Originally Posted by
Donald
Liz
We run the risk here of getting our 'highers' and 'lowers' mixed up. I think it's better to use the terms 'wider' and 'narrower' when we talk about apertures. Wider means f2, f2.8, f4 etc. Narrower means f16, f22 etc. The wider the aperture the more light is let in. Also, the wider the aperture the shallower the depth-of-field.
So, if we go back to the 70-200 f4: At f5.6 there is half as much light let in as there is at f4. And then there is half of that (one-quarter of what you get at f4) let in at f8, and so on. Each aperture stop either halves or doubles the amount of light you let in, depending on which way your turning the control. But remember your full stops are 1.4 2.0 2.8 4 5.6 8 11 16 22. The other numbers you might see on your camera are third or half stops (depending on how the camera is set up).
So, for the sort of stuff I do, I do tend to operate at f8, f11, f16. That is not to say I don't go wider or narrower. It all depends on what I'm trying to create. But generally, that's the sort of region I work in. But I don't go for fast shutter speeds. If you are into wildlife, for example, you may need very fast shutter speeds and you may also want a shallow depth of field. So, you're more likely to be needing to operate at wider than f4.
Is that making any sense?