How does KOMERY choose a camera lens?

If you can't find a physical store, you can buy it online and choose a lens with the right price and function according to your own needs.

Matters needing attention when choosing a lens:

First, the appearance inspection

1. 1. Check whether the lens packaging box is bumped or squeezed, and whether there is paint stripping and decoloration;

2. Open the box and check the accessories (such as hood and lens cover). ) The purchased lenses should be all complete.

3. Check the lens number (whether the product numbers on the lens, warranty card and factory card are consistent).

4. Check the lens entity for signs of trauma (such as bumps and scratches) and the smell of new lenses.

5, check the bayonet, etc.

The human eye is the most perfect and advanced instrument. For the detachable single-lens reflex camera lens, first install the lens on the fuselage to see whether the lens bayonet is well matched and loose, and various functions (such as internal metering, TTL automatic flash, autofocus, etc. ) can be played normally.

Step 6 check the aperture

Turn the aperture ring, and each gear should be positioned accurately, clearly and freely; Smooth holes should be regular polygons, such as hexagon, octagon and nonagon.

7. Look at the glass

Open the aperture and look forward from the lens tailstock against the strong light, and you can clearly see the inside of the lens. The interior of brand-name lenses should be clean and dust-free, and the glass texture should be pure, without bubbles and cracks.

Open the front and back covers of the lens and take the lens to a well-lit place. If you manually turn the lens to the maximum aperture, aim the lens at the light source and check whether there are scratches, bubbles or obvious dust particles on the optical glass inside the lens.

8. Listen to the sound

Shake the lens gently, except for the slight noise of the aperture, there should be no "ding dong" sound from loosening the lens.

9. Feeling

When focusing in zoom, the hand feel should be smooth, with appropriate "damping feeling" and not too "loose" (except when focusing manually with AF lens). Manually adjust the zoom ring and focus ring, and check whether there is strong friction, looseness or abnormal noise when rotating or pushing and pulling.

10, install the lens on the fuselage, and check whether the autofocus is accurate and fast, and whether there is abnormal noise during focusing.

Comprehensive: the lens should be free of bubbles, dust and mildew, and the lens coating should be free of scars; There are many colors (red, yellow, blue, etc. ) on the surface of the lens, which means that it is multi-coated. If there is only blue light, then the lens can't be multi-coated. The aperture is fresh, the blades are not rusted, and the focusing ring is flexible and uniform; When the zoom lens is placed vertically, the push-pull ring should not slide down by itself; The lens shell is exquisite, with smooth surface and no scratches.

Second, focus accuracy check?

When checking, place a piece of ground glass with appropriate size at the exposure window of the camera so that the ground glass faces forward and clings to the plane of the exposure window, then open the B or T door of the camera to view the lens resolution pattern or newspaper posted on the wall. Move the camera back and forth at the same time until the image formed on the ground glass is clear. Finally, measure the distance between the camera exposure window plane and the resolution pattern or newspaper with a ruler. If the measurement result is equal to the focal length value adjusted on the lens, it shows that the focusing accuracy of the lens is high; On the contrary, it is low.

When checking whether the zoom lens is distorted, zoom the lens to each focal length value and check whether each focal length value is distorted or not in turn.

Third, pay attention to check whether the four corners of the picture are blocked.

When checking, install the camera lens on the camera and narrow the aperture, you can find bright objects with uniform illumination and focus on them. From the viewfinder, you can observe whether the four corners of the picture are blocked, and the normal lens is not blocked.

When inspecting the zoom lens, adjust the focal length of the lens to various focal length values for inspection, and observe whether the four corners are slightly blocked at each focal length value.

Fourth, pay attention to check the imaging deformation.

During inspection, the camera lens should be installed on a single-lens reflex camera or a direct camera, and whether the horizontal or vertical lines at close range are deformed can be observed through the viewfinder. If the horizontal line or vertical line of the object at the edge of the picture becomes arc, it means that there is distortion aberration in this lens. The greater the linear deformation, the more serious the distortion phenomenon.

Look at the camera in the shop window. If the square line is bent after imaging, the lens is deformed. In general, wide-angle lens has barrel distortion; The telephoto lens has occipital shadow distortion; There should be no obvious distortion in the standard lens.

When checking the focusing accuracy of an object at infinity, the focal length of the lens should be adjusted to the infinity mark to see whether the image on the frosted glass plate is the clearest; If it is clear, it means that the focusing accuracy is high; If the definition is poor, it means that the focusing accuracy of the lens is low.

Verb (abbreviation for verb) checks the uniformity of lighting in the image field?

Most of the defects of uneven illumination in the image field are on the short-focus lens. Therefore, when buying a short-focus photographic lens, it should be installed on the corresponding single-lens reflex camera. Through the viewfinder of the camera, the brightness of the center of the picture is exactly the same as that of the four corners. If the center is bright and the corners are dark, it means that the illumination of the image field is uneven, and the image taken by such a lens has a high center density and a low corner density.

Sixth, check the recognition rate?

Observing the scene from the viewfinder, when the focus is right and the edge line of the scene is very clear, the recognition rate of the lens is high; If it looks blurred, even red or blue double lines appear, then the lens dispersion is serious and the discrimination rate is poor.

Seven, check the stray light coefficient?

It's sunny, neither smokeless nor foggy. If you use the viewfinder to observe the scenery, there is always a gray feeling, indicating that the lens is mixed and the quality is not good. If the scene seen in the viewfinder is transparent and clear, the lens quality is good.

Eight, check the color reproduction

The color restoration of the lens is very important for taking bright and realistic photos. To check the color reproduction, first remove the lens from the fuselage, remove the lens cover, adjust the aperture to the maximum, put a piece of white paper behind the lens, and point it at the fluorescent lamp in the store to see if the fluorescent lamp projected on the white paper after the lens is as white as before. This difference is very small, you have to observe it carefully to see it. If the color difference is large, it means that the color reproduction is poor and the quality is inferior.

Expand:

Advantages: 1 This machine is small, light and easy to carry. 2. There are many accessories, which are affordable and cost-effective. What kind of bike do you need? The shooting effect of the machine is still good, which can be seen clearly on the computer. 4. Simple and easy to use, reasonable key position and convenient external equipment. 5. The zoom distance is far, and the fill light can change color, which is practical enough. 6. The display screen can be flipped and touched, and the display effect is clear. 7. The anti-shake effect without zooming is OK.

Disadvantages: 1 The touch of the buttons is lacking and the experience is slightly poor. 2. The quality control of accessories needs to be strengthened, otherwise it will affect the use experience. 3. The content that can be set in the machine menu is less, and the playability is biased. 4. Applications connected to 4. WiFi can't be downloaded, which affects the use.