May 25, 2015

The Fundamentals of Exposure

Introduction

This tutorial aims to explain the basics of exposure and is intended for beginners who until now have let their camera take care of everything in auto mode.  This is the guide for you if you want to understand how exposure works and how different exposure settings for the same scene can produce vastly different results. In other words, we will explain how to take creative control by using semi-automatic and manual exposure settings.  We will explain the role of shutter speed, aperture, and ISO, and we will also discuss the fundamentals of ambient light and metering.

In this article we will aim to explain "correct exposure".  In other words, you will learn how to achieve proper exposure from a technical standpoint, such that details in bright and dark areas of your photos (shadows and highlights) are preserved to the extent possible.  Once you've mastered this, you can go for "creatively correct exposure", where photographers seek certain effects by deliberately altering the otherwise-correct exposure to achieve a high-key or low-key image, for instance.

As we shall see there are several correct exposures for any given scene, and they can yield completely different images.  This is why we're interested in taking manual control of the exposure in the first place!