Friday night I met Ken at Gallup Park. After meeting with him last week and getting some pictures taken, I was looking forward to it again. I do enjoy shooting with someone else.
The smaller the f-stop, the larger the aperture. That is, with a f-stop of f/2.8, the opening of the lens is wide open. If I were to go to f/32, the other end of the scale for this particular lens, the aperture becomes very small. My depth of field would increase so that pretty much everything would be in focus. Assuming I had focused the lens on my subject.
Conversely, if I decrease the f-stop by one step, the aperture
increases. This will allow twice the amount of light to pass through in
the same amount of time. If I want the same amount of light to pass
through, the shutter will remain open for less time.
If you increase the f-stop by one step, the aperture decreases by one step. The amount of light passing through the shutter in a given time period is half what it would be with the larger aperture. This means that the shutter speed doubles. It will go from, say 1/125 of a second to 1/250 of a second.
On the other hand, if I decrease the f-stop by one step, the aperture increases by one step. The amount of light going through the shutter in a given period doubles so the shutter speed will halve. If your original shutter speed was 1/125 of a second, it will go to 1/60 of a second.
This may seem overwhelming, but once you figure it out, you can start doing the math in your head and today's more advanced cameras often have settings that let you easily allow them to keep the shutter open for a longer or shorter period of time than it would in automatic mode.
Here you can see how the small f-stop led to a very shallow depth of field. I was hoping to get the whole cluster in focus without bringing too much of the background into focus.