Canon EOS 80D Manual (en)

When a lens mounted with Power zoom adapter PZ-E1 is attached to a 
supported camera, you can use power zooming in the [Remote Live 
View window].
Select the [Live View] tab and click the [PZ] button.
The [Power Zoom Control] window appears.
Select the mode from the [Variable speed] tab or 
[Constant speed] tab.
Variable speed mode: Zoom at changeable speeds.
Constant speed mode: Zoom at a constant speed.
Variable speed mode is selected by default.
Power Zoom Operation
Variable speed mode
Constant speed mode
Use power zooming.
Variable speed mode
Move the zoom lever toward [W] to zoom to wide-angle.
Move the zoom lever toward [T] to zoom to telephoto.
Changing zoom speed levels:
You can change speeds with the speed level switch.
Setting this to [SLOW] provides a slow zoom, suitable for movie 
Setting this to [FAST] provides a faster zoom than [SLOW].
Varying the zoom speed during zooming:
You can adjust the zoom speed with the zoom lever by the amount 
of its movement. Moving the lever slightly left or right provides a 
slow zooming. The more you move the lever to right or left side, 
the more the zoom speed increases.
Zoom lever
Speed level switch