Canon film cameras metered off the film in real time. The shutter would open and expose the film, the flash would fire and the metering would cut the flash when enough light was output. When a film-era flash is used on digital it fires, but never gets the command to end the flash burst and winds up firing at full power.
WIth flashes like the EZ series a workaround is to put ND gels over the flash to cut output, but its not very practical.
So despite his best intentions Dad gave you paperweight.
