You’ve probably heard from other photographers that the combination of the right aperture size and the right shutter speed makes for a nice image exposure. But what is exposure?
Simply put, an exposure is the amount of light that hits either the sensor (for digital cameras) or the film (for film cameras). The more light you allow to hit the sensor (depending on aperture opening and shutter speed length), the brighter the image is going to turn out. And vice versa, the less light you allow to the sensor, the dimmer the picture gets. Depending on your desired effect, you can overexpose (let more light to simmer in the picture) or underexpose (let less light in).
For full manual cameras, you have the capability to adjust the aperture size and the shutter speed to get a correct exposure, wherein the image appears as it would see it with your naked eye, or over or underexpose your shot.
For point & shoot or consumer digital camera, you have preset exposures to suit the current lighting condition. You have presets for specific lighting conditions: sunny, cloudy, incandescent light, flourescent light, and shade, to name a few.
You also have the option to use aperture and shutter priority exposure. With aperture priority exposure, you manually set the lens opening size and the camera will do the shutter speed adjustment. With shutter priority, you set the shutter speed and the camera adjusts the opening.
Usually, in the case of presets and priority settings, the camera measures the images to match what’s seen by the naked eye. Professional photographers would refer to this as 0 (zero) exposure value. +1 would mean you’re overexposing the image, while -1 means you’re underexposing it.
Again, I will reiterate that although the general idea of a correct exposure is when you capture an image that exactly matches what you see outside the lens, you make your image what it is. It can be overexposed or underexposed to some people, but so long as it is the desired effect you want to capture, don’t let anybody tell you that you’re using the wrong settings.
