Semi-Auto Mode Camera: Creative Control, Simplified

Semi-automatic camera modes are settings that give the photographer control over some aspects of their camera settings while the camera automatically adjusts the others. The three main settings that determine a photo's exposure are shutter speed, aperture, and ISO. In full auto mode, the camera chooses all three settings, whereas in full manual mode, the photographer must adjust all three. Semi-automatic modes allow the photographer to choose one or two of these settings and leave the camera to automatically adjust the rest. The three semi-automatic modes are shutter priority, aperture priority, and program mode.

Semi-auto mode explained

Semi-auto mode is a setting on your camera that allows you to have more control over your photographs than you would with a full auto mode, but without having to make all the adjustments yourself, as you would in manual mode.

How Exposure Works

Three of the most important settings for photography are shutter speed, aperture, and ISO. These settings work together to control the exposure of your photograph, and are known as the exposure triangle.

In full auto mode, you can't adjust any of these settings. In full manual mode, you have to adjust all three. Semi-auto mode sits somewhere in between, allowing you to control some of these settings while the camera automatically adjusts the others.

Semi-Auto Modes

The three most common semi-auto modes are shutter priority, aperture priority, and program mode.

Shutter Priority

In shutter priority mode, you select the shutter speed, and the camera automatically adjusts the aperture to give you the correct exposure. This mode is useful when you want to freeze movement or create motion blur.

Aperture Priority

In aperture priority mode, you select the aperture, and the camera automatically adjusts the shutter speed. This mode is useful when you want to control the depth of field in your photograph.

Program Mode

In program mode, the camera automatically selects both the aperture and shutter speed, but you can cycle through different combinations of these settings if you don't like the initial suggestion. This mode is less commonly used by professional photographers, as both shutter speed and aperture will shift as the lighting changes, and you will need to constantly monitor these settings.

When to Use Semi-Auto Mode

Semi-auto mode is useful when you are constantly referring to your meter from shot to shot, and it generally seems accurate. It can be particularly useful for landscape photography, wildlife photography, and situations where the lighting is changing quickly.

When to Use Manual Mode

Manual mode is best used when you need consistency in your photographs. For example, if you are photographing a bride under constant lighting and want her face to remain the same brightness regardless of the background, or if you are taking a panorama where each photograph needs to have the same exposure.

Aperture Priority Mode

Aperture priority is one of the most useful camera modes as it gives the photographer full control over the aperture setting, which is considered the single most important setting in photography. It is also faster to use than manual mode and can be used in changing light conditions.

To use aperture priority mode, the photographer must first enter the mode by turning the PASM dial to "A" or "Av". They then manually select their desired aperture, or f-stop, which will not be changed by the camera. The photographer can then select the proper exposure compensation and ISO value.

Shutter Priority Mode

In Shutter Priority mode, the photographer sets the shutter speed of their camera, and the camera then sets the aperture that complements this speed to ensure the image is well-exposed. The faster the shutter speed, the less light will reach the camera's sensor, resulting in a darker image. Conversely, a slower shutter speed will allow more light to reach the sensor, resulting in a brighter image.

To set Shutter Priority mode, the camera dial is usually turned to "S" or "Tv" for "Time Value". The photographer then chooses their desired shutter speed, and can also set an ISO value.

Program Mode

In Program mode, you can control the ISO, while the camera controls the shutter speed and aperture. ISO amplifies brightness and decreases image quality. A low ISO will give you better-quality photos, but less light sensitivity. A high ISO will brighten your photos but also add noise or digital grain to the image.

Some cameras also provide additional control in Program mode, such as the ability to adjust shutter speed or aperture. This can be particularly useful when you want to control the depth of field or freeze or blur the movement of your subject.

To use Program mode, turn the camera mode dial to "P". Then, test the exposure and use exposure compensation to adjust the image if it is too light or too dark. Set your ISO based on the light available, and frame and focus your shot. You can then adjust the auto settings using the control dial until you find the right combination of aperture and shutter speed. Finally, take your shot.

Manual Mode

However, you don't need to use manual mode all the time. Semi-automatic modes can be the quickest option available without sacrificing any control over your settings.

Frequently asked questions