canon tc's

[steunited]

Is there a great deal of difference between the canon 1.4 mkii and the 1.4 mkiii in terms of IQ considering the price for a used mkii go for around £180 and a new mkiii is around £400.
i had the kenko pro 300 and regret selling it a few months back and it was ok but am tempted to try a canon version on my 100-400.

 

[modchild]

I've got a 2x MkIII converter that I use with my 70-200 f2.8L IS MkII and get some great results with it with regards to IQ. It still AF's at a decent speed too, I managed a few BIF with it the other week. I've not used the Canon 1.4x converter cause I've got a Kenko Pro300 DGX 1.4x (because it's compatible with more of the lenses I have) and it's such a good performer.

I've used the Kenko with a 100-400 L and the IQ was still very acceptable and it even retained AF on the 7D and 5D2 I had at the time even though they had a f5.6 rating whereas your 1D3 is an f8 rated body for AF. In very good light the Kenko gave a pretty good AF speed, but tracking wasn't great on my 5D2, and only started hunting a lot when the light faded. I'd really like to try the Kenko and 100-400 on my 5D3 with the uprated firmware which now AF's at f8 but I don't have the 100-400 any more.

 

[seriousrikk]

On your 100-400mm you will see very little difference using the II instead of the III