Auto Focus sensitivity on the Canon 5D MK3   Leave a comment

I was getting that little nagging feeling in the back of my mind just recently that something might be amiss with my 5DMK3. In particular with the camera’s auto focus when on AI Servo.

I’d been using it to shoot a few sporting events and was noticing an unacceptable number of out of focus shots. I may have shot a series of 5 or 6 images on a continuous burst and on reviewing them afterwards found that at least 1 and sometimes 2 of them were out of focus. I’d search around to see if I could see the focus point and often it would be the background and on a few occasions a foreground object. I scratched my chin, twirled my moustache and contemplated what could be wrong.

In the end I put it down to my sloppy technique faced with the alternative that the legendary auto focus system on the MK3 – borrowed from the Canon 1DX – was faulty. Not something I wanted to admit to nor did I relish the prospect of having to send the camera away to Canon for rectification. So, off I went last weekend to shoot some more fast moving entities and … .. what!? The same issues again. Now I know by now that most of you reading this will have worked out what the problem was and be berating me for not seeing it myself but… hey, we all get a little blind spot from time to time.

Of course, eventually it dawned on me one evening last week whilst watching some repeat on TV. I snatched my camera up from its bag and pressing the back ‘AF-ON’ button to focus I panned across my living room and watched the focus point rapidly switch from object to object as it passed over them. What a poltroon! So, activating the Menu on the camera I flicked the joystick until I got to the AF menu and to the Tracking configuration and there it was – the sensitivity setting on my Case 2 (Continue to track subject ignoring possible obstacles) was set to its most sensitive. This effectively meant that whilst I was tracking a subject with my focus point any movement off that point – shifting from the racing Husky dog’s eye to it’s chest for example, or even worse, slipping the focus momentarily off its head to the woodland behind it, meant that my focus point jumped just quickly enough to cause me to get an out of focus shot as I tried to track back on to the dog’s head. Too sensitive. So I shifted the setting to the opposite end of the scale which meant the focus would delay shifting for much longer.

I’d used this sensitivity slider on my 7D previously and correctly set it for the kind of sports I shoot. I must have set the Mk3 up the same way when I got it (fairly recently) and been under the impression I’d set it to the same level. So, yesterday i set off for the Mellish Rugby Club again to give the new setting a run out just to make sure everything was working properly and that this was indeed the problem. The result? Every single shot in focus. Except for two, which were my fault as I’d slipped on the sodden waterlogged grass behind the goal posts and ended up on my arse.

I’m now a happy bunny again. 🙂  Here are some of yesterday’s pictures.


Early ball




Try run 02


Broken tackle




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