Olympus OM Prism Foam Problem

Discussion in '35mm Cameras and Accessories' started by BruceN, Aug 22, 2005.

  1. BruceN

    BruceN Member

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    I just discovered this. Does anyone know which models are affected? Is it only the OM-1's and 2's, or are the newer 1n and 2n models affected as well?

    Thanks,

    Bruce
     
  2. Andy K

    Andy K Member

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    Whats the problem?
     
  3. knutb

    knutb Member

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  4. Woolliscroft

    Woolliscroft Member

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    I have a house full of OMs and have never seen this problem. My 1 and 2s are all the n models, so maybe they aren't affected.

    David.
     
  5. BruceN

    BruceN Member

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    I think it's one of those things that is just a matter of time. They can last longer in some climates, etc., but if the foam is in there it WILL eventually deteriorate and take the silver off the prism. I have 4 OM's and none of them have had this happen, but I don't want to take the chance. I have a friend that has an OM-1 this has happened to - it doesn't affect the image on film, just drives you crazy when you look through the viewfinder.
     
  6. resummerfield

    resummerfield Subscriber

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    The Nikon F has the same problem with the Plain Prism. Some are worse than others, I guess depending on how they were stored. If you start to see the slightest visible effect in the pentaprism, I would replace the foam. Otherwise, wait for a "scheduled" trip to the repair shop.
     
  7. JHannon

    JHannon Member

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    My Mamiya M645 prism had a similar problem. The foam's adhesive ate away at the mirror finish right in the middle of the viewing area. I removed the rest of the foam and attached a small mirror piece facing in to the prism. It works but you can see a slight band. The only other way is to have the prism re-mirrored. (I don't know if this is possible.)

    It should be a lot easier to have the mirror replaced on your OM.

    It is probably best to have the foam replaced before it turns to tar and effects the mirror surfaces.
     
  8. BruceN

    BruceN Member

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    I understand that the fix for the OM's is to simply clean out the old foam and reassemble the camera. Apparently they put the foam in to keep outside light from reaching the sensors near the viewfinder, but the consensus is that the top covers are light tight enough that the foam isn't necessary.


    I just ordered a set of the nice OM tools from Beljan Mfg. I think I'll do my beater OM-2n myself, and if that goes well I'll do the others myself, too.
     
  9. clogz

    clogz Subscriber

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    Bruce,
    Have you got the website for Beljan?
    Thanks in advance
    Hans
     
  10. BruceN

    BruceN Member

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  11. BruceN

    BruceN Member

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    I have my answer!

    The 1n's and 2n's ARE affected by the prism foam. I received my tool set from Beljan today and (in between rediculous political sniping in the soap box) performed the operation on my beater OM-2n. It went remarkably well, and I'll be doing the rest of my OM bodies soon. I can't say enough good about Joe Beljan's OM tool set, it's probably the best $40 I've spent on ebay in quite awhile. (usual disclaimer: I have no financial interests with Beljan Mfg.)

    Bruce
     
  12. John Hermanson

    John Hermanson Member

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    OM-1 foam

    OM-1's (chrome) were produced with prism foam up to approximate serial serial number of about 1,110,000. Above that number (and continuing to where the 1N chrome started) they were produced without prism foam. MANY old OM-1 bodies show deteriorated prism foam by dark green or black blotches in the viewfinder. Once a blotch shows up, it means the old foam has turned to goo and eaten through the paint and aluminum coating on the prism. The only rela fix is to replace the prism. OM-1 Black were also made with prism foam up to the same serial number. Unfortunately, ALL 1N bodies were made WITH prism foam. Hope this helps!
     
  13. Xmas

    Xmas Member

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    This is an old thread...
    But inaccurate the old damaged prism can just be cleaned and replaced you won't notice any difference.
    Use a soft plastic tool to flick off damaged paint and coating if you DIY.

    The magic is called total internal reflection.

    Best to do it this decade rather than delay.
     
  14. klownshed

    klownshed Member

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    There's another option too... The prisms from double-digit OMs are the same as for the OM-1 and 2 and were never fitted with foam. A 'spares or repair' OM-10 makes for a good, cheap prism donor.
     
  15. Xmas

    Xmas Member

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    They don't always swap...
     
  16. GRHazelton

    GRHazelton Subscriber

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    Blankety blank Foam

    Amazing that Olympus and many other makers used and continue to use that %^*(*&*)_(( foam! Wouldn't black felt have done the job? Light seals on backs. Grrrrr..... Back in the day the back/body juncture used a light trap. Was it that expensive?? Should have been a one-time design expense, and perhaps better manufacturing tolerances. And again the hinge area could use black felt.

    Sorry, I'm feeling my years this Monday.:devil:

    But I suppose that the digital revolution takes care of this problem, 'cept for those of us who shoot both. Lovin' my film gear, expecting a Bronica S2a in the mail today. Yummy! Company for the YashicaMat and the Pentax 645n.
     
  17. thuggins

    thuggins Member

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    Do not go thru the time, expense and trouble to find a "donor" prism as a replacement. What you are seeing in the viewfinder is not the lost silvering; it is the damaged silvering still sticking to the prism and edge of the remaining silvering. Remove the the old, gunky foam from the camera (a bit of a messy job). Then remove any damaged silvering from the prism and clean the area and feather the edge of the good silvering using Simichrome or toothpaste. The view thru the viewfinder will look like new.

    I have done this repair a couple of times and it works every bit as well as putting in a pristine prism.
     
  18. anfenglin

    anfenglin Member

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    I once substituted the prism of an OM-1 with one of a broken OM-10. Works like a charm.
     
  19. darinwc

    darinwc Subscriber

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    That's really good info that the prism can be made good without replacement. I have a box of parts cameras that I have pulled prisms from. Feel kinda bad but they gave some other good parts as well.
     
  20. albada

    albada Member

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    I have put prisms from OM-10s into several OM-1s. They always fit perfectly. I've never seen an OM-10 with foam over the prism, so they were always good.

    OM-10s are also a good source of split-image-type focusing screens for OM-1s. They fit, but lack the little tab for holding, so one must take extra care when handling them.

    Mark Overton
     
  21. xtolsniffer

    xtolsniffer Member

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    It's a pretty simple job if you can get the winding lever off, just be careful of dropping old foam down between the prism and the viewfinder, then you have more dismantling to do to get rid of it. Sometimes the wind-on levers really don't want to shift though.
     
  22. wblynch

    wblynch Member

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    I've used the OM-10 screens myself and they are wonderful.

    But once I got it in with the wrong surface out and after a couple rolls of missed focus shots I finally figured it out.