Good morning, I am having some trouble trying to catch a specific image. I want to capture a shot of my kids waving a sparkler around AND have the flash fire at the end of the long exposure to catch the child holding the sparkler (with the light path from the sparkler visable). I have no problems setting the shutter speed for the shot but cannot find where/ how to set the flash to fire. I currently have a Nex 5N with flash attached. Any assistance would be greatly appreciated. Thank you.