Understanding Photography

Exposure , ISO, Shutter Speed, Aperture - A beginner's guide

It is not easy to take good pictures without having a solid understanding of ISO, Shutter Speed and Aperture –  known as the Exposure Triangle. While most new DSLRs have “Auto” modes that automatically pick the right shutter speed, aperture and ISO for your exposure, using an Auto mode limits what you can achieve with your camera. In many cases, the camera has to guess what the right exposure should be by evaluating the amount of light that passes through the lens. A good understanding on how ISO, shutter speed and aperture work together allows photographers to fully take charge of the situation by manually controlling the camera. Knowing how to adjust the settings of the camera when needed, helps to get the best out of your camera and push it to its limits to shoot the right picture.

Each of the three aspects of the triangle relate to light and how it enters and interacts with the camera.

It is at the intersection of these three elements that an image’s exposure is worked out.

ISO is a measure of the sensitivity of your camera’s sensor to light.The higher the ISO value, the more sensitive the sensor. For example, a camera set to an ISO value of 200 is twice as sensitive as an ISO value of 100. This is a very important point, so I’ll repeat it: if you double the ISO value, you double the sensitivity. Typical ISO values are 100, 200, 400, 800, 1600, 3200 etc.

Aperture is referred to the lens diaphragm opening inside a photographic lens. The size of the diaphragm opening in a camera lens REGULATES amount of light passes through onto the film inside the camera the moment when the shutter curtain in camera opens during an exposure process. The size of an aperture in a lens can either be a fixed or the most popular form in an adjustable type (like an SLR camera). Aperture size is usually calibrated in f-numbers or f-stops. i.e. those little numbers engraved on the lens barrel like f22 (f/22),16 (f/16), f/11, f/8.0, f/5.6, f/4.0, f/2.8, f/2.0, f/1.8 etc. Each of this value represents one time the amount of light either more or less in quantity. Meaning to say, f/16 will let in 1X the amount of light than a diaphragm opening of f/22 and so forth; while on the other hand, an aperture of f/4.0 will let in 1X lesser than that of f/2.8 etc.

What is shutter speed ? The aperture diaphragm of a lens (bigger or smaller values) and timing (open and close) of the camera's shutter curtain. Both perform the tasks of regulating the amount of light entering the camera. The shutter speed scales via some flickering digital numerals on the LCD screen like: 1/8000, 1/4000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1 or -1, -2 etc. are essentially indicators of the duration (timing) at which the shutter curtain opens up and closes during an exposure process. A 1/125 setting means the shutter curtain open and close within one hundred and twenty five of a second while 1 means an one full-second the shutter opens up during exposure to absorb the available light source onto the film to form an exposure.

Most importantly – a change in one of the elements will impact the others. This means that you can never really isolate just one of the elements alone but always need to have the others in the back of your mind.

I gathered this info from different Internet sources which I found to be most "on point". I hope it is helpful in case you wanna extend your knowledge in photography.

Feel free to leave questions or comments in the section below.