Pentax 67 90mm LS CLA

Discussion in 'Medium Format' started by dave_cheng|1, Oct 7, 2005.

  1. Just purchased a used 90mm LS from eBay. Everything appears working
    fine. The lens was described as in excellent condition at a 9 out of
    10. Well, it's more like a 7 or 8 the most. It was described as clean
    and no scratch. I clearly see an object of 2mm by 0.5mm inside under
    the front glass. Shined with a flash light I saw a bit of dust inside
    as well. I am not too worried about those tiny dusts but the thing
    that's 2xx long and 0.5mm wide near the center of the glass really
    bothers me.
    I really should contact the seller to ask to return it. But I wonder
    how much it may cost to have the front glasses cla'ed. I don't need to
    clean anything else but the front element to get rid of that thing. I
    am not really sure what it is. It's not fungus nor scratch. Can the
    name ring be unscrewed to get to the front element like all Pentax
    35mm lenses? It is tempting to get it done myself. I have done repair
    of a Pentax 135mm for my Spotmatic before. This should be a lot easier
    as I do not need to do anything beneath the front elements. How do you
    guys think? Should I send it to Colorado? I know I should send it back
    to the seller. What a hassel! This is the worst purchase from Ebay I
  2. WJT

    WJT Moderator

    I would try to get a refund from the seller. If that is a dead end then post the guy's name so others won't get burned. The "Bay" has so much of this crap it is sickening. Regards.
  3. It turned out that the speck inside the lens is a piece of dust larger than I can tolerate. Took the lens to a local professional camera repair shop. I was told it would take more than $100 to just do a CLA for the front elements only. They warned about the need of optical alignment after the CLA. Well, the $100 (or more) charge may be reasonable but the need of optical alignment is really just BS.

    I unscrewed the name ring quite easily. After careful examination I figured out how to dismantle the front group of glasses. It is a sealed group of glasses came out as a whole. After taking it out the speck I disliked together with some other smaller dusts were right on the bottom surface of the front group. A few blow of my duster took care of them all. The front group of glasses went back to where it came out with no adjustment possible. Optical alignment? How? There is only one way in and there is no room for error. Cleaned all metal parts and reinstalled everything in reverse order.

    Sprayed a coat of TLC (thinfilm cleaner) on the front surface of the glass and wiped it dry by using a microfiber cloth. The glass is as clean as I like. The CLA is done. Found that the shutter ring becomes much lighter to cock than before the CLA. It was a bit heavier and I was concerned that it might be a problem developing. After the CLA it feels just great.

    BTW, the seller offered to take it back and gave me full refund including shipping charges. I don't think he deliberately sells it with a speck in it. So I decide to accept the lens and pursue a CLA route. I now have a clean working 90mm LS.

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