In some shooting environments, flash photography is strictly prohibited. Often, the ambient light is so poor that the shutter speed becomes very low. In this situation, the photo can be easily affected by blurs caused by camera shakes and subject movement.
If you are handholding a lens, the rule of thumb says you typically need 1/f (f is the focal length in millimeter) second of shutter speed. For example, if you are shooting with a 200mm lens handheld, you need about 1/200s or faster shutter speed to avoid most of the camera shake. This is for average people. Some one may have very steady hands, others may have especially shaky ones. If you have a lens with vibration reduction (VR), image stabilization (IS), or vibration cancellation (VC) functions, the speed requirement can be greatly relaxed. Often, you can shoot with up to 4 stops (or 16 times) slower shutter speed. Read More…
