Buying a used lens... quick tests or things to look for?

Discussion in 'Digital Photography' started by VirtualRain, Mar 3, 2010.

  1. VirtualRain macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #1
    I'm meeting a seller off CL tomorrow to purchase a Canon EFS 10-22mm UWA lens.

    I'll have my camera with me and will take a few shots to ensure it's focusing accurately. Besides that and a physical inspection, is there anything I should be looking for?

    Thanks!
     
  2. Phrasikleia macrumors 601

    Phrasikleia

    Joined:
    Feb 24, 2008
    Location:
    Over there------->
    #2
    Listen to the motor to make sure it doesn't have a grinding sound. Check to make sure the rings move smoothly. Otherwise, if it seems to focus reasonably well, then there's not much else you can do. When you get home you should put it on a tripod and do some more controlled focusing and sharpness tests, but that will be for your own knowledge at that point.
     
  3. OreoCookie macrumors 68030

    Joined:
    Apr 14, 2001
    Location:
    Sendai, Japan
    #3
    The lens is too young to have some sort of fungus.
    Check whether there is any dirt in the optical pathway. This will pretty much not affect image quality at all (since the dirt is far, far, far away from the focal plane), but it is an indication of usage. Also, you may get a discount.

    As Phrasikleia said, check the mechanics. I'd do some quick test at open and closed aperture and various focal lengths. Equivalently, you could also ask the seller to send you a few RAWs.

    Personally, I bought all of my lenses used and have fared very well with it. Not once did I have problems with the lens afterwards.

    Perhaps one more thing that may or may not be important: I have a sensitive sense of smell. I'd ask if the previous owner was a smoker or not. I've bought a flash from a smoker (and I didn't ask whether the owner was a smoker nor did he indicate it). I've spent one afternoon cleaning the flash three or four times with rubbing alcohol and I've washed the case in the washing machine. I'd ask. Obviously this does not affect optical performance, but I prefer to buy from non-smokers.
     
  4. jampat macrumors 6502a

    Joined:
    Mar 17, 2008
    #4
    Probably not as important with that lens (due to the relatively small aperture), but taking along a focus test block never hurts.

    http://focustestchart.com/focus10.pdf

    Each lens and body has a tolerance and if they both lean the same direction, a particular lens may not like your body (front or back focus issues). Obviously if you have a 50D or 5Dii, this can be easily corrected and you don't care.

    As setting up tripods at a restaurant is difficult, I sit the camera on one table and the test block on another one.

    Have fun with that lens, it can take some really interesting pictures.
     
  5. toxic macrumors 68000

    Joined:
    Nov 9, 2008
    #5
    - unless you're getting a good deal, avoid dust behind the rear element.
    - make sure the sharpness is reasonly even across the frame - if one side is significantly softer or distorted, the lens is decentered
    - to check focus, take pictures of real subjects. it's too easy to screw up with a test chart. Canon's recommended testing length is focal length * 50.
     
  6. VirtualRain thread starter macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
  7. maddagascar macrumors regular

    Joined:
    Oct 26, 2009
    #7
    didn't want to start a new thread, but i've been looking at used lens online at craigslist..it's a 28-135mm lens kit for canon which is 3.5-5.6 IS..would that pretty much be the same as my lens kit including image quality besides the focal length?
     
  8. audioteknika macrumors regular

    Joined:
    Mar 4, 2008
    #8
    This lens has mediocre optics. Don't get your hopes too high.
    Still, if you buy it used, I think it's a good deal.
     
  9. neutrino23 macrumors 68000

    Joined:
    Feb 14, 2003
    Location:
    SF Bay area
    #9
    The 28-135 does OK at 135 and gets softer towards 28mm.
     

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