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I've just received and external flash : YN 560 III and I'm learning to use it.

This is a manual external flash, it was mounted on the hot shoe of my Nikon D3200.

For one picture I set the shutter speed at 1/400s and the EXTERNAL flash speed at 1/128 (is this the speed?). This resulted in an unexposed black bar at the bottom half of my image.

Can someone explain why this is happening? I understand that pop-up flashes have limitations, but I thought external flashes overcame these limitations.

Here's a sample photo:

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  • \$\begingroup\$ Pictures, or it didn't happen. ;) Also, the make/model of camera might help. I assume you don't get the black banding without flash? \$\endgroup\$
    – digijim
    Apr 22, 2016 at 17:28
  • \$\begingroup\$ Your sample photo is an excellent example of the shutter sync issue discussed in the answer this is marked as a duplicate of. \$\endgroup\$
    – mattdm
    Apr 24, 2016 at 8:44

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The issue is your shutter speed in combination with the fact that the YN-560 models are all manual-only flashes. See: Why is my camera limited to a shutter speed of 1/250th when the flash is up?

Essentially, your camera controls your shutter speed by changing the size of the gap between the two shutter curtains. At your camera body's maximum sync speed, the gap between the two curtains is still big enough to leave the whole sensor uncovered. If you use a shutter speed faster than your camera body's maximum sync speed (typically 1/200s or 1/250s), you'll get black bars at the top and/or bottom of the frame because the shutters can be covering part of the sensor when the flash burst goes off, and the flash burst is a lot faster than your shutter speed.

You can get around this limitation with high-speed sync. But the only flashes that do high-speed sync are typically ones that also do TTL--the YN-560s do neither. There are reasons not to get a manual-only cheapie as your first/only flash. (See: What features should one look for when selecting a flash?).

See also: Neil van Niekerk's tutorial on high-speed sync.

1/128 is the flash power ratio. Basically, when set to 1/128, it's firing at 1/128 of full power. Manual power settings are doubles of each other (1, 1/2, 1/4, 1/8, etc.) to be 1EV apart from each other, so you can balance out the flash power against your ISO, aperture, and shutter speed.

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  • \$\begingroup\$ A very silly question so do excuse me, but the flash manual says the speeds can range from 1/200 to 1/20000s. So if I matched both at the same speeds, why wouldn't they work? As always a great answer: @inkista Thank you very much! \$\endgroup\$
    – HelloWorld
    Apr 22, 2016 at 17:56
  • \$\begingroup\$ Won't work because above the flash sync speed, only part of the sensor is exposed at any given time (as explained above). So, the flash fires for, say, 1/4000s, and during that time only part of that sensor is exposed, by the slit between the two shutter blades, so only that part sees the image. \$\endgroup\$
    – Caleb
    Apr 22, 2016 at 18:03
  • \$\begingroup\$ On that note I must ask how does sports photographers manage? TTL flashes and high end bodies? \$\endgroup\$
    – HelloWorld
    Apr 22, 2016 at 18:08
  • \$\begingroup\$ @user2440943 Usually fast lenses and no flash, but sometimes high speed sync flash and high shutter speed or else high flash power (enough to overpower ambient light) and shutter speed <= sync speed. \$\endgroup\$
    – Caleb
    Apr 22, 2016 at 18:22

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