hasselblad light seals.

Discussion in 'Medium Format Cameras and Accessories' started by dainmcgowan, Jun 10, 2010.

  1. dainmcgowan

    dainmcgowan Member

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  2. sandermarijn

    sandermarijn Member

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    I have. The seals work well, although they are not entirely indentical to the ones Hasselblad themselves use.

    The original ones have a piece of curved metal underneath the mylar (if this is mylar at all). This metal strip pushes the foam upwards against the magazine cover, thus creating a light lock.

    This one from ebay does not have a metal strip underneath mylar but relies solely on the expanding properties of the (slightly thicker than original I think) foam to form the seal.

    I am sure both methods work equally well. I myself did cut off a piece of the foam because I felt it didn't fit as well as it should. But maybe that's just me.

    I could show you pictures but that would require opening up my backs and I'd rather keep them in their current state.

    Maybe you can order original H'blad seals- those would be (much?) more expensive I'm sure.
     
  3. sandermarijn

    sandermarijn Member

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    This is a useful link. It provides replacement instructions.
     
  4. Q.G.

    Q.G. Inactive

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    "Blackbird" is a decent guy.
    Though his foams may not be original ones, that should not be a problem (i cut my own too).

    The more difficult bit to 'recreate', find an alternative for, is the foil. I don't know whether the ones this seller is offering are originals or not. If not, i would sure like to know where he gets the material from, because i would love to be able to make my foils mysefl too!

    You do not have to change the foil, by the way, unless it is damaged. It's the foam bit (not mylar, Sander) that with time deteriorates.
    So keep using the foil, and try to make your own foams too!

    I use a sheet of black fine, closed-cell foam, i bought at a hobby/crafts shop (for fellow dutchman, Sander: i got it at the local Pipoos. You should be able to find some). I'm not sure what it is called in English, but the stuff is called Moosgummi (moss rubber) in German. It's listed as Crepla rubber.
    I forgot what i paid for it when i got it, but it's now listed at 0.9 Euros for a 20x30 cm sheet.
    I guess i paid the same. Good for very, very many foams!
     
  5. w9cae

    w9cae Member

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    I replaced some foam seals by using felt with sticky back. You can buy at most craft stores & it does come in various thickness. Having said this I am not familiar with Hasselblad. But thinking creatively can come up with a light box seal solution.
     
  6. sandermarijn

    sandermarijn Member

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    I think you misread my post.

    Incidentally, in my second-hand back the original Hasselblad 'mylar' was torn, while the foam was still fine. Don't ask me why ;-)
     
  7. sandermarijn

    sandermarijn Member

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    Thanks for the tip Q.G.

    Some sources say that the light seals must be replaced every year, which seems a bit excessive to me. In case of amateurs like me, ten years sounds more reasonable.

    I will check out that shop in ten years :rolleyes:

    Wonderful site, your "Hasselblad Historical", Q.G.- I've used it for dating lenses and for the replacing of the light seals. Very useful.
     
  8. Q.G.

    Q.G. Inactive

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    That rings true. Sorry!

    I have had that happen myself. The foam gets changed regularly. But the foil does not.
    So when the foil does 'go', odds are good that the foam inside are not yet too old.



    I bet you you will not. You will be looking for new seals much, much sooner.

    The thing with the foam is that it's not wear through use only that makes it go bad.
    One thing that hastens its demise is being compressed a lot (so when the magazine is not in use, store it with the slide out).
    I don't know which is worse: being used a lot (lots of time with no slide compressing the foam, but lots of times that slides get inserted too) or only sparingly (lots of time that the foam is kept compressed - even though you migth store the magazine with slide out, you can't do that when there is film in the magazine. So unless you run through a roll completely the day you put it in, the slide will be in).

    The other thing is pure and simple ageing. The foam will go bad all by itself.


    So no matter what we do, no matter whether professional or not, the foam needs replacing regularly.
    Unless two things: one is that you would not care if you get light leaks on your film, since you do not need them to earn an income. The second is that you will not be using the camera at all for very long periods. Then you would only need to put new seals in every once in a long while, when you want to give the thing a go again.
    :wink:


    So change seals regularly!
    I do very often (did so again last night, in fact), since it is a quick and easy job, and the stuff i use is so incredibly cheap.

    It's not my site; it's a cooperative effort, a community thing.
    The people behind it are listed at the bottom of the "about" HasHis page.

    But on behalf of us all: thanks!
     
  9. sandermarijn

    sandermarijn Member

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    I just went for a rainy bike ride (the brain seems more active then) and realised basically the same thing myself: light seals go to gue regardless of use, so no reason to assume that the amateur will have to replace less often than the hard-working professional.

    That said, I do have (non-Hasselblad) cameras twenty years old whose seals are still perfectly fine and cushiony. The opening and closing of these cameras' backs should not be dissimilar to the insertion of the dark slide in a Hasselblad magazine. There may be different qualities of foam of course (not saying that Hasselblad foam is crap though!).

    I guess I'm one of those silly amateurs who only replace their foam after they've lost a roll of once-in-a-lifetime pictures. Honestly, I'm too cheap to be deserving of a Hasselblad :sad:

    Actually I do have a question that is not totally off-topic:

    After I replaced the light seals of my second-hand A12 (from marktplaats.nl), I put it into the strong April-sun for an hour or so, with the orientation of the slit and the earth's rotation making sure that the light seal got *the* ultimate test. I did this with (otherwise) blank frames of 400 ASA film, and for several frames, varying slightly the orientation of the camera frame to frame.
    Some of these frames showed (very) slight fog. Very slight is a subjective qualification, but let me assure you that it was very slight indeed :wink:

    Is this normal for a 'good' back? I am not really worried about it in real life, it's just that imperfection bothers me. Should a light seal be 100% tight? Or more like 99.99%? Academic maybe, but I'm curious (which is also an academic thing, yes).
     
  10. Q.G.

    Q.G. Inactive

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    Well... I tend to think that maybe it is. :surprised:

    We would want it to be 100%, but i certainly never assume it is.
    So my gut feeling: 99.99% sounds more realistic.

    Maybe i should seek the help of a psychotherapist, but i do worry about it.
    Or rather (no psychotherapist required after all, i think), i don't really worry, but don't take a chance either.
    I hate leaving stuff with light (and temperature) sensitive other stuff inside exposed to very bright light.
    So while i do keep an eye on how sunlight hits the dark slide slot, and try to prevent that happening, i have no qualms about using the thing in bright sunlight. But it goes back into the bag, or my self-produced shade, as soon as it doesn't need to be exposed to sunlight any longer.
     
  11. sandermarijn

    sandermarijn Member

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    Confession: I tape the slot when the sun is out strongly. Help is on its way. I hope. Maybe.
     
  12. bdial

    bdial Subscriber

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    I recently had similar problem to sandermarijn's where the darkslide caught the mylar and shoved it into the magazine in front of the film.
    Even with that it didn't leak much, I just had an outline of the seal on my negatives. A very annoying failure, because I couldn't insert the slide enough to remove the magazine.

    I wasn't sure which ebay sellers of light seals were ok so I called Hasselblad USA, and found out they could sell me seals for about 1$ more than the ebay sellers, and they showed up in the mail the next day.

    So far, I've not found the mythical sheets of suitable foam in a hobby store, but Hasselblad made it reasonably painless to get replacements.
     
  13. Theo43

    Theo43 Member

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    On the matter of an alternative material to replace the foil, I have something in hand that looks promising. It is the pouch that held the coffee pack for the little coffee maker in the hotel room where we stayed recently. This pouch is a laminate of foil and plastic, seems to have appropriate stiffness, and, most important, resists tearing. There must be other things, perhaps medicinal patches, that are packaged with foil-plastic laminate material. Since all my seals are newly installed I won't be trying this any time soon, but if others do I hope they will let us know how it worked.
     
  14. Willie Jan

    Willie Jan Member

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    the problem with light seals occure faster when you put away the camera with the darkslide in the back. If you leave the back onto the camera and the darkslide is out, the seal will stay longer healthy.
     
  15. PVia

    PVia Member

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    I tried a seal kit from eBay and didn't have much luck, it still leaked but not as bad, so I sent the back to David Odess.
     
  16. Andrew Moxom

    Andrew Moxom Member

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    These seals are okay, but go with OEM ones. What you don't get with this cheaper kit is a foil strip on the foam that the OEM ones do have. If you use IR film, it will likely fog without the foil strip... Trust me how I know. If you change them every other year, the OEM ones are perfect....
     
  17. BrianShaw

    BrianShaw Member

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    I, personally speaking, probably wouldn't use it for my Hassy, but I have for other cameras...

    One of the mythical foams is brand named "Foamies" and is available in 2mm thickness, with or without stick-um on one side. The sheets are something like 6 sq inches, maybe 8. They come in a myriad of colors, but I've only used black. Best source is not a hobby shop, but an arts-and-crafts shop like Michael's or JoAnn Fabric.

    Perhaps there are other mythical foams, too!
     
  18. Q.G.

    Q.G. Inactive

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    What can and will happen with OEM seals too is that the foams you get are old.
    New old stock is no good when these thingies are concerned.
    You think you're back is fine because you just put freshly acquired foam in it. But the acquisition being fresh does not necessarily mean that the foam too is fresh.

    One more reason why i like to cut my own.

    And i'm happy to be able to report that those mythical foams are very real, and really should not be hard to find. :wink:


    The foil strip below the foam pad, Andrew, is not there to seal the slot against IR. It doesn't reach up far enough to seal the slot. It's there to push the foam up. A "blade spring", if you will.
     
  19. Andrew Moxom

    Andrew Moxom Member

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    Well the OEM does not fog IR film the cheapy ones do... The only difference is the foil. Just saying.
     
  20. Q.G.

    Q.G. Inactive

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    I'm not disputing that, Andrew.
    But it could be something else that is responsible, could it not?