Sigma Em-140 Macro Flash help needed
Has anyone here got a Sigma EM-140 ? I recently bought one to use on a Pentax K-5 with Tamron 90mm lens. I'm having a few difficulties getting exposure correct. I though TTL would be a lot easier than this. All my test shots are over exposed by quite a margin.
I set the camera to P mode (although I've also tried Av mode) and noticed that the lens set a flash sync speed of 160th sec. The manual for the Pentax says the flash sync speed is 180th sec. I don't know if this mismatch is a problem of if there is a work around apart from me manually underexposing by 1/3 stop to compensate for the exposure. I still get a large percentage of shots over exposed even when I reduce the flash power on the EM-140.
I used a ring flash set up years ago with a Canon set up and don't recall it being this tricky, the E-TTL exposure there was more or less spot on. This is very frustrating as I like the K-5 and would like to get this sorted. Unfortunately the manual for the Sigma flash wasn't that comprehensive. I wondered if I was doing anything wrong ? I set the flash unit to TTL and expected the flash to tell the camera how much to expose the test shots at F11. I found that unless I really stopped down to say F32 that the test shots were over exposed.
Any helpful suggestions welcomed. I'm new to this so it's quite possible I've missed something.