Introduction
135 film uses a 35mm motion picture film, its width is 35, then in front of that 1 is how it happened? Oscar Barnack Leica camera designed for first use 35mm movie film, but a start must be put into the film cassette reusable years, the titles cut, before the shooting. In 1934, Kodak introduced the disposable cartridge 135, which is actually in Stuttgart, Germany plant of the invention Nagel camera, Kodak acquired the plant. Kodak officially launched in 1935 and 135 Kodak color film. So, 135 means that 1 is different from the reusable cartridge disposable cassette 135 film full definition was "a one-time use of 35mm film cassette."
135 different backing film is generally classified into a roll 36, because the machine has 120 6 × 6,6 × 7,6 × 9,6 × 10 other frame, so the 120 sheets of film can take 9-12 Photo. 4 × 5,8 × 10 large format camera using a single page piece, one shot one or two films.
Conclusion: Effect seen from the viewfinder by: a reflector (mirror), the secondary reflection (Pentaprism)
CCD acquired image information is captured when bounce mirror moment, the shutter is opened and exposed.
often hear people say, "SLR camera" SLR What exactly is it? SLR refers to the single-lens reflex, that is, SLR (Single Lens Reflex), which is the most popular framing system, most 35mm cameras are using this viewfinder. In such a system, mirrors and prisms unique design allows the photographer to the viewfinder can be observed directly through the lens to the image. Therefore, we can see exactly the same image film soon to be "seen". The heart of the system is an active mirror, which was placed in a 45 ° angle in front of the film plane. Light entering the lens is reflected by the mirror up to a frosted glass. Early SLR camera must grasp the camera at waist level and top ground glass viewfinder. Although the image on the ground glass is upright, but the left and right are reversed. To correct this defect, the present eye-level type SLR cameras installed above a frosted glass pentaprism. Such multiple reflection prism to change the optical path of light, the image it to the eyepiece, then the image is upright and the vertical correction of the left and right. When framing, most of the light entering the camera is reflected in the mirror up to the pentaprism, shutter almost all SLR cameras are directly in front of the film (due to the film plane is located in such a shutter, so called focal plane shutter), framing , the shutter is closed no light reaches the film. When the shutter button is pressed, the mirror upturned quickly get out of the light path while the shutter is open, then the light reaches the film, shooting is finished. Then, most of the camera in the mirror would immediately reset.
mirror flips this necessary action also brought a number of other issues:
First, take a picture of the moment, the viewfinder will be blocked. Because time is blocked just an instant thing, so this is what the main problem is not immediately reset to mirror it. However, it raises a number of contingency issues. For example, when using stroboscopic photography, can not be seen through the viewfinder strobe flash device is normal.
Second, the mirror movement noise. This needs a quiet place which could become an important issue. Since the range finder camera is not moved abruptly blocks the light path of the mirror, this noise is not generated.
Third, the camera shake, i.e., the mirror flips operation caused by movement of the whole camera. Suppose to shoot with a shutter speed of 1/500 second, so do not worry. The vibrations are not to be noticed. However, if an accurate picture shot at a lower speed, then the shutter, such as a telephoto lens used in shooting under faint light, the vibration of the imaging may be problematic.
In addition, using the SLR viewfinder there is another problem. For example, we want to use the f / 32 aperture to shoot such a small, and the aperture f / 32 to allow light to enter the lens is very weak, which causes the viewfinder to see the images are very dark, you may difficult to focus, or simply unable to focus.
In fact, SLR solution is quite clever, it will first use the maximum aperture of the lens allows us to complete the framing and focus, press the shutter, lens aperture will shrink immediately to the preset aperture, complete film exposure, the exposure is completed in the moment, it will open the aperture to its maximum aperture, ready for the next shot.
First, choose a digital SLR for several reasons:
professional digital SLR camera positioning, decided that even for ordinary users and enthusiasts of popular products also have a large number of extraordinary at which many enthusiasts choose a digital SLR camera underlying causes. We can put professional characteristics of digital SLR comes down to the following aspects:
1, the advantages of the image sensor
For digital cameras, the sensor is the most important part of the core First, its size is directly related to the effect of shooting, in order to achieve good results with, it is not only the most effective way to increase the number of pixels, the more important is to increase the size of the CCD or CMOS. Whether using CCD or CMOS, digital SLR camera sensor size are far more than an ordinary digital camera. Therefore, the number of pixels sensor digital SLR is not only relatively high (the current minimum 6 million), and a single pixel area of consumer digital cameras is four or five times, and therefore has a very good signal to noise ratio, you can record a wide range of brightness. The image quality of digital SLR cameras is definitely more than 6 million pixels image quality using 800-megapixel digital camera 2/3 inch CCD's.
2, lens selection rich
a digital camera as an optical, mechanical, electrical integration of the product, affect the performance of the optical imaging system to the final image is also very important effect , with a superb shot no less significance for the imaging of the image sensor of choice. Meanwhile, as the cost of the image sensor, an image engine and a memory device continues to decrease, the proportion occupied by the optical lens digital camera cost is also increasing. An important factor for digital SLR is concerned especially in the traditional SLR camera choices, richness and image quality Photographic lens group is selected, to the digital age, the lens group retention rates naturally become the brand a competitive basis . Canon, Nikon and other brands have a huge autofocus lens group, from ultra-wide angle to super telephoto, from macro to soft focus, the user can select the matching lens according to their needs. Meanwhile, due to the large area sensor, digital SLR cameras easier to obtain an excellent image. More importantly, many photography enthusiasts hand, generally have one or two, or even as many as a dozen of a variety of professional lenses, these are the film Friends with their hard-earned money to buy, if you buy a digital SLR camera body , that'll activate the camera, and the original and traditional film cameras constitute a complementary film and digital two systems.
3, quick response time
ordinary digital camera biggest problem is the long shutter lag, often handled badly miss the most exciting moment in the capture. Response time is the advantage of a digital SLR, because of its focusing system independent of the imaging device outside, they can be achieved basically the same as the traditional SLR and response speed, allowing users handy in news, sports photography. Currently Nikon D4s can reach the burst rate of 11 frames per second, comparable to traditional film cameras.
4, excellent manual ability
Although today's cameras automatically capture function is getting stronger, but because the shooting environment, the situation is changing the subject, So there are certain requirements for a photographic user is not satisfied merely to use the automatic mode shooting. This requires a digital camera also has the ability to manually adjust, so that the user can be adjusted according to different situations in order to achieve best results. So with manual adjustment function digital SLR has become a must-have features, but also its professional representatives. The exposure and white balance are two important aspects of the many manual functions. When shooting automatic metering system can not accurately determine the color temperature of light conditions and the shooting conditions, the user needs to be determined according to their own experiences, to be adjusted by manual force, in order to obtain a good shooting. This is also reflected in the digital SLR professional, such as EOS10D able to adjust the color temperature of 100K each value as a reference to help users get the best results.
. 5, attachment rich
an important distinctionand general digital SLR digital camera is that it has highly scalable, in addition to other additional polarizers continue to be used and the interchangeable lens off-camera, you can also use a professional flash, and other ancillary equipment to enhance its ability to adapt to various environments. For example, high-power flash, macro ring flash, battery grip, regular remote control, so that these rich digital SLR accessories can be adapted to a variety of unique needs, while ordinary digital camera is greatly inferior.
principles
SLR stands for single-lens reflex, SLR camera is framing a single-lens reflex camera for the image was obtained through observation photography. SLR camera viewfinder called TTL (Through The Lens) SLR viewfinder. This is an essential professional camera viewfinder model, which is really no error, through the lens of the optical viewfinder. This shooting range finder Sign up to 95% of the screen. The only drawback is that if the lens is too small, the viewfinder will be very bleak, affecting manual focus. Fortunately, now with auto focus, it uneventfully. Of course, as with the TTL SLR viewfinder, the viewfinder in order not to make too dark, since manufacturers will use large-caliber high-level lens, so the current SLR camera lens generally larger, is due to this factor.