The Late John LeBrun pictured
John LeBrun (a professional camera equipment salesman and diver) taught us a couple of points about photography he had learned from his service in the air force.
“When you focus on an object, the area that is actually in focus (also called depth of field) is 1/3 in front and 2/3 behind the point that you’ve focused on”.
You can use this knowledge to some advantage at times.
Generally we were all self-taught photographers. The most difficult part in the learning days was getting a good exposure, especially underwater. Most divers tended to over-expose pictures.
Today the camera’s are automatic in this respect but sometimes adjustments make a nice difference. Sunsets are better if the exposure is make darker, for example.