Exposure Triangle

The Exposure Triangle cconsists of  aperture, shutter speed, and ISO. These three regulate the sensitivity and the amount of light that gets to a camera's sensor.

APERTURE

Aperture refers to the amount of light that passes through the camera lens to the image sensor.

The aperture mechanism in the lens, which allows more or less light to enter, is made up of a series of opaque "blades" called diaphragms. When the blades are open, your camera sensor will capture more light, whereas as the blades close, less light will hit your sensor.

HOW TO MEASURE APERTURE

The aperture is measured in F/stops. The ratio of the lens's focal length to the entry pupil's diameter is known as an f-stop (or f-number).

An aperture opening with a lower value, like f/4, is bigger than one with a higher value, like f/8. In other words, a low f-stop indicates a large or open aperture.

EFFECT OF APERTURE ON EXPOSURE

The aperture (F/stop) affects the exposure of an image inversely.  

Lower f/stops give more exposure because they represent the larger apertures, while the higher f/stops give less exposure because they represent smaller apertures.

EFFECT OF APERTURE ON DEPTH OF FIELD

The depth of field (DOF) is the percentage of your image that is in focus.

A shallow depth of means only a small part of the image would be in focus. A deep depth of field means an image is sharp from the foreground all the way to the background.

ISO

ISO refers to the camera's sensitivity to light, whether it uses film or a digital sensor. A lower ISO value indicates less sensitivity to light, whereas a higher ISO indicates greater sensitivity.

Your photos will become brighter as you increase the ISO setting. As a result, ISO can help you capture images in low-light situations.

However, increasing your ISO has ramifications. A photo taken at an excessively high ISO will have a lot of grain, also known as noise, and may not be usable. As a result, brightening a photo with ISO is always a trade-off. Only increase the ISO if you are unable to brighten the image using the shutter speed or aperture.

HOW TO MEASURE IS ISO

A logarithmic scale is used to calculate ISO. The image becomes one stop brighter when the ISO value is doubled. 

Thus, the brightness difference between ISO 100 and ISO 200 images is equal to that between ISO 800 and ISO 1600 images. Most digital cameras have ISO values that ranges between ISO 100 to ISO 12800.

EFFECT OF ISO ON EXPOSURE

ISO works in conjunction with the other two exposure variables, aperture and shutter speed, to determine an image's overall brightness level. 

With an ISO of 100, your image may appear dark. Increase the ISO to 200 to make your image brighter. Increase it to 400, and your image will become even brighter. If you shoot a scene in low light, such as at night or at an indoor event, your photos may turn out dark. Increase the ISO, however, and your images will brighten dramatically.

ISO AND NOISE 

Noise also known as grains is a type of visual distortion that occurs in digital photographs. When it's bad, it looks like splotches of discoloration and can ruin a photograph. 

Digital noise happens when shooting with high ISO to significantly brighten up your image. Having noise in your photos is usually undesirable as it lowers the overall quality of the image.

SHUTTER SPEED

Shutter speed in photography refers to the amount of time the camera shutter is open in order to capture light while creating an image .

The sensor in film and digital cameras is protected by a thin "curtain" that regulates the amount of light that passes through the lens. The shutter is the name given to this "curtain."  

Shutter speeds that are longer (slower), allow more light onto the camera's sensor or film, while shutter speeds that are shorter (faster) allow less light into the camera. In addition, shorter shutter speeds generally freeze motion, whereas longer shutter speeds allow for motion blur.

HOW TO MEASURE SHUTTER SPEED

Shutter speeds are expressed in seconds or fractions of seconds. For instance, a shutter speed of 1/100 denotes 1/100th of a second, or 0.01 seconds. Due to the length of time the sensor is exposed to light, this is also referred to as the "exposure time." 

Digital cameras also have a "Bulb" mode where you can keep the shutter open for however long you like.

FAST SHUTTER SPEED

We refer to fast shutter speed when the camera shutter is open for a very short period of time.

Fast shutter speeds are typically used to shorten the exposure time and freeze the moment. Fast shutter speeds, for example, are used in wildlife photography to capture a bird flying in the sky.

SLOW SHUTTER SPEED

A slow shutter speed, on the other hand, occurs when the camera shutter remains open for an extended period of time. Slow shutter speeds are used to lengthen the exposure time and capture movement. For example, you can photograph light trails using a slow shutter speed.