Photography Question

[carpenterdean]

Hi guys, i'm fairly new to digital slr photography so my question is, when setting the aperture on the camera in manual mode do i need to stick to the parameters of the f rating on the lens aswell, for instance the lens i have is 18-55mm with an f rating of 3.5 - 5.6 but i can set the aperture greater or lower than this in manual mode do you have to stick within the lens capabilities?
Cheers rick.