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【Concept】
 
     Monocular camera, English as Single-lens reflex camera (the abbreviation SLR), Chinese name is generally translated as monocular reflex camera or a single-lens reflex camera
     Because monocular reflex camera or single-lens reflex camera to read it too long, the country is often called SLR cameras, SLR cameras, monocular or SLR;
     SLR appear to make up before TLR (twin lens reflex camera) and rangefinder camera numerous defects appear, using the same camera for framing and shooting (it is also called TTL viewfinder, ThroughThe Lens), its basic design to avoid the viewfinder parallax problems.

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【Principle term】
 
1. In a monocular camera systems, mirrors and prisms unique design allows the photographer can be observed directly from the viewfinder image through the lens. Therefore, we can accurately see the film or digital sensor will "see" the same image.
2. The heart of the system is a mirror activities, it was placed in a 45 ° angle in front of the film plane. Light entering the lens is reflected by the mirror up to a ground glass.
3. Early SLR camera must be a way to grasp the waist level and overlooking the ground glass viewfinder camera.
4. Although the image on the ground glass is upright, but the left and right are reversed. To correct this defect, now eye-level type SLR camera mounted on top of a frosted glass pentaprism. This prism multiple reflection of light to change the optical path to the eyepiece of its image, the image is then ground down upright and about a correction.
5. When the viewfinder, most of the light entering the camera's mirror reflection are up to five prism, almost all SLR camera shutter are located directly in front of the film (due to this film plane shutter is located, and thus called focal plane shutter)
     When shooting, the shutter is closed, no light reaches the film.
6. When you press the shutter button, the mirror flips up so quickly open the optical path, while the shutter is open, so the light reaches the film shoot.
7. Then, most cameras in the mirror will immediately reset....

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【Term key components】
 
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 1, [Mirror]
 
     Its role is through the photographic lens reflex viewfinder with image on the focusing screen;
     Mirror is a plated silver reflective material on the surface of the glass (note that it is not like a mirror reflective material that is coated on the back of the glass, but the top, so the normal maintenance of the camera as little as possible to wipe the mirror, even if dust on the mirror, it would not affect imaging), 45 ° hinge in the mirror box.
     Before unexposed, mirror effect is to change the optical path, reflected to the viewfinder, the operator can correctly framing and focusing.
     Before the shutter is open, the mirror turned upward, so that the optical path after the shutter was open, exposing the light reaches the film plane.
     After the exposure process, the mirror immediately return to its original position, that instant-return mirror.

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 2, [Focusing Screen]
 
     Is used to examine the role of focus.
     The focusing screen is equivalent to an ideal plane of the film, i.e., from the mirror to the distance between the focusing screen mirror film plane to the distance is equal.
     Usually matte frosted glass Fresnel lens, before unexposed, instead focusing screen film plane that focus.
     When the focus is accurate, clear image focusing screen will appear.
     Since the optical reflection principle, the picture on the focusing screen and the actual picture is laterally reversed, through five edge finder to be rectified;

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 3. [pentaprism viewfinder]
 
     Its role is reversed left to right on the focusing screen image rectified see the viewfinder image is completely consistent with the position directly to see the scene.
     Pentaprism is usually a solid piece of glass after cutting and grinding, and then the outer (except the two faces of the focusing screen and viewfinder eyepiece contact) were plated reflective material to form a specular reflection in its interior.
     The viewfinder has two main indicators: Viewfinder magnification (referred to as the viewfinder magnification) and shooting range.

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 (1) Viewfinder magnification
 
     Refers to the observation of the subject and the opening angle of the eye directly observed with the eyes of the subject on the eye opening angle ratio, i.e. seen through the viewfinder subject size directly visible with the eye, the subject through the viewfinder the ratio between the size.
     Viewfinder magnification of large and small visual angle, when the viewfinder to see the scene close to the original, realistic strong;
     Viewfinder magnification zoom small visual angle, is easy to see when shooting panoramic. If the magnification is too small, it is difficult to observe the object detail is not conducive to composition and focus, but also things like the differences between uncomfortable viewing. Magnification is generally less than 1X, mostly between 0.75X and 0.95X.

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 (2) the shooting range
 
     Refers to the ratio of the scope of the scene by scene and shooting range finder to see in the end pieces, expressed as a percentage.
     Generally seen from the viewfinder screen is not entirely the footage, the footage is always better than smaller, typically 90% to 100%. So just basically avoid parallax SLR, only to reach 100% of the shooting range can be called no viewfinder parallax.
     Only professional models usually only have 100% shooting range.

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【Advantages  Terminology】
 
 1. SLR (eye) camera - only a single lens reflex camera lens, using it both photography also use it for filming, so the parallax basic problem is resolved.
 2. When the framing of the light from the subject focused by the lens, is reflected to the oblique mirror imaging the focusing screen, and then through the top of the ridge from the "roof prism" (Note) reflection, the photographer can be observed through the viewfinder eyepiece scenery, and is down about all the scene the same image, so framing, focusing very convenient.
 3. photography, the mirror will immediately bounce back, lens aperture automatically shrink to a predetermined value, so that the shutter is open Film; after the end of exposure shutter closes, the mirror and the lens iris is reset at the same time.
 4. Single-lens reflex camera can freely switch to its support of a variety of wide-angle focal length, telephoto or zoom lens, close-up lens can also be installed in the lens as needed, plus access extension or expansion bellows connected to the ring.
 5. Where a word from the viewfinder to see the scene, the camera can shoot down.
 6. Simple to use 120 film single-lens reflex cameras generally do pentaprism (such as the Great Wall DF-4 type), can be directly on the ground glass viewfinder, focus; in high-end single-lens reflex camera can also put a plan view of the viewfinder (eg Pearl S-201, Nikon F3), so the same can be like a twin-lens reflex cameras viewfinder low tilt or inverted.
     This is the single-lens reflex camera twin-lens reflex camera gradually replace one of the reasons.
 
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【Term Disadvantages】
 
 1. Increase the mirror and pentaprism room after the body heightening, thickened, add weight;
 2. mirror bounce the moment there will be a mechanical vibration and noise;
 3. Press the shutter button to start the shutter interval is also slightly longer than the other cameras;
 4. Use a small aperture lens in poor light environments framing, focus, due to difficulties arising from the viewfinder screen is dark, the focus could easily lead to mistakes.

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【Digital monocular monocular and traditional terminology】
 
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 1, [high-pixel CCD]
 
     General SLR cameras have 8 million or even higher pixel CCD or CMOS
     The digital SLR also has more than 800 million effective pixels CCD. Currently specializing in full-frame digital SLR's pixels are higher, more suitable for professional use.

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 2, [having more excellent image quality, level of detail is more delicate]
 
     As the sensor area due to the larger SLR, digital SLR cameras easier to get good imaging.
     Lens and relatively richer, richness and image quality lens group is an important factor in selecting film friends.
 
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 3, [manual ability]
 
     Manual adjustment function has become a must-have feature digital SLR, but also their professional representatives.
     And many of the manual exposure and white balance functions are two important aspects. In some cases the photographer wants to get overexposed or underexposed image effects, and even in some cases based on the experience of the photographer, not the normal exposure metering system in accordance with the value, so you need to manually control the exposure and color temperature, in order to achieve good shooting.
     This is also reflected in professional digital SLR.

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 4, [response rate]
 
     Because of its focus system is independent of the imaging device outside, they are basically the same can be achieved with a traditional SLR response speed, in news, sports, photography allows users handy.

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 5, [volume and price]
 
     For SLR cameras because the internal integration of large-size CCD or CMOS therefore relatively bulky appearance, the attendant costs also increased, along with the price and relatively expensive.
 
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【Article is excerpted from: Web Search】
【Reserved Integrate / Just Reference】
【Translation is by The Network】