Differences between optical zoom and digital zoom, optical anti-shake and electronic Anti-shake

After fierce competition in terms of high pixel and small size, digital cameras have become a new keyword for digital cameras this year. Digital cameras of all major brands are capable of anti-shake.Article. All vendors in the market are divided into two factions: optical anti-shake and electronic Anti-shake. Representatives of optical anti-shake manufacturers are Sony, Canon, Nikon, etc. Recently Kodak was added, while electronic Anti-shake Manufacturers include Fuji, Olympus, Casio and Samsung.

We have all experienced that when using a digital camera to take a photo, it is inevitable that a tiny shake will occur when taking a photo with a hand-held camera. These seemingly insignificant shaking will usually lead to an offset of the optical axis during a shutter period, in this way, the photo will be blurred. The photos will not become blurred after the optical or electronic image stabilization technology is used.

There are two reasons for blurred images: Camera jitter and object movement. In environments with insufficient light, slight camera jitter may cause blurred pictures. When the subject moves fast (such as motion), the subject may be blurred.

Optical anti-shake is corrected through the optical system jitter, not to let the body not shake, it relies on the structure of special lenses or CCD photosensitive elements to minimize the unstable impact caused by jitter during use. Using the lens set to achieve image stabilization relies mainly on the magnetic package of the floating lens, so as to effectively overcome the blurred image produced by the camera vibration, which can play a significant effect on the digital camera of the large zoom lens.

Generally, the gyroscope in the lens detects a tiny movement and transmits the signal to the microprocessor to calculate the amount of displacement to be compensated immediately. Then, the lens group is compensated, compensation is made based on the jitter direction and displacement of the lens to effectively overcome Image Blur caused by camera vibration.

The optical image stabilization function is quite effective. Generally, enabling the function can increase the shutter speed by 2-3, so that the handheld shooting will not be blurred.

Let's take a look at Sony's T30 optical anti-shake process:

When the gyroscope located in the lower left corner of the camera detects the camera jitter, The DSC-T30 by moving a lens to adjust the incident angle of light, so as to prevent jitter phenomenon, ensure that the picture is clear.

The electronic Anti-shake function analyzes the images on CCD and uses edge images for compensation. Just like optical zoom and digital zoom, it only processes the collected data in a later stage. Olympus's anti-vibrationProgram(Anti-vibration program) "and Casio adopt this technology.

Specifically, the electronic Anti-shake function reduces the impact of the jitter by adjusting the parameter to increase the shutter speed. In most cases, the photo anti-shake effect is achieved by increasing the camera's ISO sensitivity value. Although increasing the ISO photosensitive value anti-Shake can indeed play a certain anti-shake effect, its anti-shake effect and optical anti-shake ratio are limited. In addition, the biggest weakness of increasing the ISO photosensitive value is: image noise increases and quality decreases. The electronic Anti-shake function only processes the collected data at a later stage, and does not cure the camera jitter index.

======================================
When purchasing digital cameras, we often see two indicators marked with "optical zoom" and "digital zoom". What are the meanings of these two indicators? In fact, the difference between them is a very important issue for digital photography.

Optical zoom is actually a real zoom result. It relies on the structure of the optical lens to achieve zoom. This method is similar to that of the 35mm camera. It is used to zoom in and out the scenes to be taken by moving the lenses of the lens. When the focal length is changed, the camera lens scales in the camera to achieve the best shooting effect. The larger the optical zoom factor, the farther the scenes can be taken. Currently, most digital cameras have an optical zoom factor of 2 ~ There are also some digital cameras with 7 to 6 times ~ 10 times the optical zoom lens. The optical zoom ratio of a home camera is 10 to 10 ~ Between 25 times, we can clearly capture things 70 meters away. If the zoom factor is not enough, you can add a multiplier in front of the lens to achieve the desired result.

However, digital zoom does not have any movable or scalable part. It uses the "electronic brain" inside the camera. It only scales up what it can observe, which is actually an electronic enlargement of the screen. That is to say, some pixels on the CCD sensor are amplified by interpolation. Through digital zoom, although the captured scenes are enlarged, their definition will decrease to a certain extent, and the larger the zoom factor, the lower the definition, so digital zoom does not have much practical significance. Currently, the digital zoom of a digital camera is usually about 3 times, and the digital zoom of the camera is about 44-600 times. In actual use, 40 times is enough.

When digital zoom is used, the degree of pixels is more serious than that when optical zoom is used, because the camera uses the "interpolation" processing method, it can only estimate the shape of a photo. At the same time, it is fine to use both optical and digital zoom methods, but I try to avoid using digital zoom alone.