The Canon CN-E 18-80mm T4.4 COMPACT-SERVO Cinema Zoom Lens is the only option that I am aware of for a pro lens with a power servo zoom and aperature ring. Expensive at $4,600. I went with the Sigma DG 24-105mm f/4 HSM DG OS Aspherical Lens For Canon. Picked one up on eBay for under $500. Though it has no power zoom, the manual zoom has a nice feel to it, and with practice you can pull off a fairly smooth zoom.