Canon 70-300L with 1.4 teleconverter

[Jack Breakfast]

Greetings!
Certainly the Canon teleconverters will not work with the 70-300L. I've tried my Kenko Pro and the image quality is quite good but the AF becomes problematic (lots of hunting) even in bright light. I wonder if any owners of the 70-300L have had success with this teleconverter or any other third party teleconverters? I'd certainly appreciate any experiential information...
Many thanks!

[Doug Brown]

I wonder if putting an extension tube in between camera and lens would work?

[Jack Breakfast]

Interesting thought, Doug, and thanks...does anyone have experience with such?

[John Chardine]

No but I could try it out. I would think you would lose infinity focus but I'll test it all out and get back.

[John Chardine]

You lose infinity focus but with the 12mm extension tube you can focus to about 40' which is a useful range for smaller subjects.