Structure
In the film camera shutter assembly, the way of driving the shutter "curtain or hinge" action is divided into two categories: pure mechanical drive and mechanical-electromagnetic drive. Among them, mechanical transmission and spring delay are "pure mechanical shutters"; mechanical transmission and electromagnetic triggers are electromagnetic shutters; later developed to high-speed gears with spring delays and slow-speed gears with electronic circuits. This is called "electromagnetic triggering". , Electronic time-delay shutter". They all belong to the category of "shutter with door", but the difference between the "means" of "opening" and "maintaining time".
Difference
One
Vertical-travel shutter
The "mechanical shutter" and "electronic shutter" discussed in the digital camera industry today The difference between "" refers specifically to "what means is used to achieve instant exposure", the two are actually not a concept at all, even though they are both called "shutter."
Mechanical shutters are easier to understand: use mechanical springs or electronic or electromagnetic means to control the opening and closing of several blades, or two curtains with a certain width left and right or up and down like a stage "pull screen" The gap "slides through" the imaging image field window, allowing the window to obtain a "light opportunity" for a specified length of time-this is the usual "mechanical shutter" concept, that is to say, like a traditional camera, the image exposure is through a physical The "time-limited opening and closing" of the "door" of existence is completed.
Two
The electronic shutter is different. It does not actually have a "gate", but uses the principle that the CCD photosensitive system does not work when the CCD is not energized. Next, although the image field window is still "largely open", it does not produce an image. If you use an electronic time circuit when you press the shutter button to make the CCD only work for "a specified length of time", you can get the same effect as if the shutter "opens instantly". Therefore, the electronic shutter digital camera is "silent" when the shutter is pressed. However, in order to meet the "psychological needs" of movie friends, some cameras can set an "electronic sound": simulate a "click" sound to make you "excited".
Obviously, the electronic shutter has a simple structure and a much lower cost. Therefore, pocket card digital cameras and other medium and low-end digital cameras basically use electronic shutters, while high-end home digital cameras and all digital SLR cameras use mechanical shutters without exception.
Three
The mechanical shutter of a digital SLR camera is actually the same as its prototype, the film camera shutter assembly, and there is no big difference. Therefore, there are no special new requirements for service life and maintenance.
Four
In addition, some manufacturers use the characteristics of electronic shutters to allow the CCD to be controlled by the electronic shutter while the mechanical shutter is opened. This can be achieved at low cost. To achieve special requirements. For example, the same 1/4000 second mechanical shutter, if you precisely control the power pulse of the CCD, you can make it realize the ultra-high-speed shutter function of 1/8000 second and 1/16000 second. Such a shutter is called a "mechanical and electronic hybrid" shutter.
Five
This also explains why most home digital cameras (including mobile phones) can have the function of continuous recording, while digital SLRs do not have this function. Because the home machine is not blocked by the "door curtain", it can take pictures continuously when it is powered on; while for the digital SLR to take pictures continuously, it must have a "T door" gear that can always keep the shutter blades open. OK, and this requires a long time electromagnetic attraction and consumes a lot of power.
Generally, the inter-lens shutter and the focal plane shutter are collectively referred to as a mechanical shutter: the inter-lens shutter is operated mechanically, and the shutter speed cannot be too high, usually from 1 second to 1/1000 second Not waiting. Most of the 120 cameras are inter-lens shutters, and some of the 35 mm compact cameras are inter-lens shutters. The advantages of the inter-lens shutter are: precise structure and high efficiency; any fast-moving objects will not be deformed; when shooting with a flash, it is not limited by the shutter speed, and the photosensitive film can be fully exposed at any speed. The inter-lens shutter also has a certain degree of defects: the efficiency of the light flux of the shutter varies with the size and speed of the aperture. When the aperture is large and the shutter speed is high, the light flux efficiency is low. The focal plane shutter, usually called the curtain shutter, has the advantages: tight structure and high speed; the curtain is close to the crack of the photosensitive film from one end of the film to the other. It produces the phenomenon of underexposure at high speeds and large apertures like the shutter between the lenses. With the development of electronic science, advanced electronic technology is also applied to the shutter of the camera, using electrons to control the exposure of the shutter, which is called electronic shutter. Electronic shutters are divided into fully electronic and electronic and mechanical types. The fully electronic shutter uses the battery in the body as the energy source to automatically control the metering and exposure; the electronic and mechanical shutters are limited to one or two speeds and can be controlled by the mechanism, while the other multi-speeds are all electronically controlled.