2.4: Exposure values compensation

Last updated
Save as PDF

Page ID: 151079

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Notice that the following photo is too dark. This is because there was not enough light. But, the picture was not taken when the weather was not bad outside; what was the problem? Now is a good time to talk about the relationship between light and exposure. The amount of light that strikes the camera’s sensor is controlled by two factors: how much light is let into the camera (via the aperture) and how long the light is on the sensor (shutter speed). Usually your camera automatically calculates these setting scene.However, if the camera reads incorrectly the scene and overexposes an image, you will want to correct the setting and shoot again. To compensate for this potential problem, most digital cameras offer a setting called Exposure Value (EV) that lets you make small changes to increase or
decrease the exposure of the photo.

Exposure Value (EV)

Automatic setting which controls how much light is let into the camera (via aperture) and how long the light is on the sensor (shutter speed) Changing the EV is easier than changing shutter speed or aperture value, so EV has simple steps to automatically increase or decrease both shutter speed and aperture value

Changing EV value

+ value increases the exposure to increase backlighting
- value decreases the exposure to increase backlighting

Examples of changing EV value

When should you change the EV value? The camera usually calculates an appropriate exposure automatically. For example, when you take a picture of sunset, your camera will increase exposure because of the lack of light. Your photo of the sunset will be brighter than what you look at. At that time, you can decrease the EV value; then, your photo will illustrate a real sunset atmosphere.

TIP: Using Auto Bracketing

quick and easy way to get the best exposure is to use the auto bracketing menu in your digital camera. More and more cameras are now offering an auto bracketing feature that automatically changes the setting each time you take a photo. If you turn on the bracket function, the camera will take several photos (generally three) each at a different EV setting You select the number of EV steps that the camera offers and the range of EV settings. For example, the shot may be taken at -.5, normal, +.5.

This auto bracketing function is useful for taking pictures of static subjects such as
landscapes.