Understanding Your Equipment: Part 1 - The 3 Elements of Exposure
Ok. I know the title of this post sounds like a bad title to a beginners photography book but it's not. Actually it probably is. But I don't care because I think it is SO IMPORTANT that a photographer understands their camera before shooting anything seriously. As a matter of fact I don't think you can call yourself a photographer if you don't fully understand the camera. That means understanding the settings and how those settings effect each other. After all, you want to use all of the camera's potential to get the best photographs possible. So I've decided to make this a series on not only understanding your camera but your equipment in general. In this case its really only going to include the camera and speedlights and how they work together and separately.
I'm going to try to put these in the simplest of terms. SO, first things first. Understanding exposure. The three components of exposure are:
1. Aperture: The aperture is the opening or hole in the camera that allows light to travel through it and hit the image sensor. This hole will get bigger or smaller depending on the aperture setting a.k.a f-stop number. The higher the number ( f 16 or f 22) means that the hole is very small and therefore is letting in a very small amount of light. The lower the number a.k.a a wide aperture (f 1.4 or f 2.8) the larger the hole becomes and lets in a large amount of light. The aperture also controls your depth of field. The wider the aperture (f 1.4) the smaller or narrower the depth of field will be. This means isolating your subject and keeping it in focus while everything else is out of focus. The smaller the aperture or bigger the number (f 22) the greater the depth of field making almost everything in focus. Here's a diagram (the diagrams are not in their full scales, they are just to give you an idea.)
2. Shutter Speed: The shutter speed a.k.a exposure time is how long the camera's shutter stays open to allow light to reach the sensor. It is measured in seconds (1 sec.) and fractions of seconds (1/500 sec.) If you're not sure, fractions of seconds are pronounced "one five-hundredth of a second (1/500 sec.)". The shorter the fraction time (1/1000 sec.) the less light that reaches the sensor. The longer the fraction time (1/60 sec.) the more light reaches the sensor. Long exposure times are called slow shutter speeds and short exposure times are called fast shutter speeds. Not only does the shutter speed have an effect on exposure it also controls the movement in the photograph. A fast shutter speed (1/250 sec. or higher) will freeze the action and a slow shutter speed (1/30 sec.) will blur the movements. Here's a diagram.
3. ISO: Pronounced I-S-O or I-SO. The ISO is the image sensor's sensitivity to light. The lower the ISO (ISO 100), the less sensitive the sensor is to light forcing you to use a wider aperture (f 2.8) and/or slower shutter speed (1/60 sec.) to find the proper exposure. The higher the ISO (ISO 800), the more sensitive the sensor is to light forcing you to use a smaller aperture (f 5) and/or a faster shutter speed (1/500 sec.). When you use a high ISO you will also get a lot of grain/noise in the picture. Therefore you should always try to use the lowest ISO possible for your photographs to minimize the grain. This can't really be shown in a diagram so I'm going to try to get together a few images in the next few days to give you guys an idea of what I'm talking about.
THAT'S IT. Not so bad right? It's really easy once you get the hang of it. In the next part of the series I'm going to show you examples of how all three of these work together and help you understand why you need to know all three elements individually to understand how they work together. If you have any questions just comment the post or even email me, but until then.
P.S. Special thanks to Rebekah Hoyts blog. I learned how to make these diagrams from her videos : )