Buying second-hand lenses
Authors: Goran Katić and Marina Ćosić
As well as there are things you have to look out for when you shop for a used photo camera, there are things you have to look out for when you shop for a used lens. Here are a few tips:
1. Check the general state of the camera
Like with a photo camera, simply by looking at the lens in general you should be able to see and judge its state. If you see the color pealed off on some areas that means the lens is quite used.
2. Look out for scratches
As previously mentioned, the color peeled of the lens can say something about the camera; however, it does not play a huge role in the quality and sharpness of the photographs. The glasses of the lens do. If you point the lens toward the strong source of light and look trough it, try to notice if there are any big damages on a surface of the glass, like big scratches. If you do notice something like it, my suggestions is that you do not consider buying that lens because to repair it would be too expensive. Scratches like these create blurry parts on the photograph because they turn the light away which then unevenly falls down on the negative or a chip and reduces the sharpness in that area of the photo. One more thing to look out for is a net look-alike subtle structure or something that looks like little proper channels on the inside ends of the lens. That is the fungus which affects the contrast and sharpness. It can also spread out to the other lenses if continued to be kept in the humid place.
3. …and dents too!
I have seen many lenses with dents on it's filter thread which probably means the lens was dropped and the sharpening mechanism is not working properly (like it happed to me once ).
4. Double-check the state of the rings
Are the zoom and sharpening rings always supposed to function smoothly? YES! If they don't, they are obviously dusty and greasy and need to be professionally cleaned which will cost you more money and effort. When looking at the lens also pay attention to the rubber on the rings, see if it’s worn out or falling off. Sometimes the heath will deform the rubber which will make it very hard or even impossible to focus.
5. AF and MF commands
Be sure to check if the AF and MF commands are moving smoothly and working properly but be careful they don't move too smoothly or too easy, as in that case they can sometimes switch without you noticing.
6. Screws
Check if the lens has all the screws needed, and the back lens thread is not too scratched or looks overused.
7. Auto focus check
As the next step you should attach the lens to the camera and try focusing random objects placed in a different distance and check the accuracy of the auto-focus.
8. Test the shutter
The same as the lens thread, the shutter thread should run smoothly. Remember one small detail though. The newest cameras don’t have the shutter thread, so when testing use the DOF button on your camera.
9. Gledajte kroz objektiv prema jakom izvoru svjetla. Tako možete vidjeti da li ima ikakvih ogrebotina, prašine… Ako primijetite nekakvu finu, mrežastu strukturu ili pravilne kanaliće na unutrašnjim rubovima leća, uz objektiv ste dobili i gljivice. Gljivice koje utječu na kontrast i oštrinu preko zraka mogu prijeći i na druge objektive. Takav objektiv je čuvan na vrlo vlažnom i toplom mjestu, i nipošto ga nemojte kupiti, koliko god njegova cijena bila prihvatljiva.
10. The test with the newspaper
One last way to test your lens can, actually, be done in two ways. One way is to do the MTF test which is very complicated and/or the other way is to apply a simple test with a newspaper. We suggest the simpler one, of course. All you are going to need for this last test is, of course, the newspaper, any wall, one tripod and a little bit of a tape. Take the newspaper with a big title, smaller subtitle, the text and tape it on the wall as straight as possible. Then set up your camera and take a few pictures, each one with a different shutter value…
