Cupping across 8x10 Fidelity holder

Discussion in 'Large Format' started by john_mcdonald, Apr 29, 2003.

  1. I have a few Fidelity 8x10 holders. Today as I pulled a dark slide,
    I noticed that a holder had a convex cupping across its width at
    the end where the slide enters. I sighted across all of my Fidelity
    holders, and was surprised to find that they all had a
    pronounced cupping. No problems or light leaks at all, but I was
    just curious if others have noticed this feature—perhaps it is
    inherent to the design. I suppose the springs of the camera back
    flatten the cupping when the holder is in the camera to make the
    opening light tight.
     
  2. I pulled out a new double box of 8x10 Fidelity holders to check them and they do have a slight outward "cupping" in the portion that accepts the darkslide. Squeeze on the outside of the holder against the high center of this cup and you will see how little applied pressure allows it to return to center. Like you commented, I have to believe that this was designed purposefully to be affected by the spring back of the camera once the holder is inserted. No big deal.
     
  3. John,

    As Michael said - no big deal as long as the holder is 'light tight' the camera springs
    should take up the slack. I've had some pretty old holders and find the 8x10 plastic
    ones always have that 'bend'. I've noticed even 5x7s have an ever so slight bow to
    them.

    Cheers,
    Roger...
     
  4. If it does become a problem (and I have Fidelity holders, and it's not a problem for me), I've seen some holders that have an interesting modification to prevent this. The owner had a channel routed into the holder at the lock-rib end and a metal strip screwed in on each side to keep the light trap perfectly flat.
     
  5. Yes, this is "normal." The lighttrap that protects the darkslide slot is a long
    fabric covered spring, the pressure of this spring pushes against the front
    plate of the holder causing BOWING in the middle. ("cupping" would describe
    a concavity) In VERY large holders this is a cause for concern, because the
    darkslide springs are not always strong enough to flatten the holder against
    the back of the camera.
     

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