Operation Manual

48
The batteries are exhausted.
Install new batteries. (→ page 10)
Batteries are installed incorrectly.
Install the batteries in the proper orientation. (→ page 10)
The 420EX's mounting foot is not securely mounted on the camera's hot
shoe.
Slide the mounting foot all the way into the hot shoe. (→ page 12)
The camera's hot shoe contacts or the 420EX's contacts are dirty.
Clean the contacts.
The 420EX has not been used for 90 sec.
Press the shutter button halfway.
Press the test firing button. (→ page 15)
The locking collar has not been loosened enough.
Loosen the locking collar until the locking pin disengages. (→ page 12)
If flash is used in the < > mode under low-light conditions, a slow sync
speed is set automatically. A blurred picture is prone to occur if the
camera is handheld at a slow sync speed.
Use a tripod. (→ page 22, 36)
Set the camera to the < > mode. (→ page 18, 32)
With high-speed sync, the Guide No. changes depending on the sync
speed. The faster the sync speed, the shorter the effective flash range will
become.
Check the Guide No. before taking the picture. (→ page 50)
The slave unit's wireless selector is set to < >.
Set the wireless selector to < >. (→ page 13)
The slave unit is not within the master unit's wireless transmission range.
Position the slave unit within the master unit's wireless transmission
range.
The slave unit's wireless sensor does not face the master unit.
Point the slave unit's wireless sensor toward the master unit. (→ page
44)
The master unit's flash mode is set to < > or < >.
Set the master unit's flash mode to < >. (→ page 43)
The flash does not
fire.
The 420EX cannot be
detached from the camera.
The subject looks
blurred in the
picture.
With high-speed sync,
the picture came out
underexposed.
The slave unit does
not fire.
Troubleshooting Guide
The power turns off
automatically.
K133 (E) 02.4.1 3:05 PM Page 48