SLR Cameras Explained

June 21, 2009

An SLR camera is a Single Lens-Reflex system camera in which there is a moving mirror present that tells the photographer the exact overall picture settings, mode and quality, beforehand that will be captured by the camera. An SLR system maybe incorporated in a film or in a digital camera both. Before the advent of SLR cameras, the cameras used to have a viewfinder consisting of two optical light paths; going towards the film via lens and the other to the above or to the side. This posed parallax error when a close up shot was taken though the pictures taken from a distance seemed to be fine. Plus, these non-reflex cameras were not easy to work with in low lights or when the lens was used at a wider aperture.

The imaging is made more perfect by the incorporation of a pentaprism system which aligns the light reflected by the movable mirror with the viewfinder and when the shutter is released, the mirror gets out of the light path so that it falls directly on the film or on the CCD or CMOS sensor (in case of DSLR camera).

The SLR cameras also provide accurate focusing both manually and by the Auto focus automatically. Though, these cameras do not have the facility of an LCD preview, they still have an edge over the DSLRs in terms of picture clarity and finer details made possible by the viewfinder.

Mostly SLRs have the roof penta prism system; however, other types are also available such as the waist-level finder which is an exchangeable sports finder as used in the Canon F1 and F1n, etc. A photographer can make use of the Right angle view finder as well that can fit on to the eye piece in every other SLR or DSLR camera and can view the image even without a waist- level finder. Some cameras also support an EVF remote finder that can enable the user to have a wider view.

The SLR cameras traditionally contain a focal plane shutter that is situated before the film plane. It obstructs the light path going towards the film even when the lens is not in its place but allows the light to fall on the film when the shutter is released to take the photograph. The focal plane shutters are available in different designs. The usual focal plane shutter consists of two curtains, an opening shutter curtain and a closing shutter curtain. When the shutter speed is high, the opening shutter curtain forms a horizontal slit aand the other one forms a vertical opening closely behind the first curtain.

One of the most frequently faced problems or more precisely aberrations is the image distortion. This may occur due to the nature and shape of the lens. To solve this problem some cameras provide the Perspective correction lenses usually in the 35mm and medium formats. These distortions in digital camera however, can be corrected with photo soft wares. Not only this, the SLR cameras also gives a photographer, the freedom to expand the bellow up to its maximum length while tilting the front standard and can capture microscopic subjects with par clarity and image sharpness without having to adjust the lens diaphragm.

So if comparing SLRs to DSLRs, one would have to admit that despite the plus points the latter has to offer like the LCD preview option, the former type of cameras are still the best in terms of picture quality, sharpness and also show lesser incidence of aberrations which makes them more popular among the professional photographers.

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