Cinema School: Lesson 2 – Exposure and Lighting

The biggest mistake I come across with indie cinema productions is an over reliance on the low light ability of a given camera. It’s great to have a camera that can shoot decent images in low light, but the less light a scene has the more likely noise will be produced in the background of the image.

What is noise?

Have you ever seen a poorly lit video with grainy, randomly moving particles in the dark areas of the image?  Perhaps the particles were even during all the best lit portions of the image as well. The particles you are seeing our visual noise produced by poorly exposed shots. 

Most of the independent filmmakers I know are obsessed with getting very moody images in camera. They want to have shots that go from extremely dark to extremely light.  They want to record eerily dark scenes with one light or sometimes no lights.

Nothing is wrong with wanting to control each shot as much as you can. In fact, you should strive to control everything within your power. The problem is neglecting to bring enough light into the scene to get a proper exposure.

Exposure

Exposure is the amount of light (controlled by the aperture) captured over a very specific amount of time. 

Another way to define it is exposure refers to the amount of light that is let into the camera sensor. The more light allowed in the brighter the image. Conversely, the less light allowed in, the darker the image.

While the camera producers will often rant and rave about how many stops of dynamic range a camera has, the amount of really usable information usually resides within a much smaller range. 

For Digital Cameras you typically want to try to fit everything within 2 stops above or below perfect exposure. 

Anything more than two stops over will be overexposed.  This overexposure will result in a loss of image detail in the brightest areas of the photo.  Anything less than two stops under will be underexposed.  This will result in the introduction of noise.

Proper Exposure

But what is proper exposure? Proper exposure is lighting a scene that is not too bright or too dark for image details to be clearly seen without the introduction of noise or the lack of detail.

An overexposed image will have areas of the photo that are blown out or too bright for details to be seen.  There is usually very little image detail and the overexpose areas of the picture.

And under exposed image will have areas of the photo that are too dark for details of the image to be clearly seen. When the image is brightened in post-production noise is introduced to the image.

A better approach for both overexposure and underexposure is to light the image for maximum detail and create the style you want and post. That is not to say you cannot create the image you want beforehand. You definitely should come as close to your final image is possible. You just need to do it in a way that allows you the greatest amount of flexibility.

The best way to control the brightness and darkness of a scene is to light it properly.  There are a couple other ways of manipulating the exposure of a scene.

Aperture

The aperture, also known as F-stop, controls how much light hits your camera’s sensor or basically the size of the opening in the lens when a photograph is taken.

A higher aperture setting means less light is being allowed into your digital sensor.  While a lower aperture setting means more light being allowed into your digital sensor.

ISO

The ISO setting can affect the brightness of the image by altering the brightness of everything in the image.  This comes at a price, as raising the ISO introduces noise and degrades the quality of the image.

For example: Let’s say you are lighting a very moody scene in a haunted house.  The main character is holding a flashlight.  Most novice directors or cinematographers would want minimal light to convey the eerie darkness of the scene.  This is a mistake.

It is far better for you to light the scene properly while accenting it in the direction you want. In this case that may mean getting enough light on the characters and parts of the back ground you want to highlight, but allowing other areas to be slightly darker. You would then employ a super powerful flashlight, and slightly lower the light in the path of the beam to aid in its visibility.   

Beginning Lighting Setup

When lighting an interior scene it is often best to begin with a 3 point light set up featuring:

1- Key Light:  This is the main light studio light that gives the majority of the lighting to the subject.  It is usually set up at angle toward the face of the actor you wish to shoot, but on the opposite side of the camera.

2- Fill Light:  This is a light used to fill in the shadows left on the subject by the Key Light.  It is less intense than the fill light.  It lightens shadows enough to illuminate the subject while allowing enough shade to provide contrast.

3- Back light: This light is typically overhead and behind the subject.  It provides a sort or rim or halo to the silhouette of the subject, giving it depth.

Now, this is only your basic lighting setup. If you stick with just three point lighting your scene will be bland and lifeless. This is where art design and creativity, and place. It is also where you need to have a bit of lighting knowledge.

Example: you are lighting a scene with a girl sitting at the table reading a book by candlelight. You would like to be able to see her face, what she is doing, bits and pieces of the background, and give the illusion of candlelight.

If you set up to candlelight by itself it would not be enough to light the scene. You could, however create a key light coming from the general direction where the audience would perceive the candle casting a light.

Your fill light and back light would be subtle enough for her to be made out but not bright enough that it would distract the audience from the scene.  Your background light would shine on the part of the background that you want to show, but it too, would, from the basic direction of the light the candle is supposed to be throwing.

Now, let’s keep in mind what we learned earlier. There must be enough light for the shot to be exposed properly. It is far better to bring down the brightness of the shot in post-production than to introduce noise to the shot if you got it wrong during recording. 

Putting it all together

You should begin each scene with one light.  This is typically the practical light or the light that will be viewed by the audience as the light that is illuminating the scene.  Once you have established this light you can then set your key, back, and fill light.  After those lights have been established it is now time for you to stylistically choose what parts of the scene you want to show, and in what way.

There are no limits other than the limits you impose upon yourself.  After character lighting is complete your scene can look as polished as your imagination will allow.