http://www.nikonchat.com/nikon-fm3/

How can I use a Vivitar 285HV flash?
I have a Nikon FM3, a flash Vivitar nd I can not remember what the color wheel on the side? I I know how to configure it on my camera body, but not the settings.
I'm not familiar with the exact model, but appears to be a variable flash output. Turn the dial around until ISO (like ASA) lines in a window or some kind of indicator. Then, there will (usually) a red and blue marker. There would be switch or other device to select the output of the flash which is also a color code. Set the flash to one of the colors. Search on line for the color. The brand will align with an f-stop number. Set the camera to that number. Go for it.
Nikon FM3A.mov