[kevgermany]

All you ned to know about f stops:

It's a way of getting identical lighting from one lens to the next without even more complicated maths.

Gaps between the stops are set to match the exposure increments on the shutter speed. It's more obvious on shutter speeds, but the relationship of one stop to the next is to multiply or divide the amount of light by two. So it's obvious that going from a shutter speed of 1/30th sec to 1/60th sec halves the amount of light, but going from f4 to f5.6 also halves the amount of light...

Smaller numbers let in more light cos the f stop is the ratio of the aperture size to the lens' focal length and is more correctly stated as f/8 - i.e the aperture is 1/8th of the focal length. This is why faster lenses are fatter than their slower counterparts of the same focal length.

Smaller stops (higher numbers) give more depth of field because you're approaching a pinhole camera design, where light coming in through a very small aperture is always in focus, irrespective of distance.

It's worth learning the main values and getting a feel (by using them) for the depth of field they give. Depth of field varies with lens focal length AND image/sensor size - it's not an exact science, just approximations.

1.0 1.4 2.0 2.8 4.0 5.6 8 11 16 22 32 are the standard whole stop values.
Note the sequence - each one is double the one two positions before.
You can see that f32, the last I've quoted, is double 16, with 22 sitting between. Makes learning them much easier.

Lens aperture rings generally click from one stop to the next. On older cameras that's it, although many will work in between the click stops. Newer lenses generally have click stops at each half stop interval for finer tuning. The DIN exposure scale had 1/3rd stop increments, which is where the 1/3rd stop settings on modern cameras come from - probably overkill now, but was useful (sometimes) for slide film.