Title: READ: Exposure & Metering
Course: Digital Photography

Exposure & Metering

Exposure & Metering

Often the most difficult part of taking a photo is getting the correct exposure. A good even exposure gives detain in the shadows and details in the brighter portions of your photo. You light meter will be your friend when working with exposure.

A photo that is under exposed is dark and looses details because they are lost in the dark. An overexposed photo is too light and your details are whitewashed from your photo. An over exposed photo is often more damaging to your photo because it is harder to fix using software. Detail lost to whitewashing is often irretrievable whereas details lost to slightly under exposure can often be brought back to life with you editing software later.

Sometimes, you may not want even exposure for your photo. Maybe you want to set your camera so only the subject is exposed for or maybe you don't want the background to show up and under expose the foreground.

Exposure is controlled by the amount of light coming in through you lens. Yes, you guessed it - that means you can control your exposure by changing the shutter speed and aperture. The other thing that plays into your exposure is the camera’s ISO setting. If you remember the ISO is basically a gain added to you cameras sensor making it more sensitive to light. The metering setting in your camera will decide what and how to expose your photo. It takes the bright and dark levels I your scene and convert them into shutter speed and aperture values.

How the metering is decided is based on usually one of three settings in your camera. Most cameras you can set it to use a Matrix, Center-weighted, and spot. Your camera may call these by different names like average, point, etc. you will need to look at you camera to find out.

Matrix – This will take everything in your scene into account and then calculate the correct exposure so everything will be exposed equally. It will compare the photo with thousands of photos in your camera’s database and decide what will be the best. Use this setting if you want to try to get as much detail from everything in your photo. A good time to use this is when the light is coming from over your shoulder and when you don't have an excessive contrast of brightness (very deep shadows). See examples of matrix metering HERE.

Center-weighted – This setting will only use the light information coming from the center of your lens (some cameras let you set what portion of the lenses to average from). This setting will expose only for the average of the center of your photo. Use this if you don’t care about getting the correct exposure for the rest of your photo but you want to get a large portion of you subject to be exposed correctly. The exposure lock can be useful when using this setting. Set you camera to expose for what you want and then lock in the exposure and re-frame your scene. This is often good when you have harsh directional light that is lighting up a portion of your scene but may not be lighting up your main subject. Examples: bright sky and dark ground. See examples of center-weighted metering HERE.

Spot meter – This setting will let you choose a small portion of what you are looking at to expose for. The rest of the photo may not be exposed correctly but the small spot you set will look perfect. This is often useful when the main subject falls within its own shadow (the main light source is behind the subject). This good to use if the contrast in your scene is high and/or you want to saturate an area with in your scene. See examples of spot metering HERE.

When deciding what metering mode to use ask yourself the question: what in this frame do I want to emphasize? As you take photos and look at different scenes you will start seeing how light is affecting the photo; this will allow you to be more creative when using your metering settings. Here is the order you will often find yourself using when deciding on the correct metering/exposure setting.

1. Choose a scene
2. What is unique about the scene?
3. What light plays a role in that uniqueness? This will be your metering setting
4. What exposure program should I use: A,S,P. This is based of movement, depth of field, etc. If you can’t get the exposure for the setting you want you will probably want Manual Exposure (M Mode). You will use your light meter for this.

For manual exposure mode just find what the camera suggests and then adjust the exposure to your creative liking. You can use your light meter scale to find out what settings are in the suggested range.

Flash Compensation -
The next thing you need to know about exposure is how to adjust for your flash. Have you ever taken a photo where your subject is whitewashed because of your bright flash? You can fix this by using your flash compensation. This adjusts the brightness of the subject relative to the background. This is done by adjusting your shutter speed and timing so that you subject is not bleached and your shutter stays open long enough for your background to be light by the flash.