Why lens shutters in the first place? Part 1 In photography, there are two well-established shutter systems for light dosage. One is the focal-plane shutter which enables very short shutter speeds, and the other is the lens shutter. Apart from focal-plane shutter speeds of 1/12,000 s and shorter, there is a number of reasons which speak for the use of lens shutters. From a theoretical point of view, the lens shutter seemed to be the ideal solution right from the outset. This shutter is usually located where optical conditions are best – between the lens elements and very close to the diaphragm through which the entire incident light enters the camera. Another advantage of this shutter is that it has a radially symmetric opening which prevents the geometric distortion of moving objects. Considering the present state of the art, these properties are no longer of key importance. However, this shutter provides a number of practical benefits which you should take into account when choosing a lens. This applies in particular to flash synchronization which will be discussed on the following page.