Hasselblad Planar 80mm f/2.8: Inconsistent flash via PC Sync

Discussion in 'Medium Format' started by patrick_regan|1, Dec 2, 2016.

  1. Hi all,
    Are there any obvious/simple reasons why I'd have inconsistent flash triggering with the PC Sync port on my 80mm f/2.8 Planar lens? About every second or third trigger of the shutter results in no flash firing. It seems to be more prevalent at the faster shutter durations, but only slightly; I get inconsistent flash firing at every shutter speed from bulb to 1/500.
    I'm having zero issue with my 150mm f/4 Sonnar lens. I get consistent flash firing every time. This makes me think the issue is part of the lens' shutter mechanism, and not part of the camera body's shutter triggering mechanism. But I won't rule out any culprit just yet. I admittedly have very little knowledge of how these lenses are constructed (mechanically).
    Just looking for any tips, ideas, thoughts on what might be an obvious culprit or a simple fix before I shell out to have the lens CLAed.
    Thanks!
     
  2. Sounds like you figured it out....probally is the lens.
     
  3. PC sync sockets are inconsistent per se, as electrically unreliable as they are, but if your cable is working fine with other lenses and the socket on the 80mm doesn't look more corroded, it is probably CLA time. - I have a focal plane shutter of that kind in a second 35mm beater now.
     
  4. Early versions of the lens likely use a Compur shutter while late production versions probably use Copal shutters.
    The contacts consist of the PC socket outer contact contacting the shutter case via the mount nut with the center contact made by a brass or copper contact that gets pressed against the center contact of the PC socket. At some point Compur switched to a metal resembling chrome plating or polished silver that tarnishes much slower than brass or copper.
    The solution is to disassemble the shutter and clean/polish the contacts and reassemble.
     
  5. Synchro Compur flash sync contacts as used in the larger and later versions of the shutter, should be the same or similar to your shuttered lens on the left, smaller version used on Rolleiflex Planar f2.8 lens on the right.
    Contact at the red arrow.
    00eGBL-566704184.jpg
     
  6. I on the other hand, suspect your sync cord. Specifically the tip, it might be very slightly out of round and not a snug
    enough fit for that lens. Try another sync cord (I always keep three with me) or use a rubber band to hold it in place.
    Sync cables are the weakest link in the proverbial chain .
     
  7. Because you aren't experiencing the problem with your 150mm lens, but only with your 80mm lens, I would suspect that your 80mm lens is the older, C type lens. If so, I would bet money that the flash terminal on your lens, (the part that you plug your flash cord plug into), is worn, which is why the shutter is only firing your flash intermittently. Unfortunately, the flash terminals for the older C lenses are no longer available.
    www.david-odess.com
     
  8. "the flash terminal on your lens, (the part that you plug your flash cord plug into" David O.
    I agree with David's explanation that the PC terminal is a point of heavy wear and therefore may be the main source of the sporadic issue.

    But let me add that the 'sync contact spring' has a very high potential for wear & tear (It's flexing with every firing of the shutter regardless of the any flash usage). This means that either a fatigue-flex or fatigue-crack can form, which likely changes the (illustrated by Charles M's image) "min. 0.5 mm" tolerance.

    Plus, it may be as simple as a possible carbon formation on the sync contact spring 'points'. This can certainly create an intermittent contact (Flashes with high trigger voltages can micro-spark at the 'points' when they're actually in use).
     
  9. Gus, you are correct, in that the "sync contact spring", more commonly referred to as the "internal flash contact", does flex every time the shutter is fired, and, after many thousands of firings, will break. However, up until the time that it breaks, it will make an electrical connection each and every time. After it breaks, there will be no connection at all, so no flash. In my 40 years of servicing Hasselblads, I have never seen or heard of an intermittent flash problem being due to the internal flash contact, as there is never any carbon formation on the part. Basically, if the internal flash contact is not broken, it will not be the cause of intermittent flash. Once broken, there will be no flash.
     

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