Why does my footage become blurry underwater?

Hi there. Have a look at the video and you will understand what I mean.

I don't know if fog is instantly created on the lens or what is going on.

The big as fish I'm looking at in the video was clear as day for my eyes, and the footage is just horrible

https://youtu.be/frMhWsQH8x0

The bubbles from the regulator exhaust certainly don't help! Getting the camera away from the exhaust would be nice.

The blurriness is just out-of-focus, it's not fog or anything.

Doesn't that camera require a flat underwater lens protector rather than the dome you are using?

See manual pages 60 and 63.

"The lens protector is not for underwater use. Use the underwater lens protector."

it looks like you have autofocus set to C-AF (continuous) and the camera is hunting in and out of focus as you weren't close enough to the fish for it to lock.

A brief review of the manual shows you should use the underwater lens protector. The standard lens protector is a dome and this changes the optics - it means the the camera needs to focus on a virtual image a few cm in front of the dome, the minimum focus distance is 0.2m and the camera may be struggling to achieve focus underwater. I suspect they use a flat underwater protector for a reason, flat ports reduce field of view but you don't have the close focus problems. You also need to change the angle of view in the menu to "wide- underwater" and may want to set white balance to underwater auto.

Also agree about the exhaust bubbles, the camera may be trying to focus on them which could confuse the issue even once you have the UW protector installed.

There's is no setting in the camera for autofocus or similar options, but it's set to underwater mode.

I do have the square protector, but I didn't think it mattered which one I used because when I compare them it's the same result - allthough I only tested this on land.

So what you're saying is that the refraction of the light going into the camera is different on the two lenses, but only underwater? I had no idea that this would be reason why.

This was the first time I used it for diving and I was just trying out the headmount, and well, it mostly works, but the adjustment of the camera position is tricky when you can't see the screen. I'll try something else next time.

Thanks for your answers, I hope I get better results next time.

That's correct, the dome port only has issues when it's underwater, you noticed that it snaps straight into focus when you bring it above water. If you want to find out more google dome port optical theory, if you don't want to get into that it's purely because of the different refractive index of water and air. If you have air on both sides of the dome it has no impact.