Mic placement: Off-axis and On-axis

[TheBones]

i hear the terms on axis and off axis all the time and i think i know what we're talking about here, but is there any good resource online that might be able to show a diagram or paint a clear picture? explainations only usually leave me asking the same questions. thanks for your time.

 

[IK Obi]

Imagine the mic to be a flash light. Move it around until you get a clear picture of what your trying to record.

 

[arcadeko]

Youtube "mic placement"

 

[mixsit]

http://www.audixusa.com/docs/specs_pdf/OM5.pdf

http://www.audixusa.com/docs/specs_pdf/CX112B.pdf
Here's some examples of axis responses.
I don't know if Audix is just being more detailed here or if they actually happen to be more directional but they show narrower in the top than some other similar brand's plots.
If you look at the same for a guitar speaker (couldn't find one) you'd likely also see rather very narrow response in the highs –big drivers (relative to frequency) beams the highs.
A fig-8 ribbon with long/narrow element placed vertically, presumably would have wider top p/u in the horizontal than in the vertical.