For a given shot, there can be multiple combinations of aperture and shutter speed which will provide a “correct exposure”, that is an exposure which is neither over nor under exposed. Choosing which combination is an important step in a great digital photography portrait.
If you are working with a seamless background without design elements (no swirls or “blobs”) then you won’t have to worry so much about blurring the background. In this case, the apertures surrounding f/8 seem to provide a clear picture of the subject without bringing too much of the background into focus. Set the aperture to f/8 and then set the shutter speed to around 1/125 sec. If you are shooting children or pets, who are more likely to move, then try a faster shutter speed. Take a test shot and evaluate your settings. Pay particular attention to the background (is it too focused) and the hair (is it in focus the whole way back). Adjust your settings and re-examine the test shot until you have it just right.
Remember that with a fully manual setting, it is necessary to adjust both the shutter speed and the aperture each time you make an adjustment to either. Many cameras will help with this need by “suggesting” the corresponding setting once you have chosen the other setting to the one that matches. However, if you are just going to use this combination then you are probably better off using the semi-manual modes instead.
Next Up: Check Out Part 4 Below: General Camera Settings for Portraits for Semi-Pro Photo Shoots.