New Canon 70-200 2.8 IS II focus problem

msowsun wrote in post #16722794
Mine also behaves just like your with the lens cap on. I wouldn't worry about it. Especially since you have a 2 year warranty.

Thanks! Good to know this behaviour is normal.

MakisM1 wrote in post #16722796
The lens has some built-in logic which assumes 'normal' user behavior.

Unknowingly, you seem to have violated a whole bunch of assumptions of what Canon considers 'normal' (IS on, distance switch positioned appropriately, shooting with the cap off).

Contrary to what you 'believe', I believe that a $2400 lens should be designed to provide the best performance under 'real world' circumstances... with the cap off!

In my book this means keeping one of the best implemented IS applications 'on' AND sharing with the lens the secret that my subject is more than 3 meters away. Always with the cap off .

Did I mention that I prefer taking pictures with the cap OFF?

Now, I'd suggest, if I may, that you take this marvelous lens and go out in the real world, in the first available opportunity and shoot anything that moves or doesn't. Give it a chance to astound you!

Enjoy!

Haha I know no one likes the fact I had the lens cap on, but I didn't have the time (had to go to bed early) to take a video of the lens focusing on an actual subject (or trying to, at least). The lens with the cap on and then off and focusing on a low-contrast target exhibited the same behaviour, thus I decided to just make a video of the lens with the cap on (saves time getting the other tripod out etc) to demonstrate this behaviour.

I know of the newer TC's slowing down AF to improve accuracy, but I did not know Canon had implemented this idea into their lens(es). Now I know (and others in the future), thanks!

Out of curiosity I tried mine, it is the same as yours if not slower. Even in a dimly lit room with the lens cap removed, aimed at a plain wall, it was just as slow. As soon as contrast and/or light increased the focus speed returned to normal.

Cinch wrote in post #16723068
Out of curiosity I tried mine, it is the same as yours if not slower. Even in a dimly lit room with the lens cap removed, aimed at a plain wall, it was just as slow. As soon as contrast and/or light increased the focus speed returned to normal.

Thanks very much! I just got home and finally got to test the AF for real outside (2pm here with quite a few clouds in the sky). It performed brilliantly as expected (incredibly easy to do BIF compared to the 150-500 I had). AI Servo performance thus far seems considerably better than the 150-500 (not unexpected) and quite a bit better than the 135 f2 and 70-200 f4. This was all expected, but I just didn't know the behaviour in low light/on low contrast subjects was normal. Now I do, thanks everyone!