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.
|Autumn by valenttin|
from Harvest Festivals
|Cardinal, Male by paul katinas|
from A Big Year - birds
|.. by Amar Vignesh|
from Unintentional Blur
|Freeze Time by WhistlerOne|
|Sir Mick Jagger by HetFotoAtelier|
from - Concerts : When The Lights Come On -