Today we are going to talk about getting the right exposure. What do you think this means? Simplified, it means maintaining a balance between light areas and dark areas of the image. We have all seen photos that are so light you can’t make out any details or so dark that it becomes a blob.
In today’s cameras there is a sensor that reads light. Generally, this is the light that is reflected off of the subject. This can be adjusted either manually where you tell the camera what to do or let the camera make the adjustments. If your camera has a live display, you can see what the photo will look like before you take the shot.
If there is an exposure compensation dial, you can dial the exposure up or down until you like what you are seeing. There also may be some presets to choose from. Portrait, Landscape, Sports and Action are just a few. The camera gets it right most of the time, but when there are shots with extreme light and dark areas, the camera will average the values and you will end of with a bland photo that didn’t capture what you remember seeing.
Let me introduce you to something called the exposure triangle. Yes, there is math in photography. The three legs are Shutter Speed, Aperture and ISO. Just like in math, when you change the value for one side of the triangle, the other two are affected.
Shutter Speed – it is how long the shutter is open. The longer it is open, the more time the light falls on the image sensor.
Aperture – how large is the opening at the back of the lens. A larger aperture will let more light in than a smaller aperture. Apertures are measured in F Stops. F 1.8 is a wide opening and F 22 is a small opening.
ISO – This measures the sensitivity of the image sensor. The larger the number, the more sensitive it is to light. The base is ISO 100, ISO 200 is twice as fast. Each time it doubles, the sensitive doubles. ISO 1600 is 4 times fast at ISO 100.
The idea of manually setting up the exposure goes way back to the film days. A good photographer had to know how to read the light and expose the film accordingly. Back in the day, he wouldn’t get to see the results until the film was developed. We have it much easier with today’s digital cameras because we can have instant feedback.
So you are asking, “Where do I start?” We can use the camera’s light meter for a place to begin. Take some test shots with your camera set to Auto Mode. Take a look and see how close your camera got to what the actual scene was. Maybe it was way off or maybe nailed it, Great! When you are looking at your photos in View Mode, you will be able to see the file information. Besides the time and date, there is also the information from the Exposure Triangle.
Now switch over to manual mode. Use these same settings and retake the shot. What did you get? Depending on the camera you are using the settings may be in a menu, changed by pressing buttons or moving a dial. Refer to your owners manual to see how it is done with your camera. In the real world, if the camera setting are the same in manual as they were in auto, Bam, you get the same shot. Now for the fun part. Change one of the settings and see how the photo is affected. Maybe turn up the ISO sensitivity to brighten the photo or close down the shutter to darken the photo by letting less light in. You will quickly see that if you only move one setting, the photo is way off. To get the same results , the trick is to change two settings at the same time. You could open the aperture wider and decrease the ISO sensitivity each by the same amount. This would let more light in, but would also decrease how sensitive the image sensor is, so the resulting photo would be the same. You could also increase the shutter speed and off set by making the image sensor more sensitive by bumping up the ISO setting. I want you to see how changing how changing the ISO, the shutter speed or maybe the aperture can drastically aspect the photos outcome. All along, this is something we have left up to the camera to decide. But we are talking about real world circumstances and taking back control of our images. Will we get it right all of the time, maybe not. But knowing how to make corrections to get a better image will improve your photography. It doesn’t matter if you are a professional photographer or just starting out, no one wants to take lousy images.
My next Posts will spend more time with each leg of the Exposure Triangle. We will see how they affect each other and how we can take control of our camera and get out of auto mode.