The Three Main Factors That Determine the Exposure of a Photograph Are Aperture, Shutter Speed, and ISO

A photograph’s exposure is determined by three things: aperture, shutter speed, and ISO. Aperture is the size of the opening in the lens through which light enters. Shutter speed is the amount of time that the camera’s shutter is open, exposing film or sensor to light. ISO is the sensitivity of the film or sensor to light.


An image’s depth of field (the range of distances from the camera that appear acceptably sharp in an image) increases with smaller aperture sizes; conversely, shallower depth of field can be achieved by using a larger aperture. Depth of field is also affected by other factors such as focal length, subject distance, and camera-to-subject distance.

In general, it can be said that wider apertures result in lower depth of field while narrower apertures increase depth of field. However, there are many other factors that affect depth of field such as focal length and subject distance so it’s best not to think about aperture in isolation when determining how much depth of field you want in an image.

There are several “stops” or “f-stops” on lenses which represent different combinations of aperture size and shutter speed that will result in equivalent exposures. For example, if you double the size of the aperture (halve the f-number), you can halve the exposure time while still letting in the same amount of light.

Shutter Speed

Shutter speed is measured in seconds or fractions of seconds. For example, 1/500th of a second is faster than 1/60th of a second. The faster the shutter speed, the less time the sensor has to be exposed to light, and vice versa.

The choice of shutter speed has two main implications: it determines how much light hits the sensor (and thus how bright or dark your photo will be), and it also affects how motion will appear in your photo. A fast shutter speed will freeze motion, while a slow shutter speed will blur it.

So what’s the best shutter speed to use? That depends on what you’re trying to photograph and what look you’re going for. In general, though, here are some guidelines: + If you want to freeze motion: Use a fast shutter speed (1/500th of a second or faster). This is useful for things like sports or other action shots where you want everything to look sharp and still. + If you want to capture movement: Use a slower shutter speed (1/60th of

second or slower). This can create cool effects like blurred waterfalls or cars streaking by on city streets


Aperture is the size of the opening in the lens through which light enters. It is measured in f-stops: the lower the number, the larger the opening. A wider aperture lets in more light and results in a brighter image, but it also has a shallower depth of field, meaning that objects in the foreground and background will be less sharp. A smaller aperture has a greater depth of field but lets in less light.

Shutter speed is how long the shutter stays open to let light reach the sensor or film. It is measured in seconds or fractions of seconds (such as 1/60). A faster shutter speed means less time for light to enter and results in a darker image; a slower shutter speed means more time for light to enter and results in a brighter image. But using a faster shutter speed can also freeze movement, while using a slower one can create blurriness (this is why it’s hard to take pictures of moving objects).

ISO measures how sensitive your camera’s sensor or film is to light-the higher ISO you use, the more sensitive it becomes (meaning you can use a faster shutter speed or smaller aperture). But using too high an ISO can result in “noise”-small speckles that appear on your image (this is why it’s important to find just The Right ISO for each situation).

So those are The Three Things That Determine Exposure! Now get out there and experiment with them to see what kinds of effects you can create!

To produce a photograph or video you must use the exposure triangle in order to balance aperture, shutter speed and ISO, and as a result, control how long and how much light enters the camera sensor

A camera’s ISO, shutter speed, and aperture work together to create an image. They are the three elements of the exposure triangle.

When you change one element of the exposure triangle, you must change at least one other to maintain the same overall exposure. For example, if you double the ISO, you can half the shutter speed or f-stop. This relationship is known as the reciprocity law.

The key to understanding how these three elements work together is understanding that they each control different aspects of an image:

ISO controls how sensitive your camera sensor is to light. A higher ISO setting will make your sensor more sensitive, resulting in brighter images. However, it also comes with a trade-off: higher ISOs can introduce noise into your photos.

Shutter speed controls how long your camera’s shutter stays open while taking a photo. A longer shutter speed will result in a brighter image (because more light is entering the camera), but it will also cause any moving objects in your frame to appear blurry. A shorter shutter speed will make moving objects appear sharper at the expense of a darker image overall.

Aperture (sometimes called “f-stop”) controls how much light enters your camera when taking a photo. A wider aperture (represented by a smaller f-number) lets in more light than a narrower aperture (represented by a larger f-number). Wider apertures are great for low-light situations and for creating shallow depth of field effects, while narrower apertures are better for well-lit scenes and for achieving greater depth of field .

I'm a photography enthusiast with a passion for classic film cameras and writing. I believe that photography is a powerful tool for storytelling and I strive to create images that are evocative and meaningful. I hope you enjoy my work!