>>3352829Nikon has always had a voltage regulator in their bodies, I use old Vivitars on my D800 all the time, even the non HV 285 is fine on this.
Sony cameras on the other hand don't, found that out by killing the hotshoe on an a6000 with a VIvitar 285HV.
>>3352826it might be missing an external battery pack, is it a potato masher style flash? what's the brand / model, or more pics of the flash