Flash Firing Restriction Due to Temperature Increase

Repeated use of continuous flash or modeling flash at short intervals may increase the temperature of the flash head, battery, and areas near the battery compartment.

Repeated flash firing gradually increases the firing interval, up to approx. 4 sec., to avoid wearing out or damaging the flash head from overheating. Continuing to fire in this state will automatically restrict flash firing.

Note that when flash firing is restricted, a temperature increase warning icon is displayed, and the flash photography firing interval is automatically set to approx. 10 or 45 sec. (levels 1 and 2, respectively).

Temperature Increase Warning

At each of the two levels, a different warning icon is displayed as the internal temperature rises. Continuing to fire after level 1 is reached changes the state to level 2.

Display / Beeping Level 1
(Firing Interval: Approx. 10 sec.)
Level 2
(Firing Interval: Approx. 45 sec.)
Icon Temperature increase (flash firing restriction) level 1 Temperature increase (flash firing restriction) level 2
LCD panel illumination Lit Blinking

Continuous Flash Count and Rest Time

The following table shows the estimated continuous flash count until level 1 warning display, along with the estimated rest time required until normal flash photography can be resumed.

Function Estimated Continuous Flash Count
Until Level 1 Warning
Estimated Rest Time Required
Flash Coverage
14 mm*1, 24 mm28 mm 35 mm 50 mm105 mm
Continuous, at full output () 32 times or more 47 times or more 55 times or more At least 35 min.
Modeling flash ()

As measured in manual flash mode according to Canon testing standards.

Uses new AA/LR6 alkaline batteries

1: When using the wide panel


  • Do not touch the flash head, battery, or near the battery compartment after continuous flash firing.

    After repeated use of continuous flash or modeling flash at short intervals, do not touch the flash head, battery, or near the battery compartment. The flash head, battery, and area near the battery compartment may become hot, which poses a risk of burns.


  • Do not open or close the battery compartment cover while flash firing is restricted. This will cancel the flash firing restriction, which is potentially very dangerous.
  • The firing interval becomes longer as the flash head becomes hotter, even if no level 1 warning is displayed.
  • After a level 1 warning appears, stop using the Speedlite for at least 35 min.
  • Even if you stop firing after a level 1 warning appears, a level 2 warning may still be displayed.
  • Flash photography in ETTL flash mode or in high temperatures may restrict the flash count sooner than indicated in the table.
  • For flash count precautions, see Continuous Flash Firing and Modeling Flash.
  • In rare cases, environmental factors such as temperature increase may prevent firing.
  • No warning is given by LCD panel illumination when C.Fn-22 is set to [1] (), even if the flash head becomes hot.