How can I take pictures with one eye open and one eye closed?

First of all, it is not necessarily good to take pictures with one eye closed. If you can keep your eyes open when taking pictures, and it doesn't affect the composition of your right eye, congratulations, you are superior to others.

My teacher used to take pictures with one eye closed, but later she changed to keep all her eyes open, so that she can observe what the viewfinder can't see with the other eye and pay attention to the relationship around her. This is even more important if you are a child photographer. You can observe the surrounding environment, safety factors, parents' position, emotions, etc., which is very conducive to taking pictures.

My eyes are wide open now, too.