Lens classification of SLR cameras? Be more specific! Thank you!

Fixed focus lens: A lens with a fixed focal length is called a "fixed focus lens".

1. standard lens (referred to as header): refers to the lens whose focal length is close to or equal to the diagonal length of the film/sensor. For a Quan Huafu 135 SLR camera, the negative width is 24*36mm, and the diagonal length is 50mm, so the focal length of the camera's "head" is 50 mm ... Of course, the focal length of different cameras is different. Generally speaking, the focal length of a 120 camera is 75mm, and that of a 4*5-inch landline is150 mm. The sensor format of a digital SLR camera varies from manufacturer to manufacturer, but as long as the diagonal length of the sensor is calculated, the focal length of a standard lens can be obtained. Although the focal lengths of the "heads" in different frames are different, their visual angles are basically the same, which is close to the normal visual angle of human eyes. Therefore, in terms of framing range and perspective relationship, the "title" is similar to the effect of human eyes, which is particularly cordial and natural. In addition, the technology of "head" is basically perfect, with the remarkable characteristics of large aperture, outstanding imaging quality and low price, and it is one of the necessary lenses for every SLR user.

2. Wide-angle lens:

Refers to the lens whose focal length is shorter than the "head" and whose viewing angle is larger than the "head". For Quan Huafu 135 SLR cameras, the lens with a focal length of about 30mm and a viewing angle of about 70 degrees is called a "wide-angle lens", and the lens with a focal length of less than 22 mm and a viewing angle of more than 90 degrees is called a "super-wide-angle lens".

Features of wide-angle lens: A. The depth of field is large, which is conducive to obtaining all clear images. Widely used in the shooting of scenery films. B. The viewing angle is large, and a wider range of framing can be obtained in a limited range, especially the shooting of indoor buildings, which is widely used in the real estate industry. C. strong perspective can create a picture with strong visual impact. D. Distortion is large, especially at the edge of the picture.

3. telephoto lens:

Refers to a lens whose focal length is longer than the "head" and whose viewing angle is smaller than the "head". For Quan Huafu 135 SLR cameras, a lens with a focal length of 200mm and a viewing angle of about 12 degrees is called a telephoto lens, and a lens with a focal length of over 300mm and a viewing angle of about 8 degrees is called a super telephoto lens.

Features of telephoto lens: A. The depth of field is small, and it is easy to obtain the picture effect with clear subject and blurred background. B. The viewing angle is small, so that a larger picture of the distant subject can be obtained without disturbing the subject. Widely used in outdoor wildlife shooting. C. It compresses the feeling of jumping in perspective and shortens the distance between foreground and background. D. the image distortion is small, and it is widely used in portrait photography.

4. Fisheye lens:

An extreme super wide-angle lens. For Quan Huafu 135 SLR camera, the lens with focal length below 16mm and viewing angle around 180 degrees can be called "fisheye lens".

The characteristics of fisheye lens are as follows: a. The viewing angle is large and the shooting range is extremely wide. B. the sense of perspective is greatly exaggerated. C. The fisheye lens is severely deformed, but it can achieve dramatic effect. D. It is very expensive, originally designed for astrophotography. E. The first lens protrudes outward, so the usual filter cannot be used, and instead it is a "built-in filter".

5. Refractive lens (reflective lens):

It is a super telephoto lens. It looks short and fat, and its weight is much lighter. It is more suitable for hand-held shooting. The lens structure is simple and the imaging quality is excellent. The disadvantage is that there is only one aperture, so it is not convenient to control the depth of field. When the camera takes a view, the view is dark and it is not convenient to focus. At present, most of the catadioptric lenses popular on the market are made in Russia, and their prices are low. Common focal lengths are 500mm and 1000mm, which is one of the good choices for users who are short of money and like telephoto.

Zoom lens: refers to a lens whose focal length can be adjusted freely within a certain range.

1. Type of zoom lens:

A. manual focusing and autofocus. According to different focusing methods, zoom lenses can be divided into manual zoom lenses and automatic zoom lenses.

B. zoom range. Generally speaking, 20-40mm is called wide-angle zoom lens, 35-70mm is called standard zoom lens, 70-200mm is called long-distance zoom lens, and 200-500 is called telephoto zoom lens. Of course, there are also many lenses covering the range from wide angle to medium focus or even telephoto, such as 28-200mm and 28-300mm.

C. zoom ratio. From the zoom magnification, there are 2 times (such as 35-70mm), 3 times (such as 70-2 10mm), 5 times (28- 135mm), 7 times (28-200mm) and 10 times (50-0 times). Generally speaking, the larger the zoom range, the larger the volume, the lower the image quality and the smaller the aperture.

D. zoom mode. According to different operations, it can be divided into push-pull zoom and rotary zoom. The advantage of push-pull zoom is that it is easy to use, and it can quickly zoom from the farthest end to the nearest end. The disadvantage is that the lens is easy to slide when shooting in pitch. The advantage of rotary zoom is that the focus ring and zoom ring are independent, and the rotary operation does not interfere with each other. But the operation is not as simple as push-pull zoom, especially when "zoom shooting explosion effect" is adopted, it is not as easy to realize as push-pull zoom.

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