In my previous post about buying second hand gear, I discussed what to look out for when getting camera bodies. I will now go on with what to check for lenses.
1. As per camera bodies, you should first check the overall condition of the lens. Any obvious marks or dents should be taken note of, assuming the owner has not already informed you. Dents or large scratch marks may indicate that the lens has been dropped before. Lenses are generally not as sturdy as camera bodies, obviously due to the fact that the glass elements inside may be jarred out of alignment, or worse, cracked due to the impact.
2. Move the focus and zoom rings, if any. These should be smooth, though the amount of dampening depends on the grade of lens. You won’t expect a kit lens focus ring to feel as buttery smooth as the one from a Zeiss Manual Lenses. The aperture ring, if present, should be smooth to turn/adjust and clicky (unless it is a Cine lens which has been “declicked”).
3. Check for any “play” in the lens components. Lens designs vary, but generally there should be very little movement when you try to shift each lens component.
4. Look through the lens and check the optical elements for any signs of fungus or scratches. Your tolerance may vary, but I generally do not bother with heavily scratched or fungused lenses.
5. Mount the lens on your camera. The camera should not yield any error messages or explode (just kidding).
6. Check the Autofocus, make sure the lens is able to focus on both near and far objects. Unless you are trying this in low light, the AF should be smooth, it may or may not be fast, however. Also, note the type of AF motor the lens uses, the old school micromotors and the screw drive motors found in Nikon lenses can be quite noisy. I generally find USM/ AFS/SWM lenses to be squeaky quiet. You can hear the lens in a quiet environment, but you won’t be that bothered by it.
7. Check the VR/IS/OS/VC. The viewfinder generally jerks once the stabilisation kicks in. What results is a very stable shot which means the lens has negated your handshake movement.
8. Make sure the aperture closes properly. I see this problem with fully electronic lenses like those from Canon, where the contacts are dirty or damaged and the lens is unable to close the aperture completely. Check by using aperture priority and taking shots with different aperture values.
9. Lastly, check for AF issues or calibration issues. Higher end bodies tend to be able to perform AF fine tuning. This allows any lens calibration issues to be somewhat nullified. However, check with your manufacturers if unsure. The problem usually manifests itself with front or back focusing. You can go to your camera’s AF fine tune menu option to do the necessary changes.
After all the checks are done, pay the chap/lady and enjoy your new lens. 🙂
Let me know if there are any checks that I missed here.