To explain aperture simply, I will use an example of a cave.
You are walking along outside the deserted caves of Egypt and you come across an opening to something new. The sun is at your back. The opening is so low you crawl in on your knees then stand up inside. What can you see?
You crawl out and walk a little farther down and come across a big opening to the same cave, you can walk in. What do you see?
Think of aperture as a hole. The hole is given a name. F. F for Focal. The hole comes in different sizes. So the hole let’s in different amounts of light. The bigger the hole. You get my meaning.
However, if I was to say to you what is bigger a 50cm X 50cm box, or a 1.4cm x 1.4cm box what would you say?
Well with aperture small is big. Take a gander at this sample.
So you want to get a lens with a big hole to let in more light, to take better pictures in low light situations. Well Lenses come in different shapes and sizes, some are zoom and some are Prime.
Prime lenses have a low aperture number, like 50mm 1.8 or 1.4. The 1.4 will obviously let in a little bit more light, because when you press the shutter for the eye to open, to let in the light on the censor, it can understand more of the object you want to Photograph. This is also called a fixed lens.
Zoom lenses only go down to a set aperture but they can go up and down in relation to the magnification of your object. 18mm to 55mm for example. A prime lens can’t zoom in closer. Zoom lenses now come with image stabilisation and this can really help if object is stationary in low light.
Street photographers must understand what their camera and lens can do with light. My advice is to go with a prime lens and although I always use a 35mm, the 50mm is better to start off with and better for portraits of interesting people. A good Prime lens can last you a lifetime if you look after it.