500mm or 600mm +TC? will AF still work?

[merlyn9]

I'm planning on leasing (renting) either a 500 or 600 mm IS lens
for a trip to Alaska, and some Eagle shoots along the mississippi river.

My question is, will both these lenes still autofocus with the 1.4 TC?
I'm currious, only since my 100-400L IS will NOT AF with the TC... & those
eagles move too fast, AND I don't want to loose too much light & details

thanks;


---michael

[quickben]

It would depend on which body you're using. If it didn't AF with the 100-400L, I'm guessing you're using either a 300D or 10D, and as the other lenses you want to use have the same, if not smaller, max apertures as 100-400L I'd say they won't AF.

Gary.

[RichardtheSane]

Since both those lenses are a max aperture of F4 which is greater than your 100-400L then putting the t/c on will still allow autofocus to work

The convertor will change the max aperture to F5.6 which will allow AF on all EOS bodies

It is only above F5.6 that the DSLR's (other than 1 series) loose AF (except on 3rd party lenses)

[merlyn9]

I could easily live with the f/5.6 on my EOS 10D.
It just keeps making me sick when I think I have a great shot, only to discover the f/8.0
killed the shot! (not Enough light... or too much movement)

Now I guess I just need to battle the demons on which I want to pay for...

[CyberDyneSystems]

Richard has it correct,. in fact there is no Canon Digital SLR that you would not get AF with either of those lenses and a 1.4X

Please check the -=EOS STICKY=- thread at the top of the page for a link to a host of additional t-con info that may be of use to you.

[merlyn9]

Please check the -=EOS STICKY=- thread at the top of the page for a link to a host of additional t-con info that may be of use to you.

CDS... Thanks! didn't realize that info was up there?
I'm going to assume the Tamron 1.4 TC I have will be fine...
While out on an extended project in Sacramento, the guy at the photo shop said I would be fine with one given the expense of Canon's at the time (I was tight on $$$)
It's been good for me under right conditions with the 100-400... just that AF thing....

thanks;

---michael