Bridge digital camera

Bridge digital cameras are a type of high-end digital camera. They are comparable in size and weight to the smallest digital single-lens reflex cameras (DSLRs), but they lack the removable lenses, larger sensors, [ [http://www.dpreview.com/learn/?/Glossary/Camera_System/sensor_sizes_01.htm Sensor Sizes: Camera System: Glossary: Learn: Digital Photography Review ] ] mirror, and reflex system that characterize DSLRs. The term "bridge" characterizes the way in which these cameras fill the niche between the DSLRs and the compact digital cameras. Although bridge cameras are closely related to consumer compacts, they are sometimes confused with DSLRs due to their similar bodies and large zoom lenses. Almost all bridge digital cameras feature full manual controls over shutter-speed, aperture, ISO, white-balance and metering. Generally, their feature sets are similar to DSLRs, except for a smaller range of ISO sensitivities due to their smaller sensors (a DSLR has a 35mm, APS, or 4/3 size CCD or CMOS) and less expandability options (such as interchangeable lenses, battery grips, and wireless flash options).

One fixed but versatile lens

Because bridge cameras have small sensors, their lenses can also be smaller than DSLR lenses while providing comparable zoom abilities. 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 newer cameras reach over 500mm. [ [http://www.dpreview.com/news/0707/07072402panasonicfz18.asp Panasonic DMC-FZ18: Digital Photography Review ] ] For this reason, bridge cameras typically fall into the category of "superzoom cameras" [See, for example, http://www.popphoto.com/cameras/2483/editors-choice-2006-superzoom-evf-cameras.html and http://dpreview.com/reviews/panasonicfz50/] . The ability to fit such a wide zoom range in one single small-diameter lens makes lens interchangeability redundant for most photographers. However, 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.

LCDs and EVFs as principal viewfinders

Bridge cameras employ two types of electronic screens as viewfinders: The LCD and the "electronic viewfinder" (EVF). All bridge cameras have an LCD with live-preview and usually in addition either an EVF or an "optical viewfinder" (OVF) (non-parallax-free, as opposed to the OVF of DSLRs, which is parallax-free). The existence of a high-quality EVF is one of the advanced features that distinguish bridge cameras from consumer compact cameras.

Electronic viewfinders (EVFs) vs DSLR reflex viewfinder comparison

Live-preview EVF advantages

Since in bridge camera there is no mirror that blocks the image formed by the objective lens from being projected over the sensor, as is the case with DSLRs, the LCD and EVF of bridge cameras continuously show the image generated by the sensor. This continuous digitally-generated live-preview has some advantages and disadvantages over the optically-generated view through the OVF of DSLRs. One advantage is that the digital preview is affected by all shooting settings and thus the image is seen as it will be recorded (in terms of things like exposure, white balance, grain-noise, etc) which the OVF of DSLRs is incapable of showing [ [http://www.neocamera.com/feature_viewfinders.html Digital Camera Viewfinders: OVF, EVF, LCD, SLR, DSLR, Optical, Electronic, Tunnel | NeoCamera.com ] ] . Another advantage is facilitating the framing from difficult angles by making the LCD movable (vari-angle). Also the LCD and EVF show 100% of the image while previewing (WYSIWYG), while the OVF of some DSLRs (especially entry level DSLRs) does not cover the full 100%.

Live-preview viewfinder disadvantages

The disadvantages however are that the electronic screens of bridge cameras do not work as well as the OVF of DSLRs in situations of low light (or in bright day-light with the LCD), where the screen might be difficult to see and use for framing. Also the screen is of low resolution and refresh rate compared to the very high resolution and instantaneous refresh provided by an optical path in the OVF of DSLRs. This low resolution makes it more difficult to focus manually. However, most modern bridge cameras implement a method that automatically magnifies a central frame within the screen (manual focus point) to allow easier manual focusing. A slow refresh rate means that the image seen on the screen will have a fraction of a second lag or delay from real scene being photographed. The electronic screens used in modern bridge cameras are gradually improving in their size, resolution, visibility, magnification and refresh rate.

Another disadvantage is battery life. A DSLR's sensor is not operating unless the shutter is open, and the electronic screen is typically off more, causing less battery drain.

LCD and EVF of bridge cameras continuously showing the image generated by the sensor causes superheating of the sensor increasing digital noise; in a DSLR, the sensor is exposed to the light only for the time strictly necessary for the shot.

Examples of bridge cameras

Current examples of bridge cameras are the Canon PowerShot S5 IS, Fujifilm FinePix S100fs, Olympus SP-570UZ, and the Panasonic Lumix DMC-FZ50. The upcoming Casio Exilim Pro EX-F1 could also be considered a bridge camera, though its video features distinguish it from any other consumer camera. Kodak also produces a line of super-zoom cameras, though these do not have essential DSLR features such as the ability to use an external flash (with the exception of the EasyShare P-Series). Nikon currently manufactures the Coolpix P80, which is an 18x superzoom, but lacks the external flash capability of other bridge cameras. Minolta (before the Konica Minolta merger) marketed the DiMAGE series, with the Minolta GT manual fixed zoom lens. Their bridge digital cameras were known as ZSLRs (zoom lens, single lens reflex). Olympus was the first to place a 20x zoom on a bridge camera with the Olympus SP-570.

Exceptions

Some cameras may share several bridge camera features, but differ for some significant reason. For example, the Sony DSC-R1 (2005-2006) and the Sigma DP1 (2008) have non-interchangeable lenses and no mirror/reflex systems, but they have APS size imaging sensors. The DP1 is also much smaller than typical bridge cameras, and has a fixed focal length (non-zoom) lens. Digital rangefinders like the Leica M8 and the Epson R-D1 have no mirror/reflex systems, but do have interchangeable lenses and large imaging sensors; while these cameras are not DSLRs, they are very expensive and occupy a very different niche than do bridge cameras.

References