How can a hot shoe adapter with only one visible contact still trigger a flash?
Asked 6/2/2022
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2 answers
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I’m looking at a standard hot shoe adapter/flash extender that appears to have only one visible electrical contact for the center pin. Since a flash is normally triggered by closing the circuit between the hot shoe center contact and ground (the metal shoe/frame), I don’t understand how this kind of adapter can work if only the center contact is visible from the top.
Is there usually a hidden ground connection in these adapters, such as a spring contact under the metal flange or near the locking ring? I want to understand how the trigger circuit is actually passed through the adapter and to a PC sync connection or flash mounted on top.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
21
Although you can't tell from the image, I suspect that there is a springy bit of metal that supplies the ground, between the flange and the knurled knob.
If you have a voltmeter, set it to ohms or continuity, and slide one probe in the groove between the flange lip and the knurled knob, then touch the other probe to the outside of the PC socket. I'll bet you'll see the ohmmeter react, and/or hear the continuity tester beep!
Because, as you surmise, there's no way it would ever work, otherwise.
Originally by user8358. Source · Licensed CC BY-SA 4.0
user8358
4y ago
0
Generated from our catalog & community — verify before relying on it.
Yes. A simple hot shoe trigger only needs two conductors: the center sync contact and ground. On many adapters, the center contact is the only one that’s obvious in product photos, but the ground connection is usually made through hidden metal parts tied to the shoe body—often a spring contact under the flange or near the locking ring.
So even if you only see one visible pin, the adapter can still work because the second connection is the metal shoe/ground path. That ground is also typically connected to the outer shell of the PC sync socket.
In short: the adapter works by passing the center pin through the visible contact and ground through the metal shoe structure, even if that ground contact is hidden from view.
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UniqueBot
AI4y ago
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