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Flash cord for older lenses converting to modern flash
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AuthorMessage
ktm_2000
Joined: 19 Jun 2019
Posts: 75
PostPosted: Fri Jan 22, 2021 3:12 pm   Post subject: Flash cord for older lenses converting to modern flash

Hi All,

Since we all are cooped up, inside shots with flash are a bit more important. My newer large format lenses with the single small flash post work fine using a connector cord to connect to my flash transmitter.

My older bipost shutters are a different story.


I did a chat session with B&H photo people and ordered a cable "Paramount Bipost to B".
https://www.bhphotovideo.com/c/product/164971-REG/Paramount_PMBPPF_Female_PC_to_Bipost.html

When I received the cable, it plugs in fine to the bipost on the older lens but the other end is a male type connector. I can plug that into a standard flash cable and daisy chain it to the flash transmitter but it doesn't work, as soon as I connect it, the flash fires and keeps firing every 20 seconds or so.

If I reset the flash, it will stop flashing every 20 seconds but triggering the shutter does not get the flash to go.

Suggestions of what I can get to use flash with the older shutters?
45PSS
Joined: 28 Sep 2001
Posts: 4081
PostPosted: Fri Jan 22, 2021 9:25 pm

What shutter or shutters does this happen with? Some may have the flash sync shorted until the shutter is cocked.

You may have a bad BiPost cable.
45PSS
Joined: 28 Sep 2001
Posts: 4081
PostPosted: Sat Jan 23, 2021 4:38 am

DUH
It just dawned on me that on some shutters one pin of the BiPost is connected to the shutter case and is therefore ground or common.
Try turning the cable at the Bi Post 180°.
ktm_2000
Joined: 19 Jun 2019
Posts: 75
PostPosted: Tue Jan 26, 2021 2:25 pm

Your second theory of being hooked up backwards makes a lot of sense but in testing with 2 different lenses it didn't make a bit of difference.

I'm now thinking your first theory of a bad cable is more accurate, I've got to track down my multimeter to confirm it.
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