AF jittering problem

I was using a 750D today in full daylight and a Canon 17-55mm f/2.8 IS USM lens.

I noticed that on half pressing the shutter release the lens was jittering in and out and seemed unable to focus. I am using one shot AF mode and manual selection 1 point AF (the centre spot)

I know AF can be tricky in low light, but this was a sunny day and a static subject (a lake)

Anyone have any suggestions?

Ah. I didn't try that. I shall. Thanks

Even in full daylights, AF points still need contrast/lines to focus on. If you were aiming at a part that had low contrast the camera might not be able to find anything to focus on.

Maybe I should just use the 19 point automatic selection instead. Perhaps that's more idiot proof.

I never really know which AF mode to use

Digirame wrote:

Most of the time, I use 9 point autofocus selection in the center with my Canon T7i (800D) cameras. I have to be careful with that, to make sure that the autofocus is precisely where I want it, because it can mess things up, when the depth of field is shallow (like when using a telephoto lens). So, when I use it, I carefully note where it is being focused. Most of the time, it's OK doing it that way.

I think I just have the mode with the single spot in the middle. I put that on the object I want to focus on, then keep the shutter half pressed and recompose to get the shot i want.

I think with the 9 point mode, you have to manually select one of the points, right? How is that more efficient than just using the centre spot and recomposing?

(apologies for the rookie question!)