People are often surprised when I show up on set looking like I just stepped off a construction site. While I admit my clothing is not the traditional "dress for success" attire that most people would expect, there is actually a purpose to it.
In the days before the traditional "talkies", directors and DP's would wear business suits -- and they would sweat. Today, filmmaking is all about finishing the project as quickly and neatly as possible. So directors, at least the ones who know what they're doing, are constantly on their hands and knees, carrying gear on their shoulders, and running all around set. This sort of labor doesn't go well with a nice suit from H.M. Cole.
So, when I'm on set, I'm usually wearing the following:
They're durable and allow me to get on the ground without hurting my knees. I try to make sure they have plenty of pockets too. My jeans on set are generally a bit looser so that I can move around in them more easily (i.e. no skinny jeans).
2. Black T-Shirt
I wear a black or grey t-shirt when it's hot out for one simple reason -- it doesn't reflect light. Especially if I'm working outdoors, I don't want to wear something that reflects light in to the shot since that could totally ruin it. If it's cold out, I'll wear a grey or black coat with lots of pockets.
Pockets are actually very important since we tend to carry a lot of stuff around with us on set. Tape, markers, iPhones, cables, it all finds its way into my pocket at some point so to stay efficient I keep plenty of pockets handy.
I prefer a baseball cap although any hat that covers your eyes will do fine since that's the primary goal. This is especially helpful when shooting outdoors.
4. Comfortable shoes
This is probably the most important piece. I'm not a fancy director that rides in on my director's chair. I move around on set A LOT. I need to be able to move between the camera and the actors and back again if needed. I remember when we did a shoot at UGA for THE UGA VAULT we were moving around Sanford Stadium more than most players do in a single game. Without comfortable shoes, that could've been a real mess.
So that's my uniform in a nutshell.
Please don't be offended when I show up to your set looking like that. Know that on set we're going for function not form (at least if we're behind the camera).
By the way, I'm well aware that Christopher Nolan wears a business suit when he's on set, but even he admits this is because it's what he's used to and he doesn't have to think about what he's going to wear when he gets up in the morning. And since he's Christopher Nolan, he can pretty much wear whatever he wants.