Wikipedia defines exposure as…
“…the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance.”
Simply put, exposure is the final process of photography where your camera literally “opens” and allows light to hit a light sensitive medium (either a digital sensor or a film strip). When the camera closes and stops letting light in, the exposure is complete.
A photo has been taken.
As exposure is the final process to taking a photo. if you mess this “finale” up, you’ll mess up everything else that went ahead of it.
- Compose a great photo but fail with exposure = bad photo
- Find spectacular light but fail with exposure = bad photo
- Encounter a once-in-a-lifetime moment but fail with exposure = misery for weeks
The less you understand how to use your camera, the more likely you’ll mess up the “finale” of exposure and fail to catch the beauty you saw.
Herein is the reason why so many beginner and amateur photographers struggle with exposure.
Plain and simple, cameras are complicated.
There are so many settings, modes, and bells & whistles that it’s easy to get overwhelmed. Fortunately, exposure isn’t as hard as it seems.
There are really just three settings you need to know:
- Shutter Speed
They all interact together to create an image, as the video below shows.
Every time you take a picture, these three settings are selected. Your choice of camera exposure mode determines just how these settings are chosen.
Living in Automatic Mode
Automatic mode is a great mode when you’re in a rush or have little time to take a shot.
For example, if your in the jungle and keep unexpectedly running into jaguars and anacondas, fully automatic mode is great.
Its better to capture the moment (in automatic mode) than not to capture it.
The rest of the time it isn’t so great.
Most fully automatic modes will create an “Average guess” of what seems to be the best settings.
Leaving your photo up to a “guess” is like asking a random stranger to babysit your baby.
Each photo you take has a different challenge and different goals.
Having your camera “guess” what settings are best for your photo is definitely a Photography Sin.
AUTO MODE is the equivalent of ‘writing by hand’.
It just sucks most of the time. And if you’re a more advanced photography, you probably nodded your head like a bobble head after reading that.
When you know how to expose an image correctly, photography becomes much, much easier.
Ok. Let’s continue.
Photos that Are Too Dark/Bright
Improper camera exposure can make your photo too dark or bright.
If you are using an automatic camera and are in auto mode then to ensure your photo is bright you really should start learning how to use the meter modes in your camera. If you have an SLR your camera should have a built-in light meter.
Now we’re going to dive into camera exposure. There’s a whole lotta stuff to cover. So get ready.
The Three Main Elements of Exposure
Exposure, as we’ve discovered, has three parts to it:
- Shutter Speed
All three of these settings interact to create an exposure. Each setting, however, has it’s own influence on the image:
When you take a picture, your camera opens it’s aperture( basically the eye) and lets light in. How long light is let in is controlled by the shutter speed.
Using the shutter speed correctly is just a matter of selecting the right shutter for the amount of light available.
For dark areas, more light is needed. So that means a longer shutter speed. And for a bright area, like the beach, less light is needed. So a faster shutter speed is used.
You can creatively use the shutter speed in many different ways.
It is often used for cool blur effects of fast moving objects such as the picture to the left.
As a general rule, you are going to want to use a tripod for slow shutter speeds.
If you don’t, your image could end up being too blurred.
Your goal is to have the moving object blurred and everything else very sharp and clear. Having everything blurry ruins the whole purpose.
When taking photos of fast moving objects and your goal is to “Freeze” the objects…
People moving quickly, playing
Fast moving water
Shooting out of a car
When taking photos of fast moving objects and your goal is to “Blur” the objects…
Cars, traffic, etc
The aperture is basically an opening that controls how much light is let into your camera. The size of your aperture also controls your images depth of field, or how clear your image is from foreground to background.
The smaller the opening, the more expansive your depth of field will be, creating a clearer, more detailed image. For example a small aperture opening of around F/16 will make the entire image in focus.
Small apertures are great when you are taking shots of large amounts of space like stadiums, landscapes, etc.
The photo to the left of the large city view, for example, has a very large aperture to allow the entire scene to be sharp and in focus.
Large apertures, in contrast, create shallow depth of field which basically causes a photo to have one point in focus and objects in the background out of focus. It can be used in many other ways as well. Extremely large apertures can result in, for example, a person’s nose being in focus and the rest of their face being out of focus (with a close up photo of their face).
Unlike aperture and shutter speed, both of which can be used to produce varying visual effects (depth and blur), the only effect ISO makes is noise when used in excess.
ISO, however, is an important setting that is critical to understand if you want to get the most out of aperture and shutter.
Simply put, your ISO controls how sensitive your camera is to available light. A low ISO makes your camera less sensitive, creating a higher quality image. The higher up your ISO, the more sensitive your camera is to light. This also has an added consequence of noise.
Extremely high ISO’s of 3200 and above will produce grainy images. With that said, if you’re in a dark area and the only way you can capture the photo is with a high ISO, it’s better to have a sharp image with grain than a blurry image.
Tying the Three Together With Exposure Modes
So we’ve got a brief overview of the three primary exposure settings. How you choose to select and use these settings is controlled by the exposure mode.
There are many different modes that you can expose in. Each has its own added advantage (and drawback).
Shutter Priority Mode
This mode lets you control how long light is let into your camera. The aperture is then automatically adjusted to this length of light let in.
This is the best option when you want to avoid blur or are in certain settings. For example, in very bright settings you want to use a shutter that is fast.
Whereas a dark area would require a longer exposure for the light.
Aperture Priority Mode
This mode lets you control the amount of light that is let in through the aperture of the camera.
A larger aperture means more light will be let in. This is good for scenes without much light like the shade or indoors.
A small aperture is good for bright settings or scenes that you want lots of depth focused.
In this mode, the shutter is automatically adjusted to the aperture to properly expose the shot.
Manual mode is more complex. You must properly select the correct shutter and the aperture. You need a light meter to do this properly. Most cameras have one built into them.
This is really not a mode to start using until you’re more familiar with the settings.
Experiment With Everything
Camera exposure is really something you can only understand after practicing it.
Try using different exposure modes in different light situations.
- Full sunny days
- Cloudy days
- In the shade
- During sunset
You’ll get pretty accustomed to this.