Why Is My Flash Photo Too Dark at a Distance?

Likely causes

• Subject beyond the flash's effective range at the current settings. every guide number has a real maximum useful distance at a given aperture and ISO — beyond that, the flash simply can't provide enough light.
• Aperture too narrow for the flash's power at that distance. a narrow aperture chosen for depth of field can leave a distant flash subject underexposed even at full flash power.
• ISO too low for a flash shot at range. raising ISO extends a flash's effective useful distance for a given power output.

The fix

1. Check the flash's effective range at your current aperture and ISO before assuming full power will reach a distant subject.
2. Widen the aperture or raise the ISO to extend the flash's effective reach.
3. If the subject is genuinely too far for the flash, rely on ambient light and exposure settings instead for that specific shot.