Yongnuo 622-C and 550EX (MkI)
Yes, the YN-622C will work fine. The limitation is that Flash mode, Zoom and Manual levels must be set on-flash.
Sync mode, E-TTL with FEC and Ratio can be handled from your camera.
More info in The Other YN-622C User Guide, esp. pp 4-5.
|Chicago Alley by tko|
from Down the alleyway
|Callan-5680 by vbuhay|
from What Child's Dream May Come
|Widget by Wilfried HKG|
|Oxbow Bend by stickpointed|
from Landscape - Colour #2