Understanding exposure in photography – Canon

[EXPOSURE: LEARN FROM THE PROFESSIONALS] Exposure is made of three factors:
aperture, shutter speed and ISO. They are intrinsically linked, and you cannot alter one
without considering the other two. The aperture
determines the amount of light passing through the camera lens. It also controls the depth of field. A wide aperture
lets a lot of light through, and creates a shallow depth of field. Only a single point in the foreground, where I’ve focussed
the camera, is sharp. I’m going to take a second picture. It’s exactly the same
composition, the same focal point, but I’m going to use
a smaller aperture. This will massively
increase the depth of field, so that everything, from the
foreground to the background, is sharp. There’s another
small set of rapids here. It’s going to be a great place
to try some shutter speed effects. Shutter speed controls how long
the camera is exposed to the light for. I’m going to set the
camera to Shutter Speed Priority. With my first shot, I’m going
to use a really fast shutter speed, to try and freeze
the motion of the water. In my second shot, I’m going
to use a much slower shutter speed. As the light has longer
to come into the camera, the water and all the movement
turns into a milky glass effect. This vantage point offers a
great overview of the entire gorge. Ahead of me it’s quite well lit,
and to the left of me it’s quite shady. But I want to maintain
the same aperture and shutter speed for
both sides, and do it hand-held. To do that, I need to increase the ISO. ISO is a measurement of the
sensitivity of a camera to light. I’m going to take my first picture. Now, in order to shoot this
darker area on the same settings, I’m going to increase the ISO first. Do be careful though; increasing your ISO too
much can reduce image quality.

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