Since I were once worried myself about the Canon EF 85mm f1.2L II USM AF speed and I hate reading charts and numbers, (they do not really tell me how a lens performs in the real world) I have finally found the time to do a quick and empirical autofocus speed test, using the lens coupled with a Canon EOS 5D Mark II body. This quick animated gif may help people making up their minds and fork out the hard earned $ once and for all.
The Canon EF 85mm f1.2L II USM AF speed is indeed slower than “regular” Canon L Ultrasonic lenses, but fast enough for the average user and even faster than I actually thought… really! Considering that the autofocus on the Canon EOS 5D Mark II it’s quite old and slow ( the camera shoots at only 3.9 frames per second) the quick test showed and confirmed that you can be assured you can achieve decent AF results, I would be very interested in seeing a similar test done with a Canon body with a much faster autofocus and fps like the 1DM3 or even with the new Canon 7D since its newly re-designed autofocus . The images were shots wide open at 1.2 by the way, so you know they have been shot at the shallowest DOF possibile. The SUV is approximately moving at 45 MPH and I used the center AF which is its only cross point. The animated Gif is slowed down a bit so you can see the focus is dead on.
If you are shooting portraits with the Canon EOS 5D Mark II and the Canon EF 85mm f1.2L II USM
or with the Canon EF 50mm f/1.2 L USM I would strongly suggest you order and install the Canon Eg-S super precision focusing screen which only takes 2 minutes to install!
Please see my other post about it here, with details from Chuck Westfall.