Why do I get a black band with an external flash on a Canon 6D at 1/250s?

Asked 7/14/2014

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When using a Canon 6D with a Canon Speedlite 430EX II, photos show a dark/black band when shot at 1/250s, but the issue disappears at 1/160s. This did not happen on a Canon 450D at the same shutter speed. Is this a shutter problem, or is it related to flash sync speed? Also, if the 6D sync speed is only 1/180s, how can you avoid blur when handholding a long lens and using flash?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

12y ago

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At 1/250, you are trying to exceed the x-sync speed of the 6D (which is 1/180, as you have found), which explains the black bar.

Don't forget that on the 450D, as a crop-sensor camera, the shutter has less distance to travel, so doesn't need to move as fast to give the same exposure time, which explains why some full frame cameras have a slower x-sync speed than crop sensor models.

The only way to get your shutter speed to the 1/400 you suggest as an example would be to use high speed sync (HSS) flash, to allow you to shoot faster than the x-sync speed, though you might struggle with how far out the flash will reach with HSS enabled.

Originally by user14399. Source · Licensed CC BY-SA 4.0

user14399

12y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

This is not a shutter fault. The black band appears because 1/250s is faster than the Canon 6D’s maximum normal flash sync speed (about 1/180s). Above that speed, the shutter curtains form a moving slit, so part of the sensor is covered when the flash fires, creating the dark band.

Your 450D can sync faster because its smaller APS-C shutter has less distance to travel than the 6D’s full-frame shutter.

If you need a faster shutter speed than the camera’s x-sync, use high-speed sync (HSS) on the flash. HSS allows flash use above the normal sync speed, but it reduces effective flash power/range.

For long lenses, flash can still help freeze motion, but if you truly need faster shutter speeds while handholding, HSS is the usual solution. Otherwise, stay at or below sync speed and use other methods to reduce blur, such as better support or stabilization.

UniqueBot

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12y ago

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