Shooting in Auto mode is simple as a good camera will automatically select the optimal settings. However, sometimes there comes a time when photographers will want to control the amount of light coming into the camera – that’s when the Aperture-Priority Mode comes into play.
Most commonly marked as AV or A on the camera mode dials, Aperture-Priority Mode is a semi-automatic mode that allows the photographer to manually set the F values (which are used to identify aperture size) to control the depth of field – the larger the aperture, the shallower the depth of field. The mode is considered to be semi-automatic because the camera will then automatically select the most appropriate shutter speed to achieve the proper exposure.
This mode can be useful in a number of ways but essentially it allows you to control the amount of background blur – or ‘bokeh’ as the professionals refer to it. Since the Aperture-Priority Mode is responsible for the amount of light coming in through the lens, it can be very helpful in low light situations when the shutter speed is limited because of the subject or the camera movement.
In Aperture-Priority Mode the F-values (sometimes called f-stop, focal ratio, f-ratio, or relative aperture) are limited by the lens that is attached to the camera. Here is the general rule of thumb – the larger the aperture or the smaller the f/stop number, the shorter the depth of field. Typically, lenses with large aperture (and small F-value) will be more expansive then lenses that cannot go as wide.
That’s all nice and swell, but can Aperture-Priority Mode make you a better photographer? It actually can be useful in many applications:
- In portrait photography, you can use wide aperture to throw the background out of focus and focus directly on the subject. (Interestingly enough, some lenses that allow really wide aperture (F/1.2) at close range might blur out the subject’s eyes while keeping the nose in focus. Just something to keep in mind.)
- In landscape photography small aperture brings everything in focus and produces a sharp detail throughout the image (For example: in F/22 that tree in front and that mountain in the back will all be in perfect focus).
- In macro photography it is important to know that the closer your subject is to the camera, the narrower your depth of field becomes. If you are just an inch away from object A and object B is an inch further, the wide aperture would cause object B to be completely out of focus. In macro photography, the depth of field would not be bigger than an inch or so.
If you are new Aperture-Priority Mode (and/or if this is a bit confusing) – I would encourage you to try and experiment. Just set your camera to AV or A mode and take a few pictures of the same subject using different F-values. For consistent results, I would advise to use a tripod. Choose one subject and focus the camera on it. Snap several pictures ranging from wide to small aperture depending on what your lens allows. Then compare the results and see for yourself how much difference Aperture-Priority Mode makes.