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Dave,
I don't think anyone is wrong, just looking at the it from different angles.
We all agree FOCAL RATIO = FOCAL LENGTH / APERTURE
For instance Stan Moores article states that f-ratio has little impact on image depth when APERTURE is kept constant. On that basis his article is sound. I would even add that as focal ratio is increased stellar limiting magnitude is improved since the sky background appears darker.
However, if you keep FOCAL LENGTH constant then varying focal ratio has a big effect as you are varying aperture. This is how photographers tend to think - i.e what focal length do I need to frame my subject. Of course in astrophotography we often find ourselves not having enough focal length.
Sorry, if I am getting over pedantic...
Terry
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