Originally posted by Ishpuini I actually compared my DA*50-135/2.8 to my Sigma EX70-200/2.8, which is generally considered a fast AFfing telezoom. Indeed the Sigma travels in slightly over half the time from nearest distance to infinity. However, that time takes it from 1,8m to infinity, whereas the DA*50-135 starts at 1m. The 1,8m mark on the DA*50-135 is half way its travel, so when measuring the time it takes to travel from 1,8m to infinity it is actually faster than the Sigma!!
I think we should be comparing to similar lenses, rather than to primes or standard zooms... If you do that the DA*50-135 isn't that slow at all. Except when it hunts, then it does take more time, but that's solely related to its starting at 1m already...
Just another way of looking at things...
Wim
That's interesting and true, the focus is more than fast enough if you go from 2,5m to infinity and most of the full travel time is taken to go from 1m to 2,5m.
Maybe that's why Canon incorporates a limiter that goes from 2,5m to infinity (AFAIK) to cut the AF time on their 70-200f2.8...
I did a lot of tracking shots yesterday (my 4 years old coming towards me on its bike in bright sunlight) and, while AF-C doesn't struggle to keep up with the action, the shots end up being slightly back focused if one uses f2.8. Of course, stopping down the lens to f8 gets you almost all shots in acceptable focus but then blurring the background is difficult.
Predictive AF should be better implemented in future Pentax cameras, especially if higher frame rates are introduced.
Actually, a higher frame rate should mean faster mirror/shutter mechanism and lead to better "predictive" AF since it will cut the lag between focus and picture taking and should automatically reduce the amount of backfocusing.