to know how to light scenes. The more you know about any aspect of film production the better, but if you don’t know about lighting a scene you can still direct. What I do is make notes on the look, feel, and mood I see in my head for each scene. I pass that along to the DP so we can discuss how to make it happen. I also like to suggest to the DP movies to rent with scenes I feel lighting wise are close to what I’m going after. Your DP is the master of light. He’ll deliver the lighting set ups you need.
The director needs to know how to run the camera. Not true. It’s very possible you will never touch the camera once during a shoot. I myself for the most part watch through a monitor. I do look through the camera after the DP has set the frame for the shot, but I rarely run it.
It’s easier to direct a low budget indie movie than a mainstream Hollywood