I could not find any comparison between these two lenses on the internet. Anybody on the forum who has experience with both lenses? In view of the price difference one would expect a significant difference in optical performance. Of course the CN-E 18-80mm has typical cine lens characteristics (parfocal, better manual focussing) which the EF-S 18-135mm has not.

the EFS lens is fine for some things but it has issues. For one, if you snap zoom you see it hunt focus, which no other EF lens I own does. It's far from parfocal, much less parfocal than L series glass. It's a weird thing to watch in the viewfinder. Also, it is very touchy on focus. Small movements of the focus ring make it swing like a focus pendulum on drugs!

Of course, the CN-E lens suffers from none of these issues and is really a nice setup for the price. It's a slow lens, probably it's achilles heel... but then again, so is the EFS 18-135.

There have been 3 versions of Canon's EF-S 18-135mm lens, and they behave pretty differently in terms of autofocus response. From oldest to newest (I hope I have this right!):

18-135mm USM
18-135mm STM
18-135mm nanoUSM

The latest version, the nanoUSM is by far my most outstanding autofocus experience on 70D, 80D, and C100. AF is incredibly fast, and (almost) never hunts! It tracks pretty darn well too...

Scott, I'm not using snap zooms... so I wouldn't know about AF performance there. Which version have you been using?