I just wanted to add another observation regarding the DoF function.

In the aftermath of my initial posting, I went to check if I could render the scene with another camera without the DoF effect.

Turns out the DoF is turned on in every camera available.

Since the DoF checkbox in the render settings panel is unchecked in any case, DoF can't be turned off for this particular file.

I didn't checked if a new scene is also set to use DoF. If that's the case I will come back and put in another post.