Hello all,

When I try to use second curtain sync on a 5D Mark III using my YongNuo YN560-II speedlite, by accessing the Flash Function submenu of the External Speedlite Control menu, I get the error "This menu cannot be displayed. Incompatible flash or flash's power is turned off." (it's on). According to the 5D3 manual, this is the only place where you can set this value, so I am fairly stumped as to how I go about this. I really wanted to use it for long sparkler exposures on the fourth. Still do!

Searching the internets, I get plenty of answers, from it's only available on TTL-capable flashes to Canon disabling access to this menu to any third party speedlites.

Can someone enlighten me as to how I access this feature? Something as simple as firing the flash at the end of the exposure should not be so difficult. Thanks in advance!

Martin