whiplash3333 wrote:
Just got off the phone with Canon Tec. Support. Right from the horses mouth. The 1/4 extenders II & III's DO NOT WORK after 5.6 (Auto Focus). You Lose about 1 1/2 f/stops with II extender and III You lose about 2 f/stops with the 2x. With a app.of 4 you go to 8 with 2x. The higher the number the more you lose. On both models. I hope everyone can understand what I just said.
Thanks for calling Canon Tech for us. I have gotten so used to manual focusing my 100-400 w 2x III extender. It's become fun and challenging especially following birds. Getting ready to try some of the goodies in my 5d thanks for the info!