Photo 102: A Not-So-Quick Lesson in Vocabulary
I’m not a professional photographer and would never claim to be one. But chances are you aren’t one either. But maybe you want to get better at making images, and you don’t know where to start. This is for you, fam.
Because I have realistic expectations, I know you probably didn’t look up all those photography terms from the last time I moonlighted as a photographer on the BOF blog. That’s okay. I wouldn’t do extra homework, either. After all, I didn’t graduate from a fancy college just to do more homework after getting a degree.
So here’s a quick-and-dirty, super simplified breakdown of these terms, which I think are the most important and relevant to your understanding of how photography works on a technical level.
An exposure refers to how much light is captured. This is important because with our newfangled fancy camera, we have a finer degree of control over exposure. Now, exposures are very much a Goldilocks-type situation. You can underexpose — that means the photo is darker, more shadowy; or overexpose — that means the photo is brighter and tends to be washed out. While you can under- or overexpose for creative effect, generally speaking, you want a proper exposure that’s right in the middle. Think about it. If a photo is super dark, you can’t see anything in it. Same story if it’s washed out and bright. And if you can’t see anything in the photo, what was the point of taking it?
SHUTTER SPEED, APERTURE, AND ISO
There are three primary means by which we can control exposures. They are shutter speed, aperture, and ISO.
SHUTTER SPEED refers to the amount of time a camera’s sensor (where the film would be in an old-school camera) is exposed to the scene. The longer the shutter is open, the more light comes in.
APERTURE is the size of the hole letting that light in. These are indicated in f-stops. The smaller the f-stop number, the bigger the hole. For instance, at f/1.8, the aperture is much wider than at f/16.
ISO is the sensitivity of a camera’s sensor to light. It used to correspond to the specific chemical makeup of film, but nowadays, it’s kind of an arbitrary indicator on digital cameras. The usage convention remains the same, however. The lower the ISO number, the less sensitive. For example, ISO200 will not pick up as much light as ISO800.
Now, I wish I could just leave you with this already-overwhelming brain dump, but the fact is there are secondary considerations for each factor here.
Shutter speeds can affect how sharp an image is. Action/movement + slow shutter speeds = blur. Conversely, a fast shutter speed can freeze motion in a photograph.
LEFT: 14mm, f/22, 10s, ISO200 — Notice how the shutter speed of 10s has resulted in blurry soccer players as they move around the field. The camera was placed on a tripod, so the soccer players are the only things in this frame moving relative to the camera.
RIGHT: 35mm, f/2, 1/850s, ISO200 — On the other hand, a shutter speed of 1/850s is fast enough to freeze action. This car is coming through the turn north of 50mph. However, notice how the wheel spokes are discernible, and how dirt clods are seemingly suspended in air.
DEPTH OF FIELD
Depth of field is basically how much of your scene is in focus. Shallow depth of field means very little of the scene is in focus. That can be desirable when you want to emphasize a subject and blur out the background. Conversely, if your DOF is too shallow, it’s possible not enough of your subject will be in focus. Your DOF is affected by aperture, as well as your relative distance from the subject. Lower f-stop number = shallower DOF; higher f-stop number = greater DOF. The further away from your subject, the more of it will be in focus for a given f-stop.
LEFT: 23mm, f/2, 1/900 — Because our aperture is set to f/2, we have a shallower depth of field. We are also extremely close to Lu, which further exaggerates this shallow DOF. In this example, only Lu’s nose is in focus. The rest of his face—his eyes, teeth, ears—are slightly blurry and out of focus.
RIGHT: 27.7mm, f/8, 1/850 — In this image, the relative distance between camera and subject and higher f-stop number allows for more of the frame to appear in focus.
On lots of cameras, the trade-off for gaining light sensitivity via higher ISO is more digital noise. Noise can muddle a photo and introduce digital artifacts that alter an image’s sharpness and color reproduction. As a result, I try to keep ISO as low as possible for the given situation. That said, most modern cameras handle noise just fine, and this isn’t as big of a concern, especially for images that aren’t being reproduced at billboard scale.
LEFT: 42.5mm, f/8, ISO200 — This image is taken at the lowest possible ISO for a cleaner file.
RIGHT: 42.5mm, f/8, ISO12800 — Notice the image quality difference, especially in the out of focus areas where the red and beige meet. Instead of a smooth, creamy, out of focus area, the image looks prickly, grainy, and muddled.
For each photograph, shutter speed, aperture, and ISO are working in unison. You have to make choices based on what kind of photograph you want and what scenario you have before you.
I know this is a lot of technical information, and it can be hard to digest without seeing how it works IRL. That’s okay. You’re in luck, because the next time I show up on this blog, I’ll tell you what settings I actually use to navigate all this complexity.
Originally published on the [Brains on Fire blog] on October 3, 2016.