Manage exposure
Adapt your technique for stills photography to correctly expose video clips
If there is one area that will confuse photographers who are starting their video journey, it is exposure. As any experienced photographer will know, if the scene is too bright it is overexposed and so must be corrected using the three exposure components – shutter speed, aperture and ISO, or a combination of these. While the exposure of a video clip is exactly the same in a physical sense, practically speaking there are some inherent differences in how this is applied while shooting.
Firstly, it is generally considered good practice to lock the exposure before filming begins – while not necessarily critical in all circumstances, a change in brightness within a clip is distracting and creates an amateurish look. This means careful exposure choices before recording begins. Furthermore the exact choice of shutter speed is more restricted than in stills photography. In low light it isn’t always possible to raise the ISO as high when shooting video, as a moving noise pattern is difficult to hide. This means that aperture and shutter speed alone must be used in such conditions.
Then there is the matter of image style. While a slower shutter speed can be used to create a tripod-based long exposure in photography, with a moving image a blurred effect is not as viable for many subjects. Widely speaking, a shutter speed of 1/50sec can be considered the lowest setting for everyday purposes, as longer exposures than this will introduce an obvious motion blur, for both moving objects in the frame and of camera motion itself.
At the other end of the scale, it can be a challenge to achieve shallow-depth-of-field, as there are disadvantages to selecting a fast shutter speed. 1/200sec will freeze every frame, producing a choppy, unnaturally sharp look which can be unsettling to the viewer if used incorrectly. In daylight conditions therefore, even at the lowest ISO, using a wide aperture can easily result in overexposure, since we can’t simply select a shorter exposure duration.
All of these differences may be overwhelming at first, but here we explore the truth behind the ‘rules’ of videography.