noob question on f numbers on zoom lens

[avatar12m]

am i right in thinking a 2.8-5.6 lens is no better at max zoom than a 4.5-5.6, so no real point in buying one if i'm usually taking photos at max zoom ?

i just bought a nikon d5100 with a 70-300 4.5-5.6 and just wanted better auto focus / brighter pictures and was wondering best way to go without shelling loads of money out on a prime lens as i'm on a tight budget.

 

[hyperst]

What post processing are you doing?

A lot can be done with such things as Lightroom

 

[Raymond Lin]

In terms of aperture they are no different if both at say 300mm are both at 5.6. However how the lens is made can cause quality difference in terms of sharpness, bokeh and focus speed etc.