in all Canon bodies (because it becames an f/11 lens)