Take control of shutter speed
Control motion blur by working in Shutter Priority
If you work in Aperture Priority (Av) mode, the camera will set a shutter speed to give a balanced exposure with the aperture you’ve selected. When light levels are low, or you have set a small aperture, the shutter speed can become too slow to take sharp handheld shots – something that’s easy to miss when you’re concentrating on composing a shot.
Working in Shutter Priority (Tv) or Manual mode enable you to set a specific shutter speed, so you can be sure that it’s appropriate for the conditions you’re working with. The rule of thumb for working out what the shutter speed needs to be to avoid blur caused by camera shake, is to base it on the effective focal length of the lens – the ‘1/mm’ rule. This needs to take into account the crop factor of the camera’s sensor.
For example, a 50mm lens attached to a full-frame camera, such as the EOS 6D Mark II, should give sharp handheld pictures at 1/50 sec. But with the same lens attached to a EOS 7D Mark II, which has a smaller APS-C sensor with a crop factor of x1.6, you should aim for a shutter speed of at least 1/80 sec (50x1.6). Your mileage may vary, however, as some cameras and lenses are more cumbersome than others.
Of course, there will be times when you want to use a slow shutter speed to make moving parts of scene appear blurred. For that, you’ll need to use a tripod or similar support to keep the camera motionless and allow the stationary elements of the picture to be rendered sharp. The contrast between the stationary features and the moving ones can actually heighten the impression of sharpness.