From Digital Camera World, an explanation as to why the P program mode is a much better alternative to the fully auto mode
In this guide to your camera’s Program Mode – or P Mode – we’ll answer many of the common questions about what it is and how it works, as well as show you how to get more creative results by shifting the aperture and shutter speed.
Program Shift, also known as Flexible Program, is an advanced semi-automatic exposure mode – although you won’t find it listed as an option on your camera’s mode dial.
What you will find is the letter P, which stands for Program mode. Select this, and the camera will adjust both the aperture and the shutter speed to produce what it judges to be the best exposure for the scene or subject you’re photographing.
However, you can manually override the camera’s choice, ‘shifting’ to a different combination of aperture and shutter speed. It’s by doing this that you effectively enter Program Shift mode.
It sounds a bit automated – so why wouldn’t I just use my camera’s Automatic mode?
Program Shift is what’s known as a semi-automatic mode: you can let the camera handle the whole picture-taking process, or you can roll your sleeves up and make some adjustments manually.
For example, you can select an ISO sensitivity, tweak the white balance and picture style, and dial in exposure compensation. Your camera’s Automatic mode – the green icon on the mode dial – doesn’t give you this level of freedom.
You may be able to choose a drive setting and decide whether to fire the flash or not, but that’s about your lot.
Are there any drawbacks of using Program Shift?
If you know you want a particular effect, such as a shallow depth of field or a slow shutter speed, it can often be quicker to work in the appropriate mode mentioned above.
Having to scroll through a range of combinations in Program Shift until you come to the one that best matches the effect you’re looking for takes a little longer.
On some cameras, any ‘shifted’ exposure combination in Program Shift will only be available while the camera’s meter is active.
If you take your finger off the shutter release and the aperture and shutter speed disappear from the viewfinder or the LCD screen, the shifted exposure will be lost.
When you dab the shutter release to activate the meter again you’ll be back in Program mode, with the initial combination of aperture and shutter speed that’s been suggested by the camera. See the full article here