In my quest for good lenses to use for AF on the new 70d, I have picked up a few to test, and I have tested some that I use on the 5d3.
So far, these lenses are way too noisy for AF video (shotgun mic wouldn't even help):
Sigma 17-50 2.8 HSM VC (great lens otherwise - I shot with an external mic 2 ft away outdoors! and you could still hear it AF).
Tamron 17-50 2.8 - Didn't own it but heard the AF on Youtube - older screw drive lens that's pretty loud
Canon 50mm 1.4 - loud
The following are lenses that are pretty close to being acceptable that I've tried.
Canon 35mm F/2 IS - love the lens, but probably just a tad too loud. Still heard the lens with external mic. Just barely.
Sigma 30mm ART 1.4 - in a quiet room, no, but outdoors, probably ok. Way quieter than the 17-50.
Here's lenses that I feel confident are quiet enough for video AF use:
Obviously, the 18-55 and 18-135 STM Canon's
24mm F/2.8 IS Canon (not as quiet as STM, and it's a shade quieter than the 35mm). It's close.
Tamron 24-70 USD VC 2.8 - Actually pretty acceptable.
Canon 70-200 IS II 2.8 - Pretty darn quiet too
Let me know if there's interest and I can create a video with all the above lenses for you to hear, minus the Canon 50/1.4 and 35/2 IS (I no longer have them).
Thanks!
Shawn