How to check if old zoom lens still works?

Discussion in 'Adapted Lenses' started by thatp, May 28, 2010.

  1. thatp

    thatp Mu-43 Rookie

    11
    May 27, 2010
    Bangkok
    Hi,

    I would appreciate it if anyone could guide me step-by-step on how to check if an old manual-focus, zoom lens, in this case, a Carl Zeiss Jena MC Macro Zoom 28-70mm, still works. The problem: this particular piece of glass is attached to a broken Minolta XD7 (which means I cannot load a roll of film into the camera and shoot in order to find out).

    Having never handled 1970s-era automatic film SLR before, I looked into the viewfinder and saw split-circles type focusing aid. On the lens body, there are one aperture setting ring, one zoom ring and one focus ring.

    I need to make sure this lens is still in working order before I place an order for Minolta MD MC lens adapter for my E-P2.

    Many thanks.

    [​IMG]
     
  2. mauve

    mauve Mu-43 Top Veteran

    892
    Mar 9, 2010
    Paris, France
    I'd bet my shirt this is a tamron or sigma made zoom branded by Zeiss. The aperture is a giveaway, I've got the same in OM mount from Tamron.

    This said, it's a very good lens, very sharp. My 'holiday snapshot' zoom for years. Macro should be 1:4, not stellar but comes handy sometimes.

    To check it : first, set the aperture to smallest (22) and find the lever commanding the mechanism on the mount. Press and release it a few time : aperture blades should move without delay nor 'catch'. Then open wide, find the brightest lamp you have, and shine it through the lens. Check for defects in the glass ; web like etching : throw the lens away as far as you can, it's fungus, it can contaminate your other lenses by contact, and this one zoom is not worth enough to salvage it. Other defects are less important. Small particles are invisible unless you got a full bag of sand trapped inside, and even defects on the front are barely visible (because a lens desn't focus on itself).

    Otherwise, it should be sound.
     
  3. thatp

    thatp Mu-43 Rookie

    11
    May 27, 2010
    Bangkok
    :2thumbs:Thank you, mauve, for your very helpful advice. I decided to ditch it after having detected traces of fungal contamination deep inside the lens. Now I know how to separate the wheat from the chaff with a certain measure of confidence.
    Another quick question, if you don't mind: Is there any type of fungal infection that is very difficult to detect with naked eyes?
    The reason I'm asking, I'm still on the lookout for an affordable manual focus lenses.
    You can't be too careful, right?
     
  4. mauve

    mauve Mu-43 Top Veteran

    892
    Mar 9, 2010
    Paris, France
    Sadly, yes. Trouble is most fungal infections begin on the sides of the lens barrel, and then proceed to grow and ultimately reach the glass some times after. So you may have an infected lens and no mean to know it until it reaches some glass surface. Be very very careful to the outside circle of the lenses, and hope for the best. The fungus problem is even more pervasive in pump type zooms, because they "vacuum" external atmosphere in operation, bringing all kind of nasty spores inside the lens. Lenses operated by rotation are less subject to this.

    Storage considerations : most fungus are very sensitive to UV. To prevent, stop, and sometimes kill lens fungus, it's best to store lenses outside of their pouches, without end caps, in a dry sunny place. Do not attach them to a body especially a cloth shutter RF.

    OTOH, enclosing cameras and lenses in leather pouches for storage is a contributing factor to fungus spreading. Leather is still animal skin, and brings infection in, plus it keeps humidity and warmth trapped in obscurity : perfect petri dish, but bad photography idea.
     
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