One of the wonderful things about modern digital cameras (DSLR / mirrorless) is that they offer many high-tech auto options to capture great images on the fly. The flipside is the confusion that comes with choosing the right option for the shot. These settings on your camera are referred to as “exposure modes” or “metering modes”, and help the computer inside your camera to strive for the best balance between the light and dark areas in the scene you want to capture. Marette Bennett from Refined Edges Wildlife Photography and Training explains the basic exposure mode options and what they do.
Full Auto mode
This mode is nothing more than point and shoot and hope for the best. The camera calculates everything needed to take a photograph. It sets the shutter speed, aperture (depth of field), ISO (light sensitivity), white balance, metering and picture style. If it thinks you need more light, the camera will fire the flash automatically. You don’t have control over your focus points either, which makes this mode quite limited. The only reason to switch to Full Auto Mode is when handing the camera to a nonphotographer to take a picture.
Programme Mode / Programmed Auto (P)
This mode offers a bit of the best of both worlds and is a good place for beginners who wish to get off Full Auto Mode to start. Here the camera sets the shutter speed and aperture automatically from the metering information it receives, and the user sets the ISO (light sensitivity). You also gain control over the camera’s focus points, focus modes, picture styles, white balance and metering modes when using Programme Mode. Additionally, you will have exposure compensation available to further assist in getting the exposure you want. The camera will not automatically fire the flash as in Full Auto Mode. Some tutors and phototgraphers refer to the Programme Mode as ISO Priority Mode since it allows you to decide what the ISO (light sensitivity) should be. You can also choose to set the ISO on auto to further assist you in getting the correct exposure, leaving you to concentrate on composing and framing the shot. This mode is ideal for beginners and indoor/low light photography where you want to achieve a natural-looking scene without firing a flash.
Making use of only the ambient light from a veranda light, this bushbaby was perfectly captured in Programme Mode after the manual or shutter priority modes did not give the desired effect (Shutter: 1/15s | Aperture: F/5.6 | ISO-10000).
Aperture Priority Mode (Nikon: A / Canon: A)
The camera calculates the appropriate shutter speed depending on the aperture or depth of field you have chosen for your shot. As you increase or decrease the depth of field (higher or lower f/stop numbers), you will get a slower or higher shutter speed to compensate for the decreased or increased amount of light coming through the chosen lens opening. In this mode you still set the ISO according to the light available or set the ISO to auto. This matching works well for most scenes, ranging from wildlife to landscapes. This mode is ideal for photographing a specific depth of field for a specific scene or you can try photographing at the optimum sharpness for a specific lens, such as landscapes with a wide-open depth of field, stationary or slow-moving wildlife/people portraits with a shallow field of depth. The trick is to take an image at a certain aperture to get the desired background to support the story you’re telling with your image:
Include the background to create a sense of place (Shutter: 1/500s | Aperture: F/9 | ISO-800)
Blurred background to optimise the subject’s detail (Shutter: 1/640s | Aperture: F/6.3 | ISO-2000)
Eliminate the background to highlight the subject (Shutter: 1/500s | Aperture: F/4.2 | ISO-800)
Taking an image at the lens’ optimum sharpness to optimise the detail of the main subject (Shutter: 1/500s | Aperture: F/6/3 | ISO-2500)
Manual mode (M)
When all the other modes fail to get the image you envision, it’s back to basics in Manual Mode. You will have complete control over every aspect of the exposure, and you need to understand the exposure triangle. You need to set the shutter speed, aperture and ISO. This mode is ideal when, for instance, you want to freeze the action of a bird in flight with a fast shutter speed and also blur the background with a shallow depth of field. Or the opposite, when you want to capture the motion of a waterfall with a slow shutter speed, and you want the fore- and background in perfect focus with a wide depth of field. In both scenarios, you have to set the ISO appropriate to the light available to get the exposure you want.
When shooting in manual mode, you have full control of the image and outcome and by tweaking certain settings you can achieve completely different images featuring the same subject. In the image above, the photographer froze the motion with a fast shutter speed of 1/500s and a lower aperture at F/9; while the bottom shot blurs the motion with a slow shutter speed of 1/30 and high aperture set at F/22. In both shots the ISO was set at 100.
Shutter Priority Mode (Nikon: S / Canon: Tv)
This is the opposite of Aperture Priority Mode, with the camera calculating the aperture depending on the shutter speed you have chosen for your shot. This allows you to increase or decrease the duration the shutter stays open. You can freeze movement by setting a fast shutter speed or create motion blur by setting a slow shutter speed. Again you have to set the ISO (light sensitivity) or set it to auto. Shutter Priority Mode is ideal for action photography where freezing or blurring the subject is the determining factor – this includes birds in flight, fast-moving wildlife, sports, children playing, etc.
Knowing how to use your camera’s shutter priority allows you to freeze the action, as was the case with this image of a Cape Gannet captured in Lambert’s Bay (Shutter: 1/5000s | Aperture: F/6.3 | ISO-800).