Live-preview digital camera
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A live-preview digital camera (LPD) or more precisely, conventionally-generated live-preview digital camera (CGLPD) is a camera that uses a conventionally generated digital image (live-preview) on an electronic screen as its principle means of framing and previewing before taking the photograph. Conventionally-generated means that it is generated by means of continuously and directly projecting the image formed by the objective lens over the main sensor, which in turn feeds the electronic screen with the live-preview. The electronic screen can be either a liquid crystal display (LCD ) or an electronic viewfinder (EVF). With the exception of very few dSLRs with unconventional live-preview, any digital camera that has live-preview falls in this category. Pay special attention to the LPD section in the Digital camera article mentioned above.
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[edit] Historical background
While other types of digital cameras trace back their origin to a corresponding type of film still cameras (for example digital single-lens reflex cameras "dSLRs" to film single-lens reflex cameras "SLRs"; digital rangefinders to film rangefinders...etc); LPDs trace back their origin to electonic (video) TV cameras dating back to as early as the 1940's or 1950's, and took decades to evolve in slow steps to what we have today (consumer LPDs since the mid 1990's). The evolution was so slow and gradual, that it is difficult to decide which step exactly was the beginning of LPDs (which are now considered perfectly capable of taking stills while evolving originally from a movie- or video-type ancestor, with the Sony Mavica released in 1981, as probably the most ambiguously intermediate form).
[edit] A well-known but unnamed category
LPD is the type of camera that comes in mind first when the phrase "digital camera" is mentioned (historically they were the first digital cameras), but the phrase is by no means exclusive to this type nowadays given that dSLRs and digital rangefinders are also digital cameras. But while the latter can be easily designated with these names, indicating both their design and their technology, LPDs do not have any widely-accepted specific name, and are usually designated by what they are not rather than what they are, hence expressions like "digital non-SLRs" or "non-dSLR's" are used to designated them. But such expressions are both awkward and non-specific (a "digital non-SLR" is not necessarily an LPD, it might be a digital rangefinder for example). Other commonly used names for an LPD include: 'Digicam' (the same as digital camera), 'point and shoot' or 'P&S' (many LPDs have full manual controls, using them as P&Ss is just an option), another name is 'compact digital cameras' (neither all the compact digitals are necessarily LPDs, nor all LPDs are compacts). So there is no one specific and commonly used name for them. The name "Live-Preview Digital camera" (and its acronym LPD) is specific and simple but is just a suggested one here in the hope that it will fill the gap (or that a better alternative will replace it here).
[edit] Compacts & bridges, the low- & high-end LPDs
LPDs include two different but not so distinct categories: Bridge digital cameras and Compact digital cameras. Bridge cameras in general are higher-end and more advanced (feature-packed), expensive (higher build quality) and sizable than the compacts.
[edit] LPDs vs dSLRs comparison
When considering the advantages and disadvantages of LPDs compared to dSLRs, the comparison is usually made between the best LPDs (bridge cameras) and the smallest and cheapest dSLRs, so most of what can be said in this respect is treated in the bridge camera article. Check in particular, the following sections in that article:
- One single fixed but versatile lens.
- LCDs and EVFs as principle viewfinders in LPDs.
- LPDs (bridges) vs dSLRs viewfinder comparison.
- Bridge cameras endangered and face unknown future.
A comparison between compacts and dSLRs would be really a very contrasted one in terms of size, weight, price, capabilities and image quality.
Almost all modern LPDs (whether bridges or compacts) have a movie mode while no dSLR has so far offered this option. All dSLRs on the other hand have a faster performance than LPDs in many areas (e.g. start-up time, shutter lag, continuous mode, autofocus...etc). This means that dSLRs are more reliable in situations (like sport or action photography) where being late for a fraction of a second may result in missing the right moment of taking the picture. The idea that dSLRs perform better than LPDs in high ISO-sensitivities, is right and wrong in the same time. It is wrong because good performance in this area has nothing to do with dSLR versus LPD as two different designs, it has to do rather with the sensor size of the camera, dSLRs always have large sensors while a great majority of LPDs have a small sensor and that is why the idea is in a way right, but with caution that it does not apply to a few LPDs with large sensor (e.g. the Sony R1).
[edit] Exceptional non-LPDs (dSLRs) with live-preview
There exist currently at least five dSLRs with live-preview: (the Canon EOS 20Da, the Canon EOS 1D Mark III, the Olympus E-330, the Panasonic Lumix DMC-L1 and the Leica Digilux 3), but the live-preview in some or all of these cameras is not conventionally-generated (the image formed by the lens is either not directly or not continuously projected over the main sensor). Also the live preview in these dSLRs does not serve as their principle means of framing and previewing before taking a photograph (as dSLRs, they have an optical view reflected in the OVF for that purpose and the live-preview is just available as an additional feature). Technological advancements may allow dSLRs to have a live-preview that is less and less distinct from that of LPDs, but the existence of a reflex system in a camera is enough in itself to justify a classification among dSLRs.
