What Do Those Numbers on Your Camera Mean?
Friends of mine (many times moms who want to capture their children’s everyday experiences) often ask me to help them use their cameras wisely. I love this question, but often feel I don’t have the time to answer it quickly. Hence, this blog post.
The following is a preliminary overview of the three elements involved in exposing an image. This will take time and practice to understand and implement.
There are 3 elements that your camera uses to expose an image. These elements are all related to one another and are often represented by the exposure triangle. Changing one element will affect the others. These elements are:
1. ISO. Your camera is sensitive to light, so you have to tell it how bright the scene is. ISO is denoted by numbers ranging from roughly 100 (used for bright light) to 6400 (used for dim light).
2. Shutter Speed. Shutter speed controls motion. Shutter speeds can range from 1 second (this is slow so use a tripod to avoid camera shake) to fractions of a second (this is faster and, on the higher end, will freeze action).
3. Aperture or f-stop. Aperture controls depth of field, or how much you want in focus from you, the photographer, to the horizon. Use f2.8 when you want very little of your subject in focus and f22 when you want everything in focus.
Now let’s talk about some situations and how you can apply these elements. I’ll use some family pictures I took on a recent trip to a dude ranch in Wyoming to illustrate various uses of ISO, shutter speed, and aperture.
ISO - Where are you taking pictures?
OUTSIDE: Imagine it’s a warm and sunny summer day on a dude ranch in Wyoming. If you need sunglasses because it’s so bright, set your ISO to a low number like 100, like I did here with these horses grazing in the pasture.
INSIDE: Even if you have a ton of window light in your home, it's darker inside than it is outside. In this cabin, with some daylight coming in from outside, it was still dark enough for me to dial my ISO UP to 800. However, when I photograph weddings, I can easily find my ISO set at 6400, depending on the venue and circumstances.
Shutter Speed - How much activity is in the scene?
LITTLE ACTIVITY: In this scene, I caught my niece and brother-in-law looking down at the rolling river beneath them. I photographed this scene at 1/250th of a second, but you can probably use 1/60th of a second for people who are standing still. This may seem fast, but remember, shutter speed relates to motion and no matter how still we are as photographers, we’re still living, breathing human beings that move slightly even while seemingly not moving at all. I usually photograph subjects who are moving (see: kids), so I generally stick with a higher shutter speed.
LOTS OF ACTION: My niece and nephew were running around the ranch and I wanted to make sure to capture them. I knew I had to freeze their motion (otherwise my nephew would be a blurry figure), so I used a fast shutter speed of 1/500th of a second.
Aperture - How much do you want in focus?
EVERYTHING IN FOCUS: We were in the mountains and the scene was breathtaking. I wanted a picture of my sister against this backdrop while keeping some of both the foreground and background in focus so, I closed down my aperture down to f8. If I really wanted the mountains to be in focus, I would’ve closed my aperture all the way down to f22. This is the sort of thing landscape photographers generally do to get most of their images in focus.
SELECT FOCUS: With my family in the foreground at sunset, I thought it would be nice if the mountains behind them weren’t in focus because you can still get a feeling for the landscape. The silhouette of the mountains against the sky is enough to set the scene. I had my aperture opened up to f5.6, but if you really want to push open an aperture, try 2.8.
And now comes the confusing part. All of these elements (ISO, Shutter Speed, and Aperture) work in relation to one another and changing one means changing at least one more element to balance exposure. It’s kind of like a teeter-totter if a teeter-totter had three ends...?
For now, your light meter in your camera will tell you how to expose an image properly. When you’re looking into your viewfinder or at the back of your camera when the LCD’s lit up, it’s that straight line that has a bunch of ticks, a “-” sign at one end and a “+” sign at the other. If you point your camera where you want to take a picture, you want your meter highlighted right in the middle.
If you’re just starting out with your camera and photography in general, but want to take pictures of your family with something other than your iphone, put your DSLR on ‘auto’ exposure mode but start to notice what your camera chooses to do. While you observe the different ways the camera adjusts for changing light (because light is always changing,) look at your pictures and notice what happened with each of the three elements. Keep at it and you will soon be able to tell the camera what you want it to do instead of the other way around. You can also try workshops at places like NESOP to learn even more.
