[Odarlin]

Originally Posted by Linus

... Now, someone correct me: F stop is how long the frame stays open to allow light in, no? This means that nighttime photos come in clearer?

Originally Posted by Selenay

A lower f-number denotes a greater aperture opening, which allows more light to reach the film or image sensor.

Aperture is literally just the size of the hole allowing light in.

Shutter speed is how long the image will be exposed to light.

To add to an excellent post:
When you have a lower f-stop(and wider aperture) you generally can have a shorter shutter speed because since more light is hitting the film at any given time you need less time(as stated above) and it can be super handy for no flash night picts that are not stationary or you can't use a tripod for. Add fast film and you have something formidable to play with at night.

When you do use a lower f-stop though you will have a smaller depth of field; the range surrounding the plane of critical focus in which the focus is acceptably sharp. A low f-stop is a common technique used to get those shots in which part of someone/thing is in focus and everything in front of or behind them is very unfocused.

My cameras are mostly manual 35mm SLR’s; on these there is color coding on the aperture adjustment ring that correlate the different f-stops to the distances on the focusing ring that give a general idea of what depth of fields will be available for what aperture settings. It might look very different on your cameras but it should have something. It isn’t hard to figure with a bit of play though. Maybe you know all this.

I just pulled out my cameras after not looking at them for a number of years. It is fun and inspiring to see what you are doing!