How to Control Exposure on a DSLR

In this video...

I discuss the three basic settings that give you total control over your exposure. Below is the rough transcript.


Transcript

One of the first things you need to learn as a photographer or filmmaker is how to control exposure.

If you're unfamiliar with the term, exposure simply means the brightness of your image.

There are three main settings that affect the exposure of your image. They are ISO, Shutter Speed, and Aperture. 

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ISO

This is basically the gain setting of your camera. As you turn it up the image gets brighter, but it also gets noisier.

While some cameras handle high ISO settings better than others, it's pretty much universal that a high ISO means a brighter, noisier image, while a low ISO means a darker, cleaner image.

Shutter Speed

The shutter speed controls the motion of the moving objects in the image.

A lower shutter speed makes a brighter image while giving the moving objects more of a blur.

A higher shutter speed means a darker image with motion that is crisp and jittery. 

As a starting point, if you want your image to look cinematic, and you're shooting at 24 frames per second, you want your shutter speed to be at 50. That's double your frame rate, or as close to double as possible.

This creates a standard, base line blur in the moving objects in your image. I wouldn't recommend adjusting the brightness of your image with the shutter speed first. 

Aperture

The aperture is the opening in the lens that let's light in. Aperture is measured in f-stops. "Iris," refers to the mechanism in the lens that creates the opening. (See the video for a visual explanation.) Most of the time the words "Aperture," "F-stop," and "Iris" are used interchangeably.

A small aperture (like f/22) lets in less light and deepens the area that is in focus. A wider the aperture (such as f/1.8) lets in more light and creates a shallow area of focus, or “depth of field.”

Having a shallow depth of field is one thing that can make your image look great, but it’s not quite as vital to a cinematic image as many people think. When you watch movies closely, you’ll see that not every shot has an extremely shallow depth of field. 

This means that of the three factors that affect exposure, the one I’ll adjust first is the aperture. This gets rid of some of my blurry background, but it ensures I don’t have a noisy image (like I would if I cranked the ISO), or a jittery image (like I would if I crunked the shutter speed).

If you’re wanting to up your game as a photographer or filmmaker and you don’t know these settings perfectly, work on learning them like you would learn a language. It may be difficult to keep straight at first, but the more you force yourself to shoot using these manual settings, the more they’ll become second nature to you.

The shooter inside you will thank you.

Final Tip:

If you can’t get your image dark enough by using only your aperture, you can get an ND filter to put on your lens. I made a short video explaining that here.