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How to Grade Pentax Lenses

by Max Cooper
  • Overview

    Pentax has a long history of making superb lenses, and their recent digital cameras retain backward compatibility, making "legacy" lenses a viable alternative to brand-new models. Older lenses provide a great bargain and a retro look, but whether you're buying or selling, evaluating a lens's condition is the first step to getting the best value.
    Used Pentax lenses make excellent alternatives to new models.
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  • Step 1

    Establish a grading system. KEH.com, an online retailer of used cameras and lenses, grades items from "new" and "excellent" to "bargain" and "ugly." Whatever system you use, each flaw you find in the lens should take its rating down a notch.
  • Step 2

    Check the focusing action of the lens. Fit the lens to a camera body and focus on subjects near and far. The lens should focus smoothly, with no evidence of dirt in the action. The image in the viewfinder should appear clear and sharp at your focal point.
  • Step 3

    Investigate the focus further by pointing the camera at a brick wall and looking through the viewfinder. Are the lines between the bricks sharp? Can you see details in their texture? Finally, is the image uniformly sharp in all areas, or is one side sharper than another?
  • Step 4

    Evaluate the general condition of the lens. Is it dusty or covered in fingerprints? Does it come with the original owner's manual, paperwork and packaging? Take these things into account when grading the lens.
  • Step 5

    Remove the lens from the camera and hold it under a bright light. Are there scratches on the glass or the lens barrel? Minor scratches will not impact image quality, but they may depreciate the price a lens will fetch.
  • Step 6

    Turn the aperture ring while looking into the front element. Check for consistent aperture-to-iris coordination: the iris should expand or contract with each click of the aperture ring.
  • Step 7

    Make sure the aperture blades are free of dirt and oil.
  • Step 8

    Open the aperture to its widest setting and look through the rear element at a bright light. Check for fungus and haze. Pay close attention to the edges of the lens. Some dust is normal.
  • Step 9

    Check for filter ring damage by visually inspecting the front of the lens. If possible, install an appropriate filter and make sure it threads correctly.
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  • Pentax lens Compatible camera body
  • Pentax lens
  • Compatible camera body
  • If possible, shoot some photos with a prospective lens and closely inspect them. Full-resolution images from a digital camera, or large prints from a film camera, will betray flaws in the lens that can't be seen through the viewfinder.
  • If possible, shoot some photos with a prospective lens and closely inspect them. Full-resolution images from a digital camera, or large prints from a film camera, will betray flaws in the lens that can't be seen through the viewfinder.

References & Resources