I use manual mode generally and a tripod. So, I 1st start with a ISO100, F16+ and meter against what my main focal object will be a in photo and adjust speed until meter reads 0. It totally depends on the situation but if you use AV mode the camera will decide for you.
For hand-holding, I generally have ISO400 and start at f8 and adjust speed from there depending what my trusty in-camera meter tells me. Here is a sampler hand-held. As you can see I ended up at f6.3 and 1/13s with satisfactory results.
In the case of below I exposed against midpoint in the building where it was lightest.
Code:
Make Canon Model Canon EOS 50D
Aperture Value f/6.3 Exposure Bias Value 0 EV
Exposure Program Manual Flash No Flash
Focal Length 14 mm ISO 400
Metering Mode Spot Shutter Speed Value 1/13 sec
In this example, I exposed on the floor as it was grey tone.
Code:
Make Canon Model Canon EOS 50D
Aperture Value f/6.3 Exposure Bias Value 0 EV
Exposure Program Manual Flash No Flash
Focal Length 10 mm ISO 400
Metering Mode Spot Shutter Speed Value 1/2 sec
Both are terrible examples to show you because technically I should have been using a tripod at such low exposure speeds however they worked out for personal consumption.
Allen...