What is Exposure?

One of the most important thing that you need to understand about photography is exposure. Exposure represents the correct amount of light required to correctly capture the scene. Photography, by definition is actually the act of capturing light onto film, but in the digital age, onto your light sensor instead :P

I know it is a little hard to visualise, how do we measure how much light is required for the particular scene. So to makes thing a little simpler for you, can you visualise a cup of water instead?

To have a correctly exposed shot, it is the same as making the perfect cup of coffee. First, you'll need to have 250ml of water. Too much and it will be too diluted, too little and your coffee will be too thick.

Just like photography, if you have too much light, your picture would be overexposed, and if you have too little light, it will be underexposed.

The photo above, shows a correctly exposed (left photo) shot of a milk carton. The underexposed shot (right top photo) looks a little too dark, while the overexposed shot (right bottom photo) looks too bright, till details of the carton are loss.

So, how do we control how much light is required. All cameras have the ability to control the amount of light, either through the shutter speed or the aperture. Aperture basically controls how much is allowed onto your sensor, while shutter speed controls the time the aperture is kept opened.

Think of it like controlling your water tap. If you keep your tap open longer (longer shutter), you'll have more water through. Either that or, if you have bigger tap head/pipe (big aperture) you'll get more water in the same amount of time.


The photo above, shows a lens with its aperture set. As you can see, in the first photo, it has the aperture wide open, allowing the maximum light through, while the second photo, shows only a tiny hole, thus allowing minimal light through.