Help Buying Used Lens

[Cricketboy]

The other day while looking through an antique shop with my uncle I stopped by the camera area to see if I could find any lenses that fit the k1000. I got lucky and found one! I'm pretty sure it's 35mm - 70mm or 100mm, with very nice hard carrying case. $39.95 for it. The aperture ring moved all the way up and down and changed the iris, focus ring worked, zoom worked, and the optics were spotless. Is there anything in particular that I should check/watch out for when looking at a used lens? Should I bring the camera to the store and put it onto the camera and see if it functions?

 

[tirediron]

Buying used lenses is a great way to save money and get better gear than you normally would. All but two of my lenses have been bought used with nary a problem.

Always make sure that you review the lens on-line especially if it's somethin gmore on the unusual side. Like cars, some lenses are prone to certain issue, and knowing what to look for ahead of time can save you a lot of grief. As well, know what prices are common, check eBay, used gear stores etc.

When you first meet with the seller, look at the lens carefully. What is the condition of the exterior? Is is scraped or scratched? Is the filter-ring damaged (always ensure you know what diameter filter the lens takes and bring a filter with you). If a filter won't screw on easily, question the seller, it's usually a good indication that the lens has been dropped or banged hard. The price should reflect this ('though I would likely walk away at this point).

Ensure you have a small penlight and look through the lens from both ends; look for any odd refractions which might indication displacement or separation of internal elements or fungus growing inside (not uncommon in older lenses). A little internal dust is nothing to worry about. Hold the light against each end element at various angles to look for cleaning damange, scuffs, swirl-marks etc. Again, I would walk away if there are any; this is an indication someone didn't know how to care for the lens.

Close the aperture (if you don't already, check to ensure you know which pin on the lens operates the aperture) and watch it carefully. When you let the pin go, it should snap back quickly and evenly; look for any signs of oil or residue on the blades. When they're closed, do they form an even pattern, or do one or more appear to not be in the same position? If so, you know what to do here.

Smell the lens carefully. Sound funny? Probably, BUT if a lens has been stored somewhere damp (especially an older lens) you may smell a damp, moldy/mildew smell. Again, you know what to do if you thing there's any indication of that.
Mount the lens on your camera; ensure that it functions correctly in ALL modes, take and CHECK test shots in manual mode at all apertures. Mount and unmount the lens several times, ensuring that it feels smooth and doesn't catch. Manually focus the lens and operate the aperture ring (if so fitted) if it's a zoom, operate that. These functions should feel smooth and positive. If there's slop, grinding, or points at which something feels wrong, walk away. Ensure you do this with the camera in normal shooting position, upside down, lens pointed up, down, etc. often a problem can manifest itself in one position and not in others.

 

[sobolik]

The other day while looking through an antique shop with my uncle I stopped by the camera area to see if I could find any lenses that fit the k1000. I got lucky and found one! I'm pretty sure it's 35mm - 70mm or 100mm, with very nice hard carrying case. $39.95 for it. The aperture ring moved all the way up and down and changed the iris, focus ring worked, zoom worked, and the optics were spotless. Is there anything in particular that I should check/watch out for when looking at a used lens? Should I bring the camera to the store and put it onto the camera and see if it functions?

If the lens has no electrical circuitry in it what you did is the proper examination. Your naked eye and spinning of rings etc is adequate for a K1000 era lens.
See this link to demonstrate that if you can't see any glass problems then it aint worth worrying about the glass. Dirty lens article

Electrical circuitry in a lens requires trust (like eBay reputation) or trying it out.