Exposure

Image by tanakawho via Flickr

Exposure seems to be the best place to start when looking at how to take great pictures.

Exposure is the amount of light that reaches the camera’s sensor and is controlled by three elements:

1. ISO - the sensitivity to light
2. Aperture - the size of the opening in the lens
3. Shutter speed - the amount op time that the shutter stays open for

They fit together in a triangle so changing one of the three elements will affect the exposure.

The best way I’ve seen this described is as a window.

The bigger the window (aperture) the more light is let into the room (the photo). The window has blinds - and you can change the amount of light by opening and closing the blinds at different speeds (shutter speed). You can change your sensitivity to the light by putting on a pair of sunglasses (ISO).

My camera allows me to control the ISO and the aperture (Av) or the ISO and the shutter speed (Tv) - when using either of these settings the camera controls the third point for me. Alternatively I can use M to control all three points of the triangle myself.

I’ll look at ISO, aperture and shutter speeds in separate posts.

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