On our side of the pond we pronounce Canon the same way as "cannon". Neither the american nor english pronunciations of nikon are correct, in japanese the "I" is prounced as an "ee" sound.
Alright, here we go with linguistics again
The Japanese pronounciation of the term Canon (yeah, it's pretty funny to watch Canon-sponsored programs/commercials and hear the different pronounciations for the same name) is more like "Kyah-non" where the "non" sounds like the french "non".
However, the catch phrase/slogan used in the commercials seems to be unified under the English pronounciation.
All these from a company named after the Bodhisattva of Mercy (Kannon)....