My 550D recognizes, however, unfortunately a little contact on the right side of the hot shoe if an external flash is connected. The camera then switches off the internal flash selbiger can in the settings then can not be turned on.
The trick: carefully cut about one third of the right rubber track with a sharp knife, then the contact is no longer pressed deep enough and the camera will flash again.
Other disadvantages: For me, the "level" of the gum dissolves. Sticking helps however. Accurate measurement results should not expect ...
In addition, the part can be very easily removed from the hot shoe (already in front prune the rubber rail) ...
Basically, however, the product is OK, so 4 stars.