This is page 2 of 4. "Flash" begins here.
People pictures are a prime example of an exception. The photo of this little lady shows what I mean. Often, when you are shooting outside, the background will be super bright while your subject will be darker.
In a program mode, without flash, the camera will set itself to a happy medium between the bright background and your shaded subject. This almost always results in both of them being improperly exposed. The right lighting unit/s will balance this out so you end up with a nice picture.
The above picture was taken without what's known as "filler-flash." The next, is with. The term "filler flash" simply means that your camera mounted unit is the secondary source of light.
In these pictures the sun is the main source of light. The camera unit is secondary; therefore the camera unit is "filler." It fills the dark shadows caused by the primary source of light. In this example, the primary source being the sun.
In the top picture I shot her in aperture priority. In order to correctly expose her I would have had to do it in manual mode.
Yet, if I had correctly exposed her in the first picture the resultant, severely overexposed background would detract the eyes of the viewer from the actual subject. Using filler light, both the foreground and the background are well exposed.
When your subject is in direct sunlight there will be harsh shadows on their face. When your subject is in the shade, almost invariably there is enough bright sunlight in the background to cause a substantial difference between the proper lighting for your subject and that for the background.
The end result is that during the daytime, outdoor filler is often necessary. I use filler when I am shooting people outside. Most other subjects normally seem to be fine without.
Remember, all lighting units have a very limited distance. And that effective distance is even shorter when you are shooting in bright sunlight.
I use manual mode when I am shooting with artificial lighting. Every camera, that I know of, automatically sets the shutter speed to 1/60th of a second when the artificial lighting is turned on. That's bad because people move.
I find at 1/60th many of my subjects blur if it's not a posed shot. And even when people are posing they tend to move at the most inconvenient of times.
I cannot find any way to increase the shutter speed in any of the program modes; even in my high end camera. Well, shooting in manual mode allows me to set the shutter to a speed I like.
I find that 1/250th or thereabouts works well. Even when restless children are in the picture I can capture it crisply.
One thing to note; when in manual mode, with the shutter speed set to 1/250, one does not have to reset the aperture. You can still use an aperture of f8.
The reason being, the camera's microprocessor will set the flash output accordingly. Even when the camera's exposure indicator bar shows the picture will be underexposed; in the daylight it won't be.
There are limitations to this. The flash unit has a limited amount of power. When you are far from your subject, anything beyond the maximum range will be under exposed.
The next limitation is; if you want the background properly exposed you will have to use an aperture setting much closer to, but not necessarily exactly, what your camera meter shows as correct. This comes into effect when shooting in low light situations. In order to get the results you want, you'll have to experiment in each situation.
Another limitation to using 1/250 and f8 indiscriminately is that many cameras have a maximum shutter speed they allow when the flash is on. If you are in the bright sunlight, without flash, your shutter speed is far in excess of 1/250. If you turn on the flash and your camera automatically sets the shutter speed to 1/60th, you may not be able to override it.
For example, my high end consumer DSLR camera will not allow a shutter speed of greater than 1/250th when the flash is on; even in manual mode. So, outdoors, in manual mode I have to use a faster film speed than I would like and/or a narrower aperture [which results in a greater depth of field] in order to maintain a correct exposure as I use the filler flash.
In that case you can change your film speed and/or aperture or you simply use your camera in full program mode. Your camera will make all the necessary adjustments for a properly exposed shot.
Please reread and practice the information in the following note. it is very important.