First I hate flashes, I am not used to them. I have a 544 sunpak and shooting with a Pentax 67 Where I thought the settings on the camera must be set on X but what is the F stop supposed to be on? There is a dot right next to 2.8 so I set my F stop on that. My negatives where highly overexposed. This was a test trial. I shot ten images ranging from intensity of the flash. can I close down my fstop to say f 11 and get better results?