SLR lens magnification how to see?
Basically, if the subject's position does not change, the focal length of the lens will be proportional to the magnification of the object: magnification = image size / subject size optical zoom.
For example: Sony Cybershot DSC-F828 digital camera lens focal length equivalent to 35mm camera 28 ~ 200mm focal length, we say it is 7 × optical zoom, which means that the original lens focal length of 28mm, through the lens system telescopic change, the maximum Adjust the focus of the lens to 200mm. At the same shooting distance, you can zoom in on the scene 7 times.
hint
How to see the magnification of the optical zoom from the digital camera body
★ We can calculate the magnification of the optical zoom from the zoom range (focal length) of the lens. For example: Sony Cybershot DSC-F828 digital camera lens, clearly marked "7.1 - 51", which means the zoom range (focal length) from 7.1 mm to 51 mm. Then you can calculate the optical zoom multiplier of 51 ÷ 7.1 ≈ 7.
★ Many digital camera body or lens will directly identify the optical zoom multiple, such as Sony Cybershot DSC-F828 digital camera at the top of the fuselage, clearly marked "7x Optical Zoom" (see Figure 1).
Today's digital camera optical zoom multiples of 2 times -5 times, you can 10 meters away from the object closer to 5-3 meters near; there are some digital cameras have 10 times the optical zoom effect. Home camcorder optical zoom factor of 10 times to 22 times, can be more clearly photographed 70 meters away things. Use the magnification mirror to increase the optical zoom factor of the camcorder. If the optical zoom factor is not enough, we can add a magnification lens in front of the lens, the calculation method is like this, a 2 times the teleconverter, set in a 4x optical zoom digital camera, then this digital The optical zoom factor of the camera is doubled, doubled, 6 times and 8 times from the original 1x, 2x, 3x, 4x, multiplied by the magnification of the teleconverter and the optical zoom multiplier.
Such as 50mm fixed focus lens is 50/50 is 1 times ah.
That is called the magnification and zoom ratio is completely completely two concepts ...........- - ||
The magnification rate is like a diameter of 1 cm coin on the film is the size of 1 cm, then the lens magnification is 1: 1, if the imaging size is only half (0.5 cm), then the magnification is 1: 2 ( That is, 0.5 friends)
Generally reach 1: 1 lens can be called macro lens, but now manufacturers are more wicked, can reach 1: 4 (that is, 0.25) of the lens will mark the macro words ... ...
his magnification and lens design, focal length, the closest focusing distance and so on parameters together determine.
Optical zoom to rely on the optical lens structure to achieve zoom, zoom mode and 35mm camera is almost through the camera lens to zoom in and zoom out the need to shoot the scene, the greater the optical zoom, the more distant shooting. Optical zoom, like traditional camera design, depends on the focal length of the lens, so the resolution and picture quality will not change. In other words, optical zoom can support the image of the main imaging, add more pixels, so that the main not only become larger, but also relatively clear. Usually the optical zoom magnification is suitable for telephoto shooting. Today's digital cameras have an optical zoom factor of between 2 and 5 times, and some digital cameras have 10x optical zoom effects.
