Originally posted by ChrisFe When the flash is connected to my K5 either by PC socket or a simple ISO to Sony adapter in the hotshoe the flash does not work everytime I release the shutter.
This should not happen when you use the PC socket, unless the flash is also connected to the hot-shoe.
How many pins does the hot-shoe connector have?
If there is more than one pin then perhaps the flash is erroneously telling the camera that it isn't ready to fire yet.
It may also be that the adapter somehow creates this undesired behaviour.
If the flash won't fire even though you don't have anything else but the PC sync cable connected to the camera, I can only imagine there is perhaps something funny going on, such as a negative trigger strobe voltage that confuses the camera.