Shopper : I have a EF 100-400mm zoom lens. Will this extender work with my lens/automatic?David B : Yes! I have a friend that has the same lens and he uses it in auto! Love it too BTW!KAARE J : The extender is compatible with L-series lenses, according to canon specs, see canon website for further help.
Hope this will be helpful.GREGORY L : I also own the 100-400 and enjoy using the wide range of focal lengths in its relatively light and compact package. The downside is that it is a relatively slow lens: f5.6 at 400mm. That is, of course the trade off, fast glass is also b-i-g and heavy (and expensive).
The relative slowness of the 100-400 is very pertinent to your question. The 1.4 extender III(which I also own) reduces the speed of a lens by 1 f stop. So the at the maximum focal length, the 400mm f5.6 becomes a 560mm f8.0. This reduction in f stop (light gathering capacity) has two negative consequences:
1. The ability of the lens to stop the action of the subject and reduce motion blur of the camera is reduced by half at any given iso AND
2. (probably more significantly) most canon camera bodies will not auto-focus an f 8.0 lens. The 1D Mark IV will; but even the newly released 1D X would not until a recent firmware update. I believe those are the only bodies that will auto-focus a 100-400 with a 1.4 tele-extender. I know the none of the rebels and even the 7d will not. I don’t know about the 1D S.
(All the camera bodies will still auto-expose correctly.)
Bummer! It seems that nothing in photography is simple or inexpensive. But this is not just some marketing ploy. Try manually focusing an f8.0 lens. It's really tough to detect image sharpness when the image is so dark. It's difficult for the camera body too.
Gregory LightOtterANDREW R : Lens Compatibility Chart:
EF 135mm f/2L USM - AF Possible -
EF 180mm f/3.5L Macro USM - AF Possible - The autofocusing range is from 2.6 feet/0.8m to infinity.
EF 200mm f/2.8L II USM - AF Possible -
EF 200mm f/2L IS USM - AF Possible -
EF 300mm f/2.8L IS USM - AF Possible -
EF 300mm f/4L IS USM - AF Possible -
EF 400mm f/2.8L IS USM - AF Possible -
EF 400mm f/4 DO IS USM - AF Possible -
EF 400mm f/5.6L USM - AF Not Possible - With the EOS-1Ds Mark III, EOS-1Ds Mark II, EOS-1D Mark III, EOS-1D Mark II, EOS-1Ds, EOS-1D, EOS-1v and EOS-3, AF is possible with the center focusing point only
EF 500mm f/4L IS USM - AF Possible -
EF 600mm f/4L IS USM - AF Possible -
EF 800mm f/5.6L IS USM - AF Not Possible - With the EOS-1Ds Mark II, EOS-1Ds, EOS-1D Mark II N, EOS-1D Mark II, EOS-1D, EOS-1v, EOS 1v HS and EOS-3, AF is possible with the center focusing point only
EF 1200mm f/5.6L USM - AF Not Possible -
EF 70-200mm f/2.8L IS USM - AF Possible - If the lens is attached to an EOS camera, having multiple focusing points and an Extender is attached to the lens, only the center focusing point will be useable for AF.
EF 70-200mm f/2.8L USM - AF Possible -
EF 70-200mm f/4L IS USM / USM - AF Possible -
EF 100-400mm f/4.5-5.6L IS USM - AF Not Possible - With the EOS-1Ds Mark III, EOS-1Ds Mark II, EOS-1D Mark III, EOS-1D Mark II, EOS-1Ds, EOS-1D, EOS-1v and EOS-3, AF is possible with the center focusing point only. The Image Stabilizer does not operate with the following cameras: EOS650, 630, 620, 600, RT, 700, 750, 850, EOS-1, A2, A2E, 10s, ELAN, Rebel, Rebel S, Rebel II and RebelSII.
