I could be wrong, but I don't think this flash is compatible with the Canon DSLRs. The DSLRs need either an E-TTL dedicated flash, or a non-dedicated auto (like Sunpak 383). One dedicated for TTL use with Canon film SLRs will not work properly.

P.S. If it hasn't cooked the Rebel Ti, it's voltage will be safe on the DRebel XT.