Canon 100-400mm f4.5-5.6 L IS II Panning Question

[reheat module]

Well, I've just thoroughly cooked my swede trying to understand the functionality of the 3mode IS switch on this lens.
I'm borrowing this lens to do some Panning of motorbikes.
Mode1 appears to be for general shooting (but suggests best for static subjects)
Mode2 seems to indicate it reduces horizontally in vertical movement, and vertical in horizontal movement????
Mode3 operates at point of shutter release only.
A simple question: Panning with motorbikes as a subject, in AI Servo and high-speed cont drive, what is the best IS mode position 2 or 3?
It's a one-off opportunity and I'd like to try and minimise my failure rate.
Many thanks

 

[andrewc]

2 or leave it off

 

[Deleted member 26215]

Well, I've just thoroughly cooked my swede trying to understand the functionality of the 3mode IS switch on this lens.
I'm borrowing this lens to do some Panning of motorbikes.
Mode1 appears to be for general shooting (but suggests best for static subjects)
Mode2 seems to indicate it reduces horizontally in vertical movement, and vertical in horizontal movement????
Mode3 operates at point of shutter release only.
A simple question: Panning with motorbikes as a subject, in AI Servo and high-speed cont drive, what is the best IS mode position 2 or 3?
It's a one-off opportunity and I'd like to try and minimise my failure rate.
Many thanks

Personally I would turn IS off. The panning action will negate any vertical movement of the lens.