Can the external overhead flash used by Canon be used on Nikon cameras?

as long as it is the flash of the hot shoe interface, it is universal. However, due to different contacts and different TTL methods, if different brands of flash are mixed, they can only use the exposure value that manually adjusts the flash.

In addition, synchronization will be limited. For example, if the SB6,8,9 supporting FP high-speed synchronization is installed on PENTAX or Canon machine, it will not be able to use high-speed synchronization, and only the flash synchronization speed of the machine will prevail.

Both p>NC flash devices are standard hot boots, and there is no need for any transfer. In fact, even if there is transfer, the correct TTL information cannot be obtained because of different physical definitions. Nikon is iTTL and Canon. If you need to transfer, Minolta /SONY is the only one in Japan, because their hot boots are different from other homes, so you have to transfer them, or you can't install them.