Ok, so the last blog i posted, i wrote about how your exposure effects your image. There are 3 main things that will effect your exposure.. these are your Aperture, Shutter Speed and your ISO.

To make this blog NOT be 10 pages long, i'm just gonna go into detail in this one about your aperture. Again, i'm sure this is nothing new to many people, but hopefully it'll help bring clarity if you need it on this topic!

An aperture is a hole or opening through which light is admitted. The aperture stops in a photographoc lens, can be adjusted to control the amount of light that reaches the digital sensor or film in the camera. In combination with the shutter speed, the aperture regulates the film’s degree of exposure to light.

If I want more light in my photo, I can choose to open the aperture wider and if I want less light, I can choose for it to open smaller. The diameter of the aperture is measured in f-stops. It took me while to get used to the fact that the lower the F number, the wider the aperature opens and the higher the F stop, the smaller the aperature opens, letting in less light.

The size of the aperture is one factor that effects depth of field. Smaller stops produce longer DOF, allowing objects at a wide range of distances to all be in focus at the same time. If I want to throw the background out of focus, I use a larger aperture e.g. F4 or F8.

While we are talking about aperture settings, it is good to know about shooting in aperture priority mode. This is a semi automatic mode. It allows me to choose the aperture setting and the camera automatically sets the shutter speed for correct exposure. This is sometimes referred to as Aperture Priority Auto Exposure, A mode, Av mode, or semi-auto mode.

When looking at lenses, they include the minimum and maximum apertures.
This refers to the minimum and maximum size the aperture can open to. A typical lens may have aperture sizes ranging from F2 to F16, but this obviously depends on the lens and what it’s primary function is.

The maximum aperture (minimum F number) tends to be of most interest and is always included when describing a lens.
According to wikipedia, the largest aperture used in film history, was F0.7 and was used in Stanley Kubrick’s film Barry Lyndon.

Prime lenses (non zoon lenses) have a fixed focal length (FFL) and a large aperture. These are favoured by professionals, especially the likes of photojournalists who may be working in bad lighting situations and have to be able to capture good photos no matter what the lighting conditions.

Zoom lenses typically will have apertures around the ranges of F2.8 to F6.3. A very fast and expensive zoom lens will have a constant aperture of F2.8 or F2. This means that the aperture will stay the same size through the zoom range.


Experiment with your aperture. Take photos starting with the largest aperture, and then go to the smallest. If you are shooting on manual, it will give you a good idea of the effect your aperture has on your pics.

Happy Shooting over the Halloween weekend... i'll explain ISO and Shutter Speed in my next blogs!

Rebecca