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Thread: Compur Shutter and Strobe firing at slow shutter speeds

  1. #1
    NCAmother's Avatar
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    Compur Shutter and Strobe firing at slow shutter speeds

    I have a compur 2 shutter firing into profoto strobes question: When dropping my shutter speed to slower than 1/30s, the flash is triggered multiple times. I.E. the flash will fire twice wether at 1/30s or 1 second. Is this normal? Am I able to drag the shutter while using strobe? Thanks,
    Nate

  2. #2

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    The shutter contacts are bouncing. They close, firing your strobe, but then bounce open again and because your new strobe is ready almost immediately, unlike older power packs, it fires again when the contacts close again to stay closed as long as the shutter is open. This is quite common with Compurs and Seikos. There is no demand for my Ghostmaster Flash Fire Control System for Leaf Shutter Cameras so I no longer produce them. A "bounce free switch" circuit in these pretty well tamed this problem and added many other capabilities. You will learn a lot from my now public domain patent.
    http://www.freepatentsonline.com/5530320.html

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Quote Originally Posted by Neal Chaves View Post
    The shutter contacts are bouncing. They close, firing your strobe, but then bounce open again and because your new strobe is ready almost immediately, unlike older power packs, it fires again when the contacts close again to stay closed as long as the shutter is open. This is quite common with Compurs and Seikos. There is no demand for my Ghostmaster Flash Fire Control System for Leaf Shutter Cameras so I no longer produce them. A "bounce free switch" circuit in these pretty well tamed this problem and added many other capabilities. You will learn a lot from my now public domain patent.
    http://www.freepatentsonline.com/5530320.html
    Thank you. I wish I could purchase, was still available. Is there any thing my lens/shutter repair woman (Flutotscamera)can do to eliminate this problem?

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Think I need something like that for my Packard shutter, it's giving me multiple flashes too.

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    You don't need all the functions of the Ghostmaster, just a bounce-free circuit in the sync connection. I'll get out the books tomorrow and find a schematic for a circuit that will work. It's going to tame the double pops, but will probably limit the top sync speed to 1/125 as on the Ghostmaster. The Compur 2 is kind of unique in that it operates on B from the cable release without having to cock the shutter each time. Have you tried using B? It might not have the bounce problem. Because I have seen this on new shutters, I doubt a CLA will change anything.

    Packards I have seen use a common micro switch. Some of these are snap action, some are plain SPST type like a push button. I can see where the snap action type might be prone to bouncing.

  6. #6

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    https://circuitdigest.com/electronic...bounce-circuit

    At the above link I found there are now ICs you can buy to rig up a switch debouncer very easily if you have some electronic skills, but I had a better idea come to me overnight. Just sync through an inexpensive radio trigger set. I bought the ones I am using for the Open Studio workshops we used to have before sheltering in place for $5 each at Roberts. These things won't sync at over 1/125 sec. so they are not going pop on a bounce.

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Clean the contacts first... If there is a imperfect connection when internal contacts are closed, they can miss or multiple fire... Most old plated contacts will be oxidized...

    Steve K

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    NCAmother's Avatar
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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Quote Originally Posted by Neal Chaves View Post
    https://circuitdigest.com/electronic...bounce-circuit

    At the above link I found there are now ICs you can buy to rig up a switch debouncer very easily if you have some electronic skills, but I had a better idea come to me overnight. Just sync through an inexpensive radio trigger set. I bought the ones I am using for the Open Studio workshops we used to have before sheltering in place for $5 each at Roberts. These things won't sync at over 1/125 sec. so they are not going pop on a bounce.
    Hi Neal, I just picked up the GhostFlash off of eBay, I got lucky it was listed. Iíll keep you updated on how things work out

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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Quote Originally Posted by NCAmother View Post
    Hi Neal, I just picked up the GhostFlash off of eBay, I got lucky it was listed. I’ll keep you updated on how things work out
    If you didn't get an instruction book with it, let me know.

  10. #10
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    Re: Compur Shutter and Strobe firing at slow shutter speeds

    Quote Originally Posted by Neal Chaves View Post
    If you didn't get an instruction book with it, let me know.
    Thanks it came in yesterday. Iím very pleased as it for the most part resolved the multi flash problem on instant mode, however on delay mode I still get the multi flash at 1/5 second and slower. On B it wil flash just once which is great. Iím running a Compur shutter to pc/mono plug to GhostMaster to pc outlet to remote hotshoe with profoto remote trigger to profoto B10 strobe.

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