AF fail

[gary]

Does anyone know why the Mk2 EF 1.4x extender paired with the 100-400mm Mk2 won't Auto Focus on the 50D but works fine with the 5D mk3. thanks

 

[Maximilian]

100-400mm Mk2 = max. F5.6 (widest aperture)
F5.6 x 1.4x Extender = F8.0 (approx.)

5DMkIII has AF with F8.0 (like 1DX has, too).
50D has AF only up to F5.6 lenses. ==> MF only.

Everything works as Canon has implemented.

 

[gary]

Thanks for that, Maximilian, another learning experience

 

[Mt Spokane Photography]

There are some tricks that will let it at least try to autofocus, it will probably work slowly.

http://photo.stackexchange.com/questions/27599/how-to-enable-canon-af-with-teleconverter

 

[sedwards]

if im not mistaken , AF will work in liveview at F8.

 

[Mt Spokane Photography]

if im not mistaken , AF will work in liveview at F8.

Yes, but using a long telephoto with TC and liveview can be extremely difficult unless on a sturdy tripod with a very still subject. If you are lucky, a bird might sit on a branch in one spot long enough for liveview on a 50D to focus. It will likely hunt for a while.