Quote Originally Posted by JimD View Post
Thanks for the link.

They come in 300w, 400w, 500w etc etc ....... roughly how many watts (I know they're not the same of course) does a speedlight put out? What I'm asking is how much brighter is say a 300w strobe compared to a Canon 580EXII speedlight?

Hope that makes sense.
From what I gathered, a speedlite (580EX/SB900) puts out about 60W depending on the model. Some can go as high as 120-150W but these are mainly specialised models.