Hasselblad filter fitting too loose - help

Discussion in 'Medium Format' started by pavelkupcik, Jan 31, 2021.

  1. I have a Bay70 Hasselblad polarizer that's fitting too loose when screwed onto the lens, meaning it unscrews way to easily where accidental dismount is likely. When I compare it to my other filters, the three tabs on the inside of the filter are not bent, unlike my other filters that fit snugly. I tried to press the tabs, they bent under my finger but when I let go they bent right back to its original position - perfectly horizontal with the filter. So, any advice how to go about bending the tabs permanently or any other tricks? Maybe I'll put the tabs gently in a strong clamp or vice for few days. Thoughts?
  2. Take a pencil, or similar soft thingy (something that gives a bit when resistance becomes that great that the tabs might break. No guarantee that they will not break, but it offers a small margin), and push the tabs gently but firmly towards the rim. That will tighten the fit. It is the recommended way, and it works.

    It doesn't work permanently, as in: forever. Unless you leave the filter on. But a polarizer will be taken off and put on again many times, and each time the tabs will be pushed back a bit. You can reapply the above fix. But only for so many times before the tabs do break.
    Last edited: Jan 31, 2021
  3. I just tried with the pencil, but the pin just bounces back. Now I'm trying something different, I put it inside a clamp that's holding the pin bent, I'll let it sit overnight and see if it helps.

    If it did work though, you're saying it would stay that way longer if the filter stayed attached - how is that possible? The bent pin presses against the filter thread, basically clamping it, I would imagine that staying in the clamping position would make it slowly lose its force as the filter thread is pushing against it, and it would eventually unbent. Thank you.
  4. Being under constant strain will not do much. It will not bend the pin back to its original position, nor will it cause fatigue. It's repeated cycles of strain and release that will cause fatigue and eventually break the tabs. And each time you put the filter on, it might bend the tab back a little bit.

    So putting the thing in a vice for a while will not help. It just wastes a bit of your time. Either the force applied is great enough to bend the metal instead of merely flexing it, and then it will be instantly. Or it is not, and keeping it under pressure will not be enough to deform the tabs. It will just keep it flexed, ready to flex back again when the pressure is released.
    So forget about keeping it bent overnight, and apply enough force, in the right place (not at the loose end of the tab), to actually bend it.
  5. It worked this time with the pencil. Instead of pushing just the end of the tab I pressed with the pencil and moved up and down the tab multiple times with a lot of pressure. Now hopefully it stays that way for a while. Thank you for the advice.

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