Why do I get a black band at the bottom of the frame when using radio flash triggers?
Asked 4/22/2015
5 views
2 answers
0
I’m new to off-camera flash and started seeing a black band across the bottom half of my images when using a manual flash with Cowboy Studio radio triggers. One example was shot at 1/400 sec, f/2.8, 60mm, with the flash at 1/32 power. If I shoot without the remote flash or use the built-in flash, the images look normal. What causes this, and how can I prevent it?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
14
You're shooting with a shutter speed faster than your sync speed (most likely 1/200 or 1/250). Your camera's shutter consists of two curtains -- the first one opens to begin the exposure, and the second follows it -- closing to end the exposure. At speeds slower than your camera's sync speed, these two curtain movements allow at least a tiny fraction of time between opening and closing, but at faster shutter speeds, the closing curtain is actually chasing the opening curtain, creating a moving slit of exposure. A flash occurring during such an exposure is only going to illuminate part of the sensor - hence, the dark bar.
This is a bit tricky to picture, but this video shows exactly what's happening with those curtains:
Originally by user269. Source · Licensed CC BY-SA 4.0
user269
11y ago
0
Generated from our catalog & community — verify before relying on it.
The black band is usually caused by shooting faster than your camera’s flash sync speed. On most DSLRs, the maximum sync speed is around 1/200–1/250 sec. At faster shutter speeds like 1/400 sec, the shutter curtains form a moving slit across the sensor, so a normal flash burst only lights part of the frame, leaving the rest dark.
Radio triggers can make this worse because inexpensive triggers often add a small delay, so even if your camera’s rated sync speed is 1/200 or 1/250 sec, you may need to use 1/160 or slower for a clean frame. Weak batteries in the trigger can also increase timing problems.
To prevent it:
- Set shutter speed at or below your camera’s sync speed
- If needed, go slightly slower when using budget radio triggers
- Try fresh batteries in the triggers
Your exposure compensation setting won’t cause the black band; the shutter/flash timing is the real issue.
Recommended products
UniqueBot
AI11y ago
Your Answer
Related Questions
Why do I get a black band at 1/200s when using wireless flash triggers?
Why doesn’t high-speed sync work with a Canon 430EX II on a CowboyStudio trigger?
Why are my off-camera flash photos dark when using wireless triggers on a Canon T5?
Why do black rectangular blocks appear in my photo?
Why does my Yongnuo YN568EX III underexpose above 1/16 power in S1 slave mode on a Nikon D7200?