focal ratio redux

I thought I was beginning to get a handle on the focal ratio issue and then I read this "myth"/misconception from the Televue site:
Myth #3: Faster telescopes show brighter images.
This is a misconception carried over from photographic use, where the fast f/ratios do mean brighter images and shorter exposures for extended objects. Telescopes with equal apertures and equal magnifications have the same visual image brightness, regardless of the objective's f/number.

"Myth #4: Long-focal-ratio telescopes give higher-contrast images.
In general, refractors offer the potential for higher contrast because mirror coatings, by their nature, tend to scatter more light. But when comparing well-made, highly corrected refractors, there is no gain in contrast with instruments of long focal ratio.

Reflectors too, if well made and having the same size of secondary obstruction, will have the same contrast at the same magnification regardless of the f/ratio. "
http://televue.com/engine/page.asp?ID=141

Now I am again confused. It seems to be saying I can get a good fast apo/ed and get as good results (contrast-wise) as a slower focal ratio apo/ed telescope. I want a good 100mm-115mm refractor so as long as the optics are good, and my primary goal is planetary observations, this seems to say f ratio is irrelevant. Has that been a common experience? Is the ratio only important for astrophotography? Is "contrast" not the same as seeing sharp details? Is this website wrong? Sorry if I am beating a dead horse... But I need to buy a telescope based on specs and without prior firsthand experience.

Jackie Pritchard said:

... But I need to buy a telescope based on specs and without prior firsthand experience.

Jackie,
Do you buy a car without a test drive?
Buy a house without seeing the inside?
Marry without going on a date(s) first?

While Im here, can I borrow $10,000? It doesnt matter that you dont me and I dont know you, I'll pay you back, "promise".

1. See you local astronomy club for firsthand scope experience and free advice. Please dont be one of those people that shun astronomy clubs.
2. Read your "Starware" and "Backyard Astronomer's Guide" available at library and bookstores
3. Speak to one of the helpful people at Anacortes Telescope
& Wild Bird www.buytelescopes.com
4. A longer focal length will give higher magnifications than a shorter focal length. Look to achieve a high enough magnification for planetary study while using longer focal length eyepieces.

4" (100mm) f/6 refractor with 20mm ep =
[COLOR="Blue"](scope fl = 600mm / ep fl= 20mm) = 30x[/COLOR]

4" (100mm) f/12 refractor with 20mm ep =
[COLOR="Red"]1200 / 20 = 60x[/COLOR]

The focal ratio will help in dtermining the exit pupil with any given eyepiece. Generally useful exit pupils are between 5mm and 1mm. An f/12 scope with a 6mm ep gives a 0.5mm exit pupil, too small for some people. A f/6 scope with a 6mm ep gives a 1mm exit pupil.

An f/5 dob with a 40mm ep gives a 8mm exit pupil, too large for most applications, as the secondary abstruction will be visible, especially in ligh-polluted skies.

Its easier to get high magnifications with a longer scope, without resorting to barlow lenses and extremely short fl eyepieces. Hope this helps. Look into a Televue 102
John

John and Jon, thanks for the advice and explanations. It sounds like focal ratio is more important for achros and perhaps less for very well made apos/eds. I live where seeing conditions are not great (Pacific Northwest) so I am looking to go 4" refractor.