Why does my Canon 30D sync inconsistently with a Speedlite 340EX?
Asked 4/2/2011
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2 answers
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My Canon 30D has started showing inconsistent flash sync with a Speedlite 340EX. About half the time part of the frame is not lit by the flash, and the affected area varies: sometimes the top, sometimes the bottom, and sometimes the whole frame misses flash.
I’ve already tried:
- manual and E-TTL modes
- different shutter speeds, even as slow as 1/30s
- second-curtain sync on and off
- high-speed sync on and off
- checking the hot shoe and flash contacts, which look clean
The camera’s built-in flash works normally. I also tested the 340EX on a Canon 20D, and it seems to work fine there.
What could cause this kind of intermittent flash-sync problem on the 30D?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
5
Sounds like you've gone through a variety of troubleshooting steps - if you can't discern any sort of pattern or consistency in the errant behavior, it might be a problem with the flash. If you have a friend with a Canon camera, see how the flash behaves on his unit - or perhaps bring it down to your favorite camera store and see if they'd let you test it out on another body.
Originally by user89. Source · Licensed CC BY-SA 4.0
user89
15y ago
0
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Because the built-in flash works normally and the 340EX seems to behave on a different body, the likely issue is the connection or flash-sync behavior between that specific 30D and flash rather than a general exposure setting.
Since you’ve already ruled out shutter speed, E-TTL/manual, second-curtain, and HSS settings, the next useful step is cross-testing: try the flash on another Canon body and/or try another compatible flash on your 30D. That helps confirm whether the fault is in the flash, the camera hot shoe, or the interaction between them.
An intermittent partial-frame flash exposure usually points to a sync/communication problem rather than normal metering. Even if the contacts look fine, the hot shoe or flash foot could still have an intermittent electrical issue.
If repeated cross-testing shows the 340EX only misbehaves on the 30D, the camera body likely needs inspection. If the 340EX starts showing the same behavior elsewhere, the flash is the more likely culprit.
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