Infrared Panel

[tmccall]

I dropped my Canon Speedlite 420ex and broke the Inrared Panel on the front.  The unit appears to be functioning properly, however as an amateur I probably wouldn't know the difference.  I can acquire the part from Canon for $12 plus shipping.  Does anybody here know how the absence of the Infrared Panel might affect my flash, or the photos I take, if I use it before I get the new part in?