Choosing an Exposure Mode : Aperture Priority and Shutter Priority

Today’s most of the DSLR camera has dedicated scene modes like close-up, portrait, sports etc which set exposure for you automatically and few exposure modes to allow control over your camera default settings. You really do not have control over exposure on those automatic (scene) modes. But if you really want to set exposure as per your need, you have to use one of the four modes (Aperture Priority, Shutter Priority, Program Mode and Manual Exposure) available with your camera. Three of them are semi-automated modes and one is manual mode. All these modes have their one principle and uses. You have to rotate Mode Dial to change between different modes. These settings are not specific to camera model but different company may use different alphabet to denote these features. But to make everything simple and smooth, I will take Nikon D90 as a reference to explain these modes. I will discuss first two modes in this post and last two in my next post.

1. Aperture Priority

In Aperture Priority ( A ) mode, you set aperture value or give priority to aperture value and your camera, D90, sets the shutter speed to control exposure. This mode is probably best when you want to control opening or closing of your lens to gain shallow or deep depth of field. You have to use smallest F-stop (f/stop) value to get shallow depth of field in a close-up picture like flowers or portraits. And you might want to use large f/stop value to get everything in focus for e.g. landscape shooting.

This mode is best if you want to lock aperture at some value and you want your camera to set shutter speed according to aperture value you set. If your current aperture value and shutter speed doesn’t match to give optimal exposure for your subject, you will get Lo or HI indicator in the viewfinder telling you that subject is too dark or too bright resulting underexposed or overexposed photograph. You might want to consider your setting at that point.

2. Shutter Priority

Shutter Priority ( S ) mode is just an opposite of Aperture Priority mode. In this mode, you set shutter speed and your camera will adjust aperture value for that shutter speed. You might want to use this mode when you want to shoot fast moving objects to freeze the motion (shooting sports events) or you want to make your shutter speed slower so that you can get more light with proper combination of aperture value.

Please continue to read about Program Mode and Manual Exposure Mode.

Related posts

1. Choosing an Exposure Mode : Program Mode and Manual Exposure Mode
2. Choosing a Flash Sync Mode on Nikon D90
3. Choosing a Release Mode on Nikon D7000
4. Understanding Aperture and Depth of Field
5. Fundamentals of Shutter Speed

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