Definition: Central shutter

Definition: Central shutter | Glossary entry

Central shutter

The central shutter is not a type of shutter. It is a term that defines the location of the shutter.

DSLR shutters

Most DSLRs have a focal plane shutter which is located just in front of the sensor plane (or focal plane, or image plane). It makes sense not to have a shutter in an interchangeable lens (photographic lens) like those used on a DSLR because it is an extra component to build in to each one. This would raise the cost and the weight of the lens. A central shutter could be located just behind the lens in a DSLR and there are some models with this configuration, but it is unusual.

The shutter in a full frame DSLR is relatively slow since it has to open to cover a large sensor. In fact most DSLRs have a limit on the flash exposure time (flash synchronisation speed) because the shutter is slow to operate over a big gap.

Fixed lens camera shutters

Fixed lens cameras do have shutters built into them. In this case it enables the shutter components to be smaller and more compact which can increase their speed and control. Point and shoot cameras, bridge cameras and fixed lens compact cameras may all have a central shutter.

The following advantages are gained by a central shutter:

  • Simple construction
  • Cheaper (because simpler and smaller)
  • Small size (located in the smallest cross-section light traverses)
  • Less components
  • Faster shutter speeds (because smaller size and area to shutter off)
  • It’s possible to design a smaller body when the shutter is in the lens
Medium and large format cameras

Because the film or digital backs of these cameras are so large the shutter would be too slow to open or close to allow fast exposures. As a result these cameras tend to have central shutters in the lenses where they can be built smaller and will respond faster. This does raise the cost of the lenses and may shorten the life of the lens.

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By Damon Guy (author and Photokonnexion editor)

Damon Guy - Netkonnexion

Damon Guy (Netkonnexion)

Damon is a writer-photog and editor of this site. He has run some major websites, a computing department and a digital image library. He started out as a trained teacher and now runs training for digital photographers.
See also: Editors ‘Bio’.