How to control aperture
Manual exposure gives you total control over both aperture and shutter speed, but it can be a fiddly system when you’re just starting out.
Aperture Priority (A or Av) is a semi-automatic exposure mode that, as the name suggests, enables you to set the aperture as a priority.
The easy way to control aperture yourself is by selecting A/Av mode on the Mode dial. Then simply rotate your camera’s main input dial to increase or decrease the aperture setting. The camera will automatically adjust the shutter speed as you do so.
Digital SLRs offer a choice of up to three aperture scales, with full-stop, half-stop or third-stop increments (head to your camera’s Custom Functions menu to choose your preference). We prefer third stops as it enables fine-tuning of exposure.
There are three ways to keep track of the aperture setting – in the viewfinder, on the rear LCD screen and, in the case of high-end DSLRs, on the small top-plate LCD screen. We like the clarity that a top screen and the viewfinder provide.
Many cameras have a Depth of Field Preview button that closes the aperture down to the setting you’ve chosen, enabling you to gauge the depth of field through the viewfinder. However, Live View offers a more effective representation of the aperture setting.
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