Back in time when I bought my K10 I also bought the Sigma EF-500 DG Super flash and it has been working without any problems since...even with my K-5 which I bought about 4 years ago....Recently I bought the K-3 Prestige Edition which have the firmware 1,11......which made me think that most problems from the original K-3 has been solved by now.....but, hell no.....to my disappointment there seems to still be a "huge" delay when I use the flash, internal or external, there is a delay/lag between the moment I press the button and the moment the effectively take the photo....felt very annoying when I used the flash for the first time......AND, I also have a problem when using the external flash not always "working".....a problem that never excisted while using the flash on my K10 and K-5.. I have noticed that sometimes I simply have to "restart" either the flash or the camera after each shoot taken with the flash....then I have a working flash for each single picture. Anyone who have experienced this too.....and have done what ????