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Faulty eBay SMC Pentax-M 50mm f2 lens - repair or return?

Discussion in 'Lens Matters' started by john_g, Feb 27, 2009.

  1. john_g

    john_g Well-Known Member

    Today I received a supposedly fully-operational SMC Pentax-M 50mm f2 lens but it has sticky aperture blades and stops down too slowly to work correctly. In all other respects it's fine and a quick test shows how sharp it is compared to my kit lens.

    I reckon I got it cheaply (£11 + postage), so I'm undecided about whether to return it or risk trying to repair it. I'm generally pretty good with mechanical stuff but haven't tried anything like this before and I'm worried about it releasing loads of tiny springs or ball-bearings!

    Is it relatively simple to repair a lens such as this or should I just return it, bearing in mind that I assume a replacement would cost a fair bit more? Cost is a big factor at the moment and I don't particularly mind that it's an M rather than an A lens, nor that it's the f2 rather than the f1.7.

  2. Malcolm_Stewart

    Malcolm_Stewart Well-Known Member

    Give David Boyle a call.

    He's at the Camera Repair Workshop in Milton Keynes, and sorted out a Contax lens with similar problems. Camera Repair WS
  3. Roger_Provins

    Roger_Provins Well-Known Member

    Over the years I've cleaned many lens diaphragm blades to make them work properly. Some say it's possible to do the job with only partial disassembly and wiping the blades with cotton buds. However I've found it's almost always necessary to completely remove the blades and clean them individually - remember they must be totally clean and absolutely dry. Quite a fiddly and long winded job and lot of work on a £11 lens. :(
  4. spangler

    spangler Well-Known Member

    Use it with a coupling ring reversed onto a telephoto lens for macro work.

    Andrew :)
  5. nimbus

    nimbus Well-Known Member

    Personally I would return it, since it is not as described, add what you have paid to the cost of making it fit for purpose and the total will be more than the cost of a fully functioning example.
  6. Benchista

    Benchista Which Tyler

    Personally, i would return it and get an f1.7 instead...
  7. Wheelu

    Wheelu Well-Known Member

    Me too. I bought an f1.7 with a working ME Super body attached for circa £25, maybe prices have escalated a bit since ;)
  8. Mojo_66

    Mojo_66 Well-Known Member

    If the seller agrees to reimburse you for postage as well as the cost of the lens then send it back. If not it's probably not worth the hassle and I'd be tempted to to have a go at the repair for the price you paid for it.
  9. tazio35

    tazio35 Well-Known Member

    As mentioned above, you probably won't get the postage back, so have a go at fixing it yourself. Or, shoot everything wide open and enjoy the shallow depth of field. Great for portraits; I have exactly that lens myself.
  10. john_g

    john_g Well-Known Member

    Thanks for the replies.

    I tried the lens again yesterday and, when cooled down to the outside ambient temperature, it really didn't want to stop down at all.

    I've emailed the seller, requesting a refund.
  11. john_g

    john_g Well-Known Member

    Latest news: I've just received a full refund from the seller. His attitude has been helpful throughout and, having received the lens back, he agrees that it is sticky. So, nothing lost, nothing gained, but at least my faith in eBay is still intact.

    By the way, I had an opportunity to try a Pentax-A 35mm f2.8 the other day and found that it was marginally less sharp than my 18-55mm kits lens, which surprised me.

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