there is always more than one definition, but my definition was correct because it was based on usage in the sentence.So you agree there is more than one definition.i gave the #1 example:
1: existing on or coming from the outside <extraneous light>
2a : not forming an essential or vital part <extraneousornamentation>b : having no relevance <an extraneous digression>
3: being a number obtained in solving an equation that is not a solution of the equation <extraneous roots>
http://www.merriam-webster.com/dictionary/extraneous
unfortunately the english language is really weak like that, so it's easy to misunderstand.
my view is, your argument about focal length affecting vibration intensity is not wrong.What are we talking about? The impact on an image. Do you form an image without a lens? If not, then how is the lens "outside" of the system making the image?
what it does is totally detract from the real issue at hand here.