A:AnswerThis lens is not compatible with Canon extenders. People have reported good results with a Kenko extender, it's slimmer profile and recessed glass make it compatible. Using a Canon extender can damage the rear element of this lens.
A:AnswerI am fairly certain that it WILL work. I have rented this lenses cousin, the 100-400 L series on a T7i and it worked fabulously. Also, a number of reviews reference the results on APS-C lenses.
One specific review:
https://youtu.be/-7QkqSdenyI
