Al,
This is the compatability chart
http://www.sigma-imaging-uk.com/flas...-compat.htm#03
I have found a review against Canons top unit so worth a look
http://photonotes.org/reviews/sigma-ef-500-super/
I need to see if I can find a downloadable manual as from other comments I have read.
1) Poor manual with some of the English sections written in French. Manual does not properly explain the functions.
2) After a 8 flash firing the unit has to be turned off for 10 mins to cool down.
I will get back later.
Don