There seems to be a continued... and baffling, misconception on the Internet and often in journalistic media, on the usage of the words CANNON and CANON.
According to the Oxford Dictionary:
1. a large, heavy piece of artillery, typically mounted on wheels, formerly used in warfare
2. Billiards & Snooker, chiefly British a stroke in which the cue ball strikes two balls successively.
3. Engineering a heavy cylinder or hollow drum that is able to rotate independently on a shaft.
1. collide with something forcefully or at an angle: the couple behind almost cannoned into us; his shot cannoned off the crossbar
2. Billiards & Snooker make a cannon shot.
Origin: late Middle English: from French canon, from Italian cannone 'large tube', from canna 'cane, reed'
1. a general law, rule, principle, or criterion by which something is judged: the appointment violated the canons of fair play and equal opportunity
2. a Church decree or law: a set of ecclesiastical canons [mass noun]: legislation which enables the Church of England General Synod to provide by canon for women to be ordained
3. a collection or list of sacred books accepted as genuine: the biblical canon
a. the works of a particular author or artist that are recognized as genuine: the Shakespeare canon
b. the list of works considered to be permanently established as being of the highest quality: Hopkins was firmly established in the canon of English poetry
4. (also canon of the Mass) (in the Roman Catholic Church) the part of the Mass containing the words of consecration.
5. Music a piece in which the same melody is begun in different parts successively, so that the imitations overlap: the very simple rhythmic structure of this double canon [mass noun]: two quartets sing in close canon throughout
Origin: Old English: from Latin, from Greek kanōn 'rule', reinforced in Middle English by Old French canon
Can we agree that one shoots things at you, and one is a rule/principle/criterion? Is it really that hard?
Oh dear God, I forgot it is also a camera brand....