Great question for sure and as already said there is no real one answer here as all tho telescopes only gather light and focus it to a point for viewing and magnifying by the eyepiece so we can see a magnified object and on this its a common wrong idea that telescope's/ eyepieces magnify a distant object , they don't , they actually bring an object to the angular size it would look when much closer .
For example looking at say Jupiter at 200x is not seeing the planet 200x bigger
but it is what Jupiter would look like if it was 200x closer than it physically is so instead of an average distance of 440 million km's at 200x it would look like it was only 2.2 million km away if using the naked eye , that's 1x .
All telescopes do this in their respective design peramiters to acheave the image .
Another mis-conception is that a long fl will show a dimmer image to a short fl telescope of the same size ,, wrong
, for example a 4 inch refractor at f15 would be exactly as bright on all objects as a 4 inch f6 , 4 inches of light gathering is 4 inches of light gathering , law's of physics cant be broken .
But with the awesome quality of todays multi and anti-reflection coatings there is difference to be seen as the older f15 scopes had nothing or at best a single coating of MgFl on the outside but that's another story
.
Brian.