A lens shutter camera is a camera in which the shutter mechanism is built directly into the lens assembly rather than being located in the camera body immediately in front of the film or sensor plane as in a focal plane shutter camera. The shutter in such a camera is typically a leaf shutter, consisting of a series of thin overlapping metal blades positioned within the lens barrel near the optical centre of the lens elements, which open and close to control the duration of the exposure.
The integration of the shutter into the lens rather than the camera body has a number of important practical and optical consequences that distinguish lens shutter cameras from their focal plane shutter counterparts. Most significantly, because the leaf shutter within the lens opens and closes as a complete unit, fully uncovering the entire image area simultaneously at every shutter speed, lens shutter cameras are capable of synchronising with electronic flash at all available shutter speeds without restriction. This unrestricted flash synchronisation is one of the most valued practical advantages of the lens shutter design, making lens shutter cameras particularly well suited to outdoor portrait, wedding, and commercial photography where flash is used in combination with bright ambient daylight and fast shutter speeds are needed to balance the two light sources effectively.
Lens shutter cameras encompass a broad range of camera types, from simple fixed lens compact cameras and rangefinder cameras through to professional medium and large format technical cameras whose interchangeable lenses each contain their own individual shutter. In medium and large format photography, where lens shutters are the standard arrangement, each lens in the system must be purchased with its own built in shutter, which adds to the cost and complexity of the system but provides the flash synchronisation and operational advantages associated with the between-lens shutter design.
The principal limitations of lens shutter cameras compared to focal plane shutter designs include the generally lower maximum shutter speeds achievable - typically up to 1/500th of a second compared to 1/4000th or faster on modern focal plane shutter cameras - and the added cost and complexity of incorporating a shutter mechanism into every interchangeable lens in the system. Nevertheless, for the specific applications where unrestricted flash synchronisation is a priority, the lens shutter camera remains a highly practical and valued tool.