What is a DSLR camera

What is a "DSLR" camera and what does it mean?

"SLR" means single-lens reflex. That is, SLR (Single?Lens?Reflex), which is also the viewfinder used in most 35mm cameras in the film era. In this type of viewfinder system, the unique design of the reflector and prism allows the photographer to observe the image imaged through the lens directly from the viewfinder. As a result, it is possible to see exactly the same image that the film or CCD is about to "see". The heart of the system is a movable reflector, which is placed in front of the imaging plane at a 45° angle. The light entering the lens is reflected upward by the reflector to a piece of hair glass. The image on the glass, although upright, is reversed from side to side. To correct for this defect, today's eye-level SLR cameras have a pentaprism mounted above the hair glass. This prism reflects the light several times to change the optical path and sends the image to the eyepiece, where the image is upright up and down and corrected left and right. When framing, most of the light entering the camera is reflected upward by the reflector to the pentaprism, almost all SLR camera shutter is located directly in front of the film (because the shutter is located in the plane of the film, and therefore called focal plane shutter), when framing, the shutter is closed, no light reaches the film. When the shutter release button is pressed, the reflector quickly flips up to clear the light path and the shutter opens, so light reaches the film and the shot is taken. The mirror in most cameras is then immediately reset. The principle of framing in a digital SLR camera is the same as in a film SLR camera.

The flip-up action of a DSLR's mirror also poses some other problems:?

One, the viewfinder will be blocked at the moment the photo is taken. Since the time of being blocked is a matter of split second, this is not a major problem for a mirror that resets immediately. But again, it leads to some incidental problems. For example, when shooting with a strobe, it will not be possible to see through the viewfinder if the strobe unit is flashing properly.?

Two, noise from the movement of the reflector. This can be a significant problem in places where quiet is required. Since there is no moving reflector in a rangefinder camera that suddenly blocks the light path, there is no such noise.

Third, camera shake, which is the overall movement of the camera caused by the flip-up action of the mirror. Assuming that you are shooting at a shutter speed of 1/500th of a second, there is nothing to worry about. This vibration is not enough to be noticed. However, if an accurate picture is taken at a lower shutter speed, such as when shooting with a telephoto lens in low light, the result will be affected.

On top of that, there's another problem with SLR framing. For example, if we want to shoot with a small aperture like f/32, and the light allowed into the lens by the aperture f/32 is very faint, this will result in a dim image seen in the viewfinder as well, which may be difficult to focus on, or even impossible to focus on at all.?

In fact, SLR's solution is quite ingenious,? It will first use the lens's largest aperture to allow us to finish framing and focusing, and when the shutter is pressed, the lens's aperture will immediately contract to its preset aperture to complete the film exposure, and the moment the exposure is complete, the aperture will open back up to its largest aperture in preparation for the next shot.?

Advantages of a digital SLR: ?

The professional positioning of digital SLR cameras determines that even popular products for ordinary users and enthusiasts have a lot of advantages, which is the fundamental reason why many enthusiasts choose digital SLR cameras. We can summarize the advantages of DSLRs into the following aspects:?

1, the advantage of the image sensor?

For digital cameras, the sensor is one of the most important core components, its size is directly related to the effect of shooting, in order to achieve good shooting results, the most effective way is not only to increase the number of pixels, it is more important to increase the size of the CCD or CMOS. Whether using CCD or CMOS, the sensor size of DSLR is much larger than that of ordinary digital cameras. As a result, the pixel count of DSLR sensors is not only higher (currently at a minimum of 6 million), but the area of a single pixel is four or five times larger than that of a civilian digital camera, resulting in a very good signal-to-noise ratio and the ability to record a wide range of brightness. 6-megapixel DSLRs have an image quality that definitely exceeds that of an 8-megapixel digital camera with a 2/3-inch CCD.

2. Abundant lens options?

Digital cameras, as a kind of optical, mechanical and electrical integration of products, the performance of the optical imaging system on the final imaging effect of the impact is also quite important to have an excellent lens for imaging the significance of the image sensor is by no means less than the choice. At the same time, as the cost of image sensors, image engines and memory devices continue to reduce, optical lenses in the cost of digital cameras accounted for a larger and larger proportion. For digital SLR is more so, in the choice of traditional SLR cameras, the richness of the lens group and imaging quality is an important factor in the choice of the photographer, to the digital era, the lens group of the retention rate of the brand competition has become the basis of the logical. Canon, Nikon and other brands have a large group of autofocus lenses, from ultra-wide-angle to ultra-telephoto, from macro to soft focus, users can choose the matching lens according to their needs. At the same time, due to the large sensor area, digital SLR cameras are easier to get excellent imaging. What's more, in the hands of many photography enthusiasts, generally have one or two, or even up to a dozen of a variety of professional lenses, these are the photographer with their own hard-earned money to buy, if you buy a digital SLR camera body, all of a sudden, the lens revitalization, but also and the original traditional film camera constitutes a mutually complementary film and digital two systems.

3, rapid response speed?

One of the biggest problems with ordinary digital cameras is that the shutter lag is long, and you often miss the most exciting moments when you are not good at capturing them. Response speed is exactly the advantage of digital SLR, because of its focusing system independent of the imaging device, they can basically realize and traditional SLR the same response speed, in the news, sports photography, let the user handy. Currently Canon's EOS1D?MARK II and Nikon D2H are both capable of continuous shooting speeds of up to 8 frames per second, which is comparable to traditional film cameras.?

4. Excellent hand control?

While today's cameras are more and more capable of shooting automatically, the environment and the situation of the subject are ever-changing, so a user with certain requirements for photography will not be satisfied with shooting in automatic mode. This requires that digital cameras also have the ability to be manually adjusted, so that users can make adjustments according to different situations in order to achieve the best shooting results. Therefore, the manual adjustment function has become a must-have function for DSLRs, which is also the representative of its professionalism. Among the many manual functions, exposure and white balance are two important aspects. When the automatic metering system cannot accurately judge the light condition and color temperature of the shooting environment, it is necessary for users to judge according to their own experience and manually make forced adjustments in order to achieve good shooting results. This is also a reflection of the professionalism of digital SLRs, such as the EOS10D's ability to adjust the color temperature value at 100K per shot to help users get the best results.?

5, rich accessories?

Digital SLR and ordinary digital cameras an important difference is that it has a strong scalability, in addition to the ability to continue to use additional lenses such as polarizer and interchangeable lenses, you can also use professional flash, as well as some other auxiliary equipment to enhance its ability to adapt to a variety of environments. For example, high-power flash, ring macro flash, battery grip, timing remote control, these rich accessories allow digital SLR can adapt to a variety of unique needs, while the ordinary digital camera is greatly inferior.