Aperture

Do you know what aperture is? It is actually the size of the opening in the lens, measure in f-number to control the amount of light entering the lens. The aperture also affects the depth of field.

To really have control over your camera, you must learn how to control the aperture. The aperture could do wonders to your photo and give it the extra 'power'. I bet you all have seen photos where the front subject is very clear and the background is being blurred off. This is where the magic of aperture sets in.

Aperture is actually measured based on f-numbers or f/stops. For example: f1.8, f2.0, f2.8, f4, f5.6 and so on. Moving from one f-number to the left (smaller number) doubles the opening of the lens and if moved to the right (bigger number), the amount of opening in your lens (the amount of light getting through) will be halved. Another example to make you clearer: f2 allows twice as much light than f2.8. f2.8 has half as much light as f2 but twice as much light as f4 etc.

F2.8

F3.5

F4

F5.6

F6.7

Did you see that the picture shown above is getting darker and darker? This is because the aperture is becoming smaller and smaller while the other settings are fixed. That is why you will notice that less light is entering the lens. (taken at shutter speed: 1/30 and ISO: 1600)

The aperture value being set controls the size of the hole of the lens. As you know the larger the hole, the more lights get it and vice versa. To have a larger opening of the lens (more light entering), you will need a smaller f-number and to have a smaller opening (less light entering), a larger f-number is needed. When photographers say increase in aperture, they mean by getting a smaller f-number (bigger 'hole' in the lens) and vice versa.

Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light passing through the lens. This means if you increase your shutter speed make sure you increase your aperture too if you do not want your picture to be underexposed.

The aperture is also able to create the effect that I mentioned earlier which is the front subject is clear and the background is blurred off. This effect is called "bokeh" and is also associated with depth of field which will be discussed here.