[poider (Peter)]

The more I research scopes the more confusing it becomes.
What are the differences between a 150mm reflector with a 750mm tube and a 150mm reflector with a 1500mm tube, I know that the main difference will be the f/number, how much does it affect the magnification abilities of each scope and the imaging, observing abilities, is one better for observing and the other photography?
what would be the better all round scope a 150mm smith cassegrain or a 150mm newtonian reflector????