Let’s assume you follow my advice and use your flash, as fill flash, outdoors. Say for pictures like this.
In that case the question will be, what mode do you use on your camera? You want aperture in a certain range to ensure sufficient, but not too much, depth of field, and you want the shutter in a range that ensure sufficient stability but that is limited at the upper end by the flash sync speed (normally around 1/200th second).
- Program mode: this will work, but you get no control over either aperture or shutter speed. Not the preferred mode unless you are in a hurry.
- Manual mode: you meter for the background and set your camera accordingly. Flash lights up the foreground. This is practical when you know aperture and shutter speed and their effects well, and when the light does not vary too much.
- Aperture mode: good for determining the depth of field. But there is a drawback. Outdoors, if you open the aperture, your shutter speed could easily exceed your flash sync speed. Result, an overexposed picture. Or if you stop down the aperture, the shutter speed could get so slow you get blurry images.
- Shutter speed mode: if it is bright, you can set your shutter speed to just below your sync speed, say 1/200th second. The camera will now choose whatever aperture suits this. The risks are fairly low – worst case, you get a wider or narrower aperture than you wanted. If it is dark and your ISO is low, you can get an underexposed image.
- “Aperture and shutter priority”: on some cameras you can select “Manual exposure, plus auto ISO”, which effectively means “aperture and shutter priority”. If you set your aperture and shutter wisely, the ISO will be in an acceptable range. The danger is that you need lower than available ISO (overexposed picture results) or that you need high ISO (noise, or “grain”, results).
As you can see here, there are certain strategies, but there is not one perfect one that is easy to use at all times. That is why photography has a technical aspect you need to learn.
A different approach: Rather than worry about modes too much, look at what they do. You need to look through your viewfinder and be aware of shutter speed, aperture, and ISO. Look out for:
- Shutter too slow: blur
- Shutter too fast: flash sync speed will be exceeded, and overexposure results
- Aperture fully open: overexposure will occur, and depth of field will be narrow
- Aperture too closed: too much will be sharp
- ISO at its lowest: overexposure may result
- ISO too high: noise (“grain”) will result.
Then adjust whatever you like to get all three variables into the right range.
For the shot above, I used shutter speed priority with my shutter speed set to 1/200th second. I chose an ISO of 200 to get into an acceptable aperture range (I was aiming for f/5.6).