Shutter speed, aperture, iso – photography.


Just picked up the hobby(photography), can some explain these terms and how the affect each other?

In: 4

A camera captures an image by recording light that passes through the lens onto the sensor.

ISO: the sensitivity of the sensor to that light. Higher ISO turns up the gain and makes the sensor more sensitive to the light.

Aperture: the size of the opening in the lens that the light passes through. A smaller number is a bigger opening. A bigger number is a smaller opening.

Shutter speed: the amount of time that the shutter is open, allowing light to pass through the opening in the lens onto the sensor.

You control exposure by adjusting these variables.

1/100 shutter speed and f/8 aperture gets you the same exposure as 1/200 shutter speed and f/4 aperture. You’ve halved the amount to time that light is allowed to flow onto the sensor, but you’ve doubled the size of the opening in the lens so twice as much light can flow through.

1/100 shutter speed at f/8 aperture and ISO 100 gets you the same exposure as 1/200 shutter speed at f/8 aperture and ISO 200. You’ve left the lens opening at the same size, so the same amount of light is flowing through. You’ve cut the amount of time that the light can flow onto the sensor in half, but you’ve doubled how sensitive the sensor is to that light.

There are lots of other things going on when you make adjustments to these variables, but this is how they relate to exposure.

Buy the book Understanding Exposure by Bryan Peterson. It’s been one of the most common reads for new photographers for the past 20 years.

Think of a photograph as a bucket of light. You need to fill the bucket to get a good photo. But, too much and you make a mess. Too little, and you can’t see anything.

ISO- how big is the bucket.

Aperture- how much light comes in at one time (how fast the water flows)

Shutter speed- how long you let in the light (how long you run the water)

There’s lots of ways to fill the bucket. You can trickle the light in (small aperture, long shutter speed). You can dump in as much light as possible as quickly as possible (large aperture, short shutter speed). Or something in the middle.

Shutter speed is probably the most important for someone just starting. A long shutter speed means you are more likely to get blurry pictures. A short one means you will get crisper photos.

Aperture impacts how much of a photo is in focus at once. You know how people say to turn a light on to see better? That’s making the aperture of your eye (pupil) as small as possible to increase the focal depth. A really small aperture will have a lot more in focus at once. A really large aperture will have a very narrow focal plane.

You can tweak your iso to manipulate how much light you need. A lower iso means you need more light (bigger aperture, longer shutter speeds), a higher means less light (smaller aperture, shorter shutter speeds). On film, a higher iso was less precise than a lower iso, but was better at capturing action shots.

Each part can be manipulated to get certain effects.

Want to blur the foreground and background? Small aperture. Want to focus on just one thing? Big aperture.

Want to capture something going very fast? Short shutter speed.

Want to make something look blurry/look like it’s going really fast? Longer shutter speed, smaller aperture.