Refractor "light-gathering" question

Do two refractors of the same fL/Diam. ratio have the same light gathering ability in terms of imaging?

I'm trying to learn here, not start an argument.

Thanks.

Light gathering in terms of point sources (stars, for example) will be the same. For extended objects, the f# is just like on a camera - the lower the number, the faster you can record the object - a 4-inch f/6 will record and extended object 4x faster than will a 4-inch f/12 (but the f/12 will have a larger image scale - the object will, at the image plane, occupy 4x more area in the f/12 system). I suppose this is another way of saying that a 4-inch gathers as much light as another 4-inch.

What you call fL/Diam. ratio is called the F ratio or focal ratio, as in F 10 or F 4.5.

Light gathering ability is dependent on aperture alone. (Diameter of the primary).

However, as another A-marter has described, on extended objects, a faster (lower number) F ratio will expose a given piece of film or ccd sensor quicker.

Alex