Learn Photography Basics – The Big Exposure Three – Aperture, Shutter Speed, ISO


Photography is an art, it has been said it has a language of its own. As with any artwork or various languages, there are important structures and understanding necessary. Many people do not understand this when they receive their first camera. They simply go about their way glossy eyed snapping shots all over the place. Very few have the understanding of the bigger picture.


One way of viewing this is using a simple analogy. When reading for a bath, you do not overfill the tub, or the water will over flow. This is the exact same as ISO which is a setting that tells your camera how mush lighting is required. (ISO involves both the aperture, shutter speed, and is part of the exposure pyramid). This is discussed further later in this article.

ISO is an important aspect to understand when you are talking about taking high or low-light pictures. A high ISO needs less light whereas a low ISO require more light.

Shutter speed

The first thing we should discuss is shutter speed. As with the tub filling explanation, the longer the tap is left open the more water will fill the tub. This is the same with the shutter speed on your camera. If the shutter is open longer, it allows more light. It is important to note that a long shutter speed will cause blur as opposed to a short shutter, which will be more precise freezing the shot. Many amateur photographers will be shaky and may not have a still hand, using a tripod will correct this problem.


The next thing we need to look at is the aperture. (F-Stop). Aperture in comparison to our bathtub analogy is similar in nature as to how much you open the faucet. Is it wide open providing a large amount of water to flow, or is it barely on, stream-like. If you are on the low end, you will need to use a combination of shutter speed (long) allowing your aperture to change the field depth. The area directly in front of your camera is considered the depth of field and what will be in focus. If you are focused in close on the subject’s face, your depth field is shorter than if you were shooting a large group shot.

Lightning measurement

Interestingly, all of the lighting controls within a camera are measured in unit. The aspect is known as the ‘stop’. This tends to be confusing for new photographers; a stop is either double or one-half the light prior. If your ISO is 100 on your camera and you change it 20 200, you will only need half the light you did on the 100 setting. Or 1 stop less light, at the same time if your shutter speed is 1/125 and you double the speed you would have 1 less stop. ISO stop is the same as an aperture stop (f-stop). If you are good at math this is a rather easy calculation, based on the circumference or area of a circle.

To make it a bit easier to understand I will try to explain it: As we have discussed there are values between 100 and 200 for the ISO, at the same time there shutter speeds go between 1/125 and 1/250. A larger aperture will let in less light than a smaller setting. F4 is much brighter than say F22. Most DSLR cameras these days highest settings F2.8. For full stop apertures, reduced light settings are F4, F5.6, F8, F11 up to F22. Each one provides less light than the one prior does. Or one less stop than the previous one.

Some cameras have metering systems; this provides the photographer with information as to the overall amount of light. The setting is automatic and will choose what it the best aperture, shutter speed depending on the field depth of the subject being shot.