The height of the camera lens

Answer:

6, check the stray light coefficient The weather is eyeny, neither smoke nor fog, if the viewfinder in the view of the scene always some gray feeling, then the lens stray light, the quality is not good; such as in the viewfinder to see the scenery transparent, very clear, Note that the lens is of good quality. 7, check the color reproduction The color reproduction of the lens is very important to shoot a vivid picture. To check the color reproduction, first remove the lens from the fuselage, remove the lens cover, the aperture open to the maximum, take a piece of white paper on the back of the camera, facing the store's fluorescent lamp, see through the lens after the projection to the white Whether the fluorescent lamp on the paper or the original white, not color cast. This difference is very small, to be carefully observed to see. If there is a big difference in color, indicating poor color reproduction, quality times. ????In summary, it is a relatively strict detection system, and if it is second-hand camera or lens, do not have to be so harsh, for the above items, the seller can promise no problem, it OK!

4, the uniformity of the field illumination inspection Like the field illumination uneven defects, the vast majority of the lens in the short focus. Therefore, in the purchase of short-focus distance camera lens, should be installed to the corresponding single-lens reflex camera, facing the brightness of the object, through the camera's viewfinder to observe the center of the screen and the four corners of the brightness is exactly the same. If the center is bright and dark four corners, indicating that the field illumination is not uniform, so that the lens shot out of the image center density, four corners density. 5, check the identification rate From the viewfinder to observe the scene, when the focus is good, the edge of the scene is very clear, the lens of the high rate of discrimination; if it looks vague, or even red or blue double line, then the lens dispersion is serious, poor identification rate.

2, pay attention to check whether the four corners of the screen have been blocked defects Check the camera lens will be installed on the camera, and the aperture shrink, the contrast of the bright objects to view the scene, focusing, from the viewfinder to observe the four corners of the screen is blocked, the normal lens is no blocking phenomenon. Check the zoom lens, the lens should be adjusted to the focal length of each focal length to check to see whether the various focal lengths of the four corners were slightly occluded phenomenon. 3. Note the inspection of the imaging deformation In the inspection, the camera lens should be installed in a single-lens reflex camera or direct viewfinder camera, through the viewfinder to observe the distance of the horizontal lines or vertical lines with or without deformation. If the object line at the edge of the horizontal line or vertical lines into an arc, indicating that the lens there is distortion aberration. The greater the deformation of the straight line, indicating that the more serious distortion. The camera facing the direction of the shop window to see, such as the square of the line after the formation of a bend, indicating that the lens distortion. Under normal circumstances, wide-angle lens barrel distortion; telephoto lens with occipital distortion; standard lens should not have a more obvious distortion. For the infinity of the subject of the focus of the accuracy of the inspection, the lens should be adjusted to the infinity of the infinity mark to see if the frosted glass on the knot is the most clear; if clear, said the focus is high; Degree is poor, then the focus of the lens focus is low.

?The lens surface can be a variety of colors (red, yellow, blue, etc.), that is multi-layer coating, if only blue Yingying monochromatic light, no lens, no lens, no lens, Then the lens can not be multi-layer coating; aperture block fresh, no rust blade, focusing ring flexible uniform; zoom lens erect placed, the push ring should not slide; lens shell fine, smooth surface, no scratches The Second, the physical condition: 1, the focus of the inspection Check the appropriate amount of frosted glass placed in the exposure window of the camera, so that frosted face forward, and close to the exposure window plane, and then open the camera's B or T door, on the wall of the lens solution Image pattern or newspaper for framing. At the same time, move the position of the camera back and forth until the image formed on the frosted glass is clear, and finally use the ruler to measure the distance between the plane of the window and the resolution pattern or newspaper. If the result of the measurement is equal to the focal length adjusted on the lens, the focusing accuracy of the lens is high and vice versa. When checking the distortion of the zoom lens is the problem, the lens should be zoomed to the various focal lengths, respectively, in order to check the various focal lengths at or without distortion aberration.

? ?Precautions: How to pick the camera with the naked eye. Select the lens head should be selected from the following aspects: First, the appearance: 1, the lens has no paint decolorization phenomenon; 2, the lens should be attached to the accessories (such as hood, lens sets, etc.) is complete. 3, check the lens number (lens, warranty card, the factory card on the product number is the same) 4, check the bayonet. Whether the lens mount is perfect, not loose, the various functions (such as measuring light, TTL auto flash, auto focus, etc.) can play properly. 5, look at the glass. Check whether the lens inside the optical glass has scratches, bubbles, or obvious dust particles