So far I am loving the GX8, but I do miss the built-in flash for those rare times I use flash. So I remembered when I got my EP5 I played around with my SB800 on it. It was too big for that camera but the “A” setting worked great. I set the flash for the ISO I wanted and it gave me the f stop and range of use. Set my camera in manual and set the flash sync shutter speed I want (normal or fill) and then the f stop that the SB800 shows and my images are perfect (of course you can use either the exposure comp on the flash of change f stop on the camera for more or less exposure also). Mainly I use it for macro work now and it should work fine even with adapted lenses. So if you're still a Nikon shooter or still have a SB800 laying around it fits the GX8 as to size (still a big flash but ok on the Gx8) and the images are perfectly exposed.