Nailing Exposure

We will be holding another “Nailing Exposure” workshop this month. It is one of our most popular workshops and encourages anybody holding a camera to move away from the “Automatic” setting, because taking control of your camera means you’re taking control of your creative expression. This can be daunting: today’s cameras are incredibly smart, advanced. But they are also dumb. As contradictory as that sounds, it’s not. The inner workings of your camera allow it to incorporate massive amounts of information. The sensors and processors in our cameras remove much of the past’s guess work for getting proper exposure, a sharp image, and correct colors. But the camera deals in zeros and ones: it is a computer meant to solve for what constraints you have placed on it, or conversely, the constraints you place on yourself.

Let us cast off those restraints.

The Exposure Triangle

First, what do we mean by proper exposure? It means that you capture the right information for the shadows, the mid-tones, and the highlights across an image. In short, I can see all the detail I want to see in the image. Our cameras solve for the average when they are in automatic mode; however, when you solve for average, you often get average results. We’ll get back to moving beyond average, but first let’s discuss the levers our cameras use to get proper exposure.

There are three components for exposure: aperture, shutter speed and sensor sensitivity (ISO). We refer to these as the Exposure Triangle (see below). In automatic mode, our cameras determine when these three are in balance given a specific lighting situation and as the lighting changes, the camera automatically adjusts these settings to get back to balance. Some preliminary knowledge about how our cameras work is necessary.

Photography is all about capturing the light in a scene. The object that captures that light is a light-sensitive object in the back of your camera called the sensor. Think of the sensor as a blank canvas. As light travels through your lens, it hits the sensor, light paint on a canvas. We’ll revisit this analogy as our discussion progresses.

Let’s talk about each one individually, and also about the creative aspects they control when we move away from automatic settings.

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Exposure: Shutter Speed

A curtain sits in front of your sensor. It is the gatekeeper for your sensor, battling back unwelcome light! When it is closed, it turns away any light from the sensor. This gatekeeper is called the shutter.

We get to instruct the shutter how much time to allow the light to interact with the sensor. If it’s a bright, sunny day, we might tell the shutter, “You shall allow light to pass through you for only 1/200th of a second!” And that may be all that is required to get a proper exposure (dependent on the settings of the other two triangle elements).

But a creative component is also impact by the time we allow the shutter to be open. Close your eyes. Now open them and close them again at the speed of a blink. What did you see. You likely saw a snapshot of time, with items that you know are moving still appearing to freeze for that split second. Let’s do this one more time. Close your eyes. Now open them, but keep them open for a count of one second before closing them again. What did you see. This time, you likely saw some degree of movement. You may have observed your dog move eight feet from one side of your vision to another. You may have seen a baseball travel from the hand of a pitcher to the catchers glove. Why is this important?

Cameras relay information back in static! Imagery is a two dimensional representation. It has not time component. So our cameras record all the information at once.

Each of these example images demonstrate the range of creative expression with shutter speed. In the first, the shutter is open for a long time. Anything that is staying still while the shutter is moving, appear to be staying still. But anything that was moving during the time that the shutter was moving results in motion blur. This is not the same as being out of focus! This just shows the trail of motion while the shutter was open.

The second image is a fast shutter speed. The shutter is only open for a brief moment in order to freeze the motion, as if the subject is frozen in time.

And they both have proper exposure! We manipulate the other levers in order to maintain the proper exposure.

Exposure: Aperture

Aperture is controlled in the lens and represents the size of the opening that allows light through your camera on to your sensor. Think of it as a hose ejecting paint on to your canvas. The wider the hose, the more paint is allowed to hit the canvas. The smaller the hose, the less paint. Now think of a garden hose. The wider the opening to the hose, the more dispersed the water. When you tighten the opening to the hose, either with a nozzle or with your thumb, the tighter and more focused the water stream becomes.

This latter point is important for understanding the creative uses of aperture.

Aperture controls a concept called depth of field. Depth of field indicates how much of your image will be in focus from the foreground, through the background.

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Very shallow depth of field, f/1.4

A shallow depth of field means that only a small portion of what you tell your camera to focus on will be in focus. The farther away items in the scene get from that focus point, the more soft and out of focus they become. And similar to our hose analogy, the larger the opening on your lens, the more dispersed the focus, meaning a shallower depth of field. The smaller the aperture, the more focused. The key to remember is that for aperture, the smaller the number (e.g., f/1.4, f/2.0, etc.) the larger the opening. The larger the number (e.g., f/22, f/16, etc.), the smaller the opening.

Exposure: Sensor Sensitivity (ISO)

ISO is the standard for measuring how sensitive your sensor will be. Imagine two canvases with two types of material: one is cotton muslin and the other is glossy paper. When you throw paint against each, one absorbs more of the paint faster than the other. This illustrates the principles of sensor sensitivity. The higher the sensitivity of your sensor (higher ISO number), the more it is receptive to accepting the light hitting it (the more it acts like the cotton muslin). There is, however, a trade-off.

When you throw the paint against the cotton muslin, you need less paint to make an impact, but it spreads more. You can’t be as precise. Whereas, with the glossy paper, it may take more paint, but you can be more precise. A similar effect happens with ISO. As you dial up the ISO number, you can get more information, but it results in a less controlled artifact called grain. Grain looks like a crunchiness on the image, which can be appealing or not appealing.

ISO is used frequently to preserve the artistic desires of shutter and aperture. When you’ve pushed them to their limits, you use ISO to get back to proper exposure. ISO is also important in event photography like weddings when you are shooting in dim scenes. Sometimes the only way to get the shot is to tell your sensor to be extra sensitive, damn the grain!

Exposure Summary

We teach how to get proper exposure using these three levers in our workshop. It takes practice because it’s not intuitive to move them up and down. But it is worth it! You reclaim the ability to take the artistic expression in your head and translate it to the final image with much greater consistency!

Contact us if you are interested in registering for our workshop!

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