There's a joke on film sets: Why don't more Directors of Photography smoke? Because it takes 3 hours to light.

Typically the director chooses one or more angles for viewing the action of a scene, and then the production designer makes sure that whatever appears within the frame (wallpaper, props, furniture) looks right. Then the Director of Photography's, or DP's, job begins.

The basics of lighting involve setting up areas of light and shadow, of the kind you know if you enjoy black-and-white films. But from there, building a consistent color balance for a scene is an enormous amount of work. There are multiple different sorts of lights (incandescent, flourescent, LED, HMI), each with different color temperatures (often switched in and out within the same fitting), which are in turn modified with varying thicknesses of colored gel and which have to match the diegetic light sources - ie those which will appear on screen as part of the 'story world'. Sunlight is blue. So's moonlight, but not as blue - if it's too blue then it looks like a blue light instead of a white moon. Interior lamps have their own color temperature, which usually tilts orange. Then you have to deal with multiple lights; typically there's a key light illuminating the subject, a back light which helps to isolate the subject from the background (so the actors don't look like they have a tree growing out of their head or something - longer lenses flatten perspective and make it hard to differentiate foreground and background at narrow apertures) and a diffused fill light to balance these more intense point sources and obscure their artificiality, without losing the selective quality of the illumination. Each of these has to be color-balanced separately. Complex scenes sometimes require 6 or seven light sources. If you're shooting interior scenes and it's not essential to look out the window, it's often preferable to just black out all the windows or shoot at night, and employ artificial lights instead of the sun.

Here's an example of what it takes to make a scene look 'natural': https://plus.google.com/photos/109568505224923852682/albums/... What you can't see here is that the lower halves of the windows are covered with multiple sheets of neutral-density filter gets, gut to size (whereas the unfiltered upper parts of the window are just a glow of overexposure). that's several hours of work before it's even worth turning the camera on.

Shooting outside in sunlight should be simpler, right? Nope - you need reflectors (White? Gold? Silver? it depends), flags to take light off the hot spots, large silks for diffusion (which require extensive rigging to hold what is essentially a small parachute and prevent it flapping in the breeze), and people able to reliably adjust everything during the shot if the camera or the subject is moving. Also, the motion of the earth around the sub means that the position of everything needs to be tweaked about every 15 minutes as you do more takes and shoot things from different angles, all of which have to look completely consistent later on even if the source footage was shot hours apart. Also the color of the sun changes depending on the time of day.

Lighting for film is a massive headache most of the time* which is why you just don't see certain clothing combinations on film. A dress like this is enough to make an industry veteran cry.

* unless it's mild and overcast. Moderate cloud cover basically doubles productivity for daylight photography.