How to buy second-hand lenses (turn)

The appearance inspection method is basically the same as that of the fuselage. As long as there are no serious bumps, normal mechanical properties, no mildew, flowers, cracks and oil leakage in the lens, there will generally be no major problems. The imaging quality can only be judged by real shooting. If you are a careful person, paying attention to the camera is also a lot of "learning". First of all, look at the brand: there are more lens manufacturers than fuselage manufacturers, including the original factory and professional lens factory, with strong technology and high ability. Each manufacturer has its own sheep head and dog head. Who should I choose for the ordinary lens? Which one looks good? Choose that! Professional lens selection should be rational, don't turn eight times, and finally find your son, so tired. When designing professional lenses, manufacturers are very different from ordinary lenses in terms of intentions, materials and durability. Different manufacturers and grades of second-hand lenses have a great influence on their future use. Have you noticed that in recent years, the lenses produced by some manufacturers have developed in optics, improved in technology, shrunk in volume, increased in focal ratio, decreased in materials, lingered in phase quality, declined in durability and increased in awards? The new lens is still like this, and the second-hand lens is not cheap! Check whether the second-hand lenses have a maintenance history. In addition to referring to the inspection method of the camera, it should be noted that some screws are hidden under the rubber zoom ring, and some can only be found by rotating or pushing and pulling with the hood. If the rubber ring of the lens is too loose, it means it has been uncovered. You can observe the double-port clasp in front of the camera and check the internal clasp, screws, etc. In the process of adjustment and zooming. The repaired lens will leave traces in some places. Be careful of some lenses with ordinary colors, but the inside is clean and abnormal, zoom and zoom damping are too large. Maybe they have been repaired or polished. For repaired lenses, as long as they are not too bad, they should not be rejected, especially for heads with good reputation. When choosing a second-hand lens, you should carefully check the aperture blade. There are problems such as rust spots, deformation and greasy, which may make the blade run slowly and affect its future use. Most MF lenses can reduce the lever through the aperture to check whether the aperture blades are flexible and natural, and whether they can return quickly every time they are dialed. Some autofocus lenses must be installed and tested. The aperture adjustment device of the lens should be clearly identifiable. The focus accuracy is checked together with the fuselage. Zoom ring and focus ring damp the feel, and it is normal that MF lens is larger than AF lens. The zoom rings (push-pull and double-ring rotary) of individual zoom lenses are seriously loose and slippery, which will bring trouble to practical use. Please pay attention. Regarding the dust, bubbles and scratches on the coating, try to face the outdoor bright light, change the focal length, rotate the focusing ring, and check carefully before and after. Found dust and bubbles. If it is serious, it is definitely not good. Generally, 95% of second-hand lenses are less than new ones, and some dust or coatings are slightly scratched, so don't worry too much, because it won't affect the imaging quality. Bubble problem is not the patent of second-hand lens, but it is brought out from the womb. There are not many professional shots, which usually appear in miscellaneous or amateur shots. It's hard to say whether you like it or not. You can only do it yourself. Moldy spots and fog are the taboos of the lens. Any mold and fog in the lens will affect the imaging. Even though the area was small at that time, it developed and spread rapidly. Moldy lenses are mainly early single-layer coated lenses and some lenses before 1990s, including some manufacturers with low coating technology. The climate in the south and offshore areas is sometimes a little careless. Ten days later, a shot will be covered with "pine branches", and the film friends in the north can't take it lightly. When cameras and lenses are bought home, it is very troublesome to find problems, and stores are generally reluctant to return them. So at this time, you should negotiate with the store and try to reach an agreement with the store on the "warranty period". The longer the better. Most stores will say, "Try to take a roll within a week and bring it back if there is a problem." This problematic "problem" should be stated in advance and must not be vague to avoid future quarrels. A good shopkeeper will not "bite his teeth" on the issues discussed in advance. Get the machine and lens to test. Every function of the fuselage, every segment of the lens and every aperture must be carefully tested and recorded. The best way to test the lens is to use a tripod, choose a good film and an advanced developing shop to get an accurate and fair conclusion. Don't use high-sensitivity inferior film, shoot it by hand at will, and develop it cheaply, which may discount good-quality lenses and cameras and make them invisible. Never compare the original factory with the non-original factory, focusing and zooming, and the new with the old. This is unfair and unrealistic. Finally, remind the film friends who bought the second-hand camera to play with the camera and lens as much as possible within the agreed time, and it is best that there is no problem. If you find that there is something wrong with the lens or the imaging is not good, please take the so-called "evidence" immediately and inform it quickly or go directly to the store to solve it. Don't just talk and don't do it as "nothing happened"