The impact of aperture and ISO

If you set a shorter shutter speed, less light gets to the digital sensor on your camera and the image will be underexposed. To compensate you need a wider lens aperture and/or a higher ISO speed setting.

A lens with a wide maximum aperture allows you to set a faster shutter speed and expose correctly. Many prime lenses (non-zoom) available for Canon EOS cameras have maximum apertures of f/2.8 or wider and are popular with sports photographers. Learn more about Canon lenses at the new Canon lens site.

If you don’t have one of these lenses you can set a higher ISO value, making the sensor more sensitive to light. The downside to this can be an increase in ‘noise’ – coloured speckles across the image. The latest Canon compact digital cameras feature the HS System which lowers noise levels by up to 60%. Discover more about the HS System.

Panning your camera
It is possible to obtain quite a sharp image of a moving subject even at slow shutter speeds. This is done by ‘panning’ the camera; move the camera so that the subject remains in the same position on the sensor during the exposure. It works best with a subject moving at a constant speed in one direction, such as a bird in flight or a car on a racetrack.

 

A good pan shot reverses the normal situation – the subject is sharp, but the background is blurred. Some subjects can be sharp and blurred at the same time. The body of a bird in flight, for example, will be sharp, but the wings moving up and down at right angles to the movement of the camera will be blurred. It is important to find the right position for panning; your subject should be the same distance from you throughout your shot.

Good panning takes practice and more practice. One trick is to keep panning after pressing the shutter release, so that the pan becomes a smooth movement.

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