How to distinguish the lens of SLR camera?

There are many kinds of lenses in SLR cameras, which are easy for beginners to understand. Let me classify it from several aspects. After watching it, you can have a general understanding of the lens.

Original factory x vice factory

The original lens is the matching lens produced by camera manufacturers themselves, such as Canon and Nikon. Deputy factory refers to supporting lenses that are not authorized by camera manufacturers, such as Sigma and Longteng. Deputy factory lens does not mean fake, but it is not authorized by the original factory. For example, if you buy a non-Xiaomi brand charging treasure to charge Xiaomi mobile phone, it doesn't mean that this charging treasure is fake. The lens of the vice factory is also divided into bayonet, which is the interface with the fuselage. Don't buy it wrong. Although the lens quality of the sub-factory is not the same as that of the original factory, it can still reach a certain quality. The advantage is high cost performance. For example, the Sigma 70-200mm F2.8 lens costs only 6000 yuan, and the original factory costs at least 1 10,000 yuan.

Floating aperture x constant aperture

This is one of the most important factors to judge a shot. Floating aperture means that there are two maximum apertures, such as 3.5-5.6, which will change with the change of focal length. As shown in the figure, when the focal length is 18mm, the maximum aperture of F3.5 can be opened; When the focal length becomes 250mm, the maximum aperture can only be opened to F5.6. As long as it is a floating aperture, it must be a zoom lens, and vice versa.

Constant aperture means that the maximum aperture is fixed and will not change because of the change of focal length. For example, a fixed-focus lens has a constant aperture. For the same focal length, the constant is more expensive than floating, and the larger the aperture, the more expensive the lens.

Zoom x fixed focus

Focal length refers to the viewing angle range of lens shooting. Zoom means that the lens has multiple focal lengths, such as the classic zoom lens 24-70 mm If the focal length is short, the number is small, such as 18mm, and the shooting angle is wide, it is called wide angle. A long focal length means a large number, such as 200mm, and a narrow shooting angle, which is suitable for shooting distant objects, called telephoto. Fixed focus means that only one focal length cannot be changed, such as 50mm fixed focus. At the same price, the quality of fixed-focus lens is better than that of zoom lens. The larger the zoom span, the worse the quality, and the one that can guarantee the quality will be very expensive.

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