Observation mode of optical viewfinder

As the name implies, the optical viewfinder is the composition of the viewing range observed by the human eye through a set of optical mechanisms on the camera. In the optical viewfinder, there are two kinds of framing methods: paraxial head-up and single-lens reflective coaxial framing. Among consumer digital cameras, the paraxial head-up camera is the most common and common. What kind of viewfinder is paraxial head-up view? In fact, it's not complicated at all, it's just the viewfinder window of the "stupid machine" we often say. Let's take the famous Canon POWERSHOTG2 camera as an example, which uses a fairly typical paraxial viewfinder system. When shooting with G2, the light of the shooting scene directly enters from the viewfinder on the front of the camera, and then enters the eyes of the observed person from the viewfinder on the back of the camera. The route is simple and clear. To put it bluntly, it is almost as simple as opening a small hole in the camera body, installing glass, and letting eyes see the scenery in front through the camera body. In fact, the structure of G2 viewfinder is not so simple, and there are auxiliary lines, zoom lens and other components in it, but overall, the structure is relatively simple and the principle is not complicated. Because of this, the paraxial head-up viewfinder is relatively small in size and low in manufacturing cost, so it is widely used by various digital camera manufacturers.

However, for a camera with paraxial head-up, the position of the observation window and the lens cannot be the same but separated, so there is a certain difference in size and position between the image seen from the viewfinder and the actual electronic image, which is called "parallax" in photography. This kind of parallax is not a big problem when taking a long shot, but strange problems such as different framing range and final imaging angle, composition error and so on often appear when taking a close shot. From a photographic point of view, this is not conducive to really doing a good job of framing and composition.

In order to solve this problem, some digital camera manufacturers apply the single-lens reflective coaxial framing technology widely used in traditional 135 cameras to consumer-grade DC. Single-lens reflective coaxial viewfinder, referred to as "SLR camera". From the front appearance of the camera, you can't find any other viewing window except the lens itself. So, how does the light of an object work if it is transmitted to the operator behind the camera? Let's take Olympus's E-20 digital camera as an example: the light from the shooting scene reaches a mirror inside the camera through the lens, then refracts to the focusing screen above to form an image, then passes through the optical eyepiece and prism, and then enters people's eyes through the observation window on the back of the camera. This framing structure of the SLR camera ensures that what people see when framing is the scene that will be shot diagonally through the lens. To paraphrase the computer industry, what you see is what you get. Moreover, whether the camera is focused accurately or not and the change of focal length can be clearly seen through the viewfinder. Because the viewing range of the single-lens reflective coaxial viewfinder is basically the same as the actual shooting range, there is no parallax phenomenon with the paraxial head-up viewfinder. Such a viewfinder is of course very beneficial to photography, which allows us to view and compose pictures intuitively. At the same time, the camera with SLR viewfinder can also see the camera shooting parameters in the viewfinder.

LCD frame

This is a necessary way for most digital cameras to view. The only advantage of LCD framing is that it corrects the only disadvantage of ordinary optical framing. However, just like Windows 98, the bug of Windows95 was fixed and more bugs were generated. Let's take a look at the shortcomings of LCD framing: first of all, LCD is a big power consumer, accounting for more than 1/3 of the whole camera; Secondly, the position of LCD framing must be that both hands stretch forward and keep a certain distance from the eyes. At this time, the camera can not get stable triangular support, so it is difficult to take stable and clear photos with low-speed shutter. Finally, the color and contrast of the picture displayed on the LCD are very different from those actually seen in the computer. Even the LCD with a nominal million pixels looks rough and cannot observe the details of the main body. Faced with this kind of picture, it is difficult for you to judge whether the photos you have taken meet your requirements. Fortunately, the digital camera is equipped with both ordinary optical framing and LCD framing. If you buy a digital camera with only an LCD viewfinder, unless you are sure enough to get the desired results, there are certain risks.