EF 100-400mm f/4.5-5.6L IS WITH a 1.4x Canon EF 1.4x II????

Does the Canon Zoom Telephoto EF 100-400mm f/4.5-5.6L IS works perfectly with the Canon EF 1.4x II Extender???? how about the auto focus still works as fast or not??
HELP!!
MS

You will loose some AF speed on 1-series, but on all non-1 series bodies the 1-4L IS will not autofocus.

AF is a product of LIGHT. the more light that goes thru the lens the faster the AF is. So then you add a TC, you lose light and thus, AF speed or ability altogether.

My 100-400 will not autofocus with my 1.4x II extender. I taped the pins after researching how and it will autofocus but is very slow and not very accurate. I have become quite accustomed to manually focusing the lens with very good results. My 70-200 2.8 IS will autofocus fast and accurate with the 1.4x II attached.