Can a Nikon lenses work on a canon DSLR?

       Each manufacture has it's own unique lens mounts. Even inside of each manufacture they can have multiple lens mounts, example would be Canon has the EF and EF-S mounts which fit the majority of the EOS line of camera's however due to frame ratio's camera's like the 1d mk II can not use EF-S mount. Check your camera's mount type and use the lenses that are built for that mount only. You can purchase non manufacture lenses for typically less then the manufacture however I would suggest trying the lens on the body before buying to confirm the lens is sharp and able to work correctly work.