Focus problem - is this a fault in the G7 camera

Brisn5757 wrote:

Here is an example

https://youtu.be/PAakOpQ6G_I

Can someone see why the camera went out of focus?

Examples are always useful!

If you look close, there is zooming going on just before the camera loses the focus. I tend to avoid zooming while filming, mainly because it looks "unprofessional".

Another thing is that if there is a lot of shake, then it can be very difficult for the AF algorithm to keep the subject in focus (shaky video is also annoying to watch). The basic idea of contrast-detect auto-focus (CDAF) is that it measures the contrast (sharpness) in the user/camera-defined area(s)*. Then the camera adjusts focus back-and-forth, until the contrast is maximized. This is when the camera assumes that the focus is right.

When the screen is shaking, the contrast at the focus area(s) constantly goes up and down, making it really hard for the camera know if the area is in focus or not. Also, shake causes motion blur to individual frames, so even if they are perfectly in focus, the contrast can be low (and constantly changing).

The AE/AF lock button can be configured to temporarily lock the focus for situations when you suspect that the camera might lost the focus (without moving the AF/MF lever around that button). I prefer to have set the 'AE/AF lock button hold' ON. This way when I press the button once, it locks the exposure/focus until I press the button again.

P.S. If you record audio, then an external physically isolated microphone is recommended, as the internal microphone will record all the sounds when pressing the buttons. Alternatively, the touch screen can be used to change the setting silently.

*What focus method / areas / patterns do you use (left keypad button)? I gave my recommendations for this in earlier post.