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Bridge cameras are cameras that fill the niche between the single-lens reflex cameras (SLRs) and the point-and-shoot camera. They are often comparable in size and weight to the smallest digital SLRs (DSLR) and there are also superzoom DSLR-shape bridge camera with retractable lens to make it more compact,〔(【引用サイトリンク】title=Fuji Unveils New Cameras at CES 2014 )〕 but almost all digital bridge cameras lack an optical viewfinder system (film bridges generally had a lighter version of a reflex finder). In addition, SLRs normally feature interchangeable lenses, while current bridge cameras do not. They are prominent in the prosumer market segment. The phrase has been in use at least since the 1980s,〔 and continues to be used with digital cameras.〔 The term "bridge camera" was originally used to refer to film cameras which "bridged the gap" between point-and-shoot cameras and SLRs. Like other cameras, most current bridge cameras are digital. These cameras typically feature full manual controls over shutter speed, aperture, ISO sensitivity, color balance and metering. Generally, their feature sets are similar to consumer DSLRs, except for a smaller range of ISO sensitivity because of their typically smaller image sensor (a DSLR has a 35mm, APS, or Four Thirds size CCD or CMOS sensor). Many bridge cameras have long zoom lenses which now often start at a super wide-angle focal length of 20 or 22mm equivalent focal length (in 35mm film camera terms), so the term "bridge camera" is often used interchangeably with "megazoom", "superzoom", or "ultrazoom."〔(【引用サイトリンク】title=Pentax XG-1 announced: Ricoh turns the ultrazoom bridge camera up to 11 with a 52x zoom lens )〕 However, some bridge cameras have only moderate or short zooms (such as the Canon Powershot G9), while many compact cameras have superzoom lenses but lack the advanced functions of a bridge camera. With zoom ranges and sales rapidly increasing in the early 21st century, every major camera manufacturer has at least one 'super zoom' in their lineup. Sales of bridge cameras with DSLR-shape and MILC are steady in the overall context of declining camera sales. == One fixed but versatile lens == Bridge cameras typically have small image sensors, allowing their lenses also to be smaller than a 35mm or APS-C SLR lens covering the same zoom range. As a result, very large zoom ranges (from wide-angle to telephoto, including macro) are feasible with one lens. The typical bridge camera has a telephoto zoom limit of over 400mm (35mm equivalent), although some 21st-century cameras reach up to 2000mm.〔(【引用サイトリンク】title=Nikon P900 vs Sony HX400 Comparison )〕 For this reason, bridge cameras typically fall into the category of ''superzoom cameras''. A typical example is the 24× Zoom Nikkor ED 4.6-110.4mm f2.8-5.0 on the Nikon Coolpix P90, which in 35 mm equivalent focal length terms is a 26-624mm. To reduce aberration in a lens with such ambitious specifications, these have quite complex constructions, using multiple aspheric elements and often anomalous-dispersion glass. In this example pincushion and barrel distortion can be corrected in the camera firmware as well. The ability to fit such a wide zoom range in one single small-diameter lens makes lens interchangeability for the purposes of focal length (as opposed to performance in low light or image quality) redundant for most photographers. Most bridge cameras allow the use of secondary lenses to improve wide-angle, telephoto or macro capabilities. These secondary lenses typically screw onto the front of the primary lens either directly or by use of an adapter tube. Superzooms have typically had a large f-number (aperture) especially at the long end. The resulting depth of field prevents the use of shallow field methods, and prevents photography in low light without the use of either flash or a tripod. Several recent models, however, offer apertures as wide as f/2.8 at the long end. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「bridge camera」の詳細全文を読む スポンサード リンク
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