What is aperture, and how does it affect my photographs?

Question

How does aperture affect my photographs?

Why should I care about the aperture with which a photo was taken?

Answer

The aperture affects not only the amount of time required to take a photo, but also the depth of field within it.

With a wide aperture (so a low number, like f/1.8) gives a shallow depth of field - sometimes less than a millimetre with a macro lens. Because a lot of light is reaching the sensor (be it film or digital), this allows for fast shutter speeds

With a narrow aperture (so a high number like f/22), the depth of field is much greater, which is useful for things like landscape photography - it will limit the amount of light reaching your sensor, so you will get slower shutter speeds, which makes a tripod handy.

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