Canon Extender III

[mark_farrell]

Hi, I'm looking at getting the 70-200 f/4 L IS lens, and am also musing over an extender, either a 1.4x or a 2x. My main reason for this route (both the f/4 and an extender) is weight - I'll mostly be hiking when using this kit, and living in Oz, there's usually plenty light so shouldn't often need the larger aperture offered with the f/2.8.

My questions about the extenders are:

1) How much quality loss is there?
2) Apart from the extra stop of light lost, does the 2x have any other flaws relative to the 1.4x?
3) Are the Mk IIIs worth the extra over the Mk IIs?
4) How well will the camera autofocus with effectively an f/8 lens?
5) How does the IS cope with being on an extender?

Cheers!

 

[Mike Jackson]

If you use a 2x extender on an f/4 lens most canon bodies won't AF. Only the 1 series will AF at f/8.

 

[mark_farrell]

That's worthwhile knowing! It's a 5D MkII

 

[markmullen]

I use a 1.4 exii on a 70-200 F4 IS and it is very difficult to see which shots were taken with the extender and which without, I end up looking through the exif data to see which were. AF isn't much slower, although I am using 1 series bodies which are known for their AF. IS doesn't seem to be affected at all.