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Apr 09

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Tips on buying a used lens

I had been looking around for a second hand Tamron 17-50mm F/2.8 lens for a while now. So when a seemingly too good to resist offer came up, I jumped upon it. However, I let my excitement get the better of me and almost ended up with a paperweight that looked like a lens. It's not that I didn't know what to look out for (I just got overexcited), so below are some tips to keep in mind when buying a used lens. In this post, I'll only cover lenses which you can personally inspect. General tips:
  • Never part with any money before even meeting up with the seller.
  • Ideally, meet during the day. If you have to meet at night, then make sure that the location is well lit. This allows for easier inspection of the lens.
  • Take your time and be prepared to spend at least half an hour testing the lens.
  • If the seller isn't prepared to spare you the time to test the lens properly, then you'd best look for another seller.
  • If you're new to photography and interchangeable lenses, bring a more experienced friend to help out.
  • Ask questions. If the seller is being evasive, something may be amiss.
  • Be calm (don't get overexcited like me). This will allow you to objectively judge the value of the lens.
  • Personal safety is paramount, all usual safety tips apply.
  • Lastly, trust your gut instinct.
What to look out for in a lens:
  • Check the lens' physical condition: dents, scratches and dust in tiny nooks and crannies all point to a well used lens (if more than a year old) or a careless owner (if less than a year old).
  • Does the lens come with its original packaging and accessories? Again, missing items may point to an owner who is less than careful with his equipment. If the lens is being sold without most of its accessories, it may even be a stolen item.
  • Check for scratches on any elements. Tiny scratches probably won't affect the final image.
  • Check for dust in the lens. Some lenses, especially lenses that have front barrels that move in and out as you zoom tend to suck dust in. Again, tiny amounts of dust won't affect the final image.
  • Check for fungus. Fungus indicates the lens wasn't stored properly. Cleaning out fungus on lens elements can be costly and sometimes the damage is severe enough that the special coatings on the lens elements are eaten away by the fungus.
  • Check the lens' mechanical aspects. Does it zoom properly? Is the focus ring smooth? Are the aperture blades moving smoothly? Does it communicate properly with the camera you're using?
  • Snap a couple of photos at various settings and review the resulting images. Are the images appearing as expected? Is there something odd?
  • If your camera's LCD is too tiny (like mine) or doesn't help much when checking for critical sharpness, bring a laptop along to check the images.
  • Check for severe front or back focusing. There's a pretty comprehensive set of instructions (including a test chart to print and use) here. You won't have time to accurately perform the test described, but you can probably manage a quick and dirty one. Most lenses will have a front/back focus issue. It just depends on how much you're willing to live with. Plus, most higher end bodies can be front/back focus calibrated to suit specific lenses.
  • If the lens doesn't have an aperture ring, then make sure the aperture is at its smallest opening when the lens isn't mounted on the camera. Anything otherwise may indicate a fault with the aperture (this is the mistake I made). If it has an aperture ring, then make sure that the aperture is behaving as it should when you rotate it.
  • Check to see if the aperture is stopping down properly. If you have a DOF preview on your DSLR, use it. If you don't, you can still probably test it out manually by using a fixed shutter speed but varying your aperture. The resulting image should change in brightness.
  • If the lens has anti-shake built in, check to see if it's working. Toggle between on and off, snap an image at a slow shutter, etc.
  • Lastly, trust your gut instinct.
I don't think the above is a comprehensive list, but it covers the essentials. What about the Tamron you ask? I'll write about it in another post! 😉  

Permanent link to this article: http://blog.stillworx.com/2011/04/09/tips-on-buying-a-used-lens/

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