All cameras, both digital and analog film, combine three essential elements - ISO, Apeture (f/stop), and Shutter Speed to transform light into an image. Learning the role of each of these functions and the way they interact is essential for any aspiring image maker.
ISO -
this controls the “light rating”. In classic film, this is the canister number that allowed the chemicals on the film to be more or less receptive to light. In digital cameras, it sets the camera to be more or less receptive to light. Choosing your ISO is your first step in ensuring proper light receptivity. The lower the ISO, the less receptive your film or sensor is to light, the higher the ISO, the more receptive your film or sensor is.
Examples of appropriate ISO based on setting:
ISO200 - full daylight, strong sun, very bright
ISO400 - perfect middle ground, suitable for most shots. Clear inside lighting, overcast outdoor lighting.
ISO800 - sunset, lowlight
ISO1600 - dark, moody lighting, dispersed lighting.
Aperture(F/stop)
This is the size of the hole in the lens that light can enter through.
The BIGGER the number, the SMALLER the hole.
For example, a camera set to f/5.6 will be wide open, and is ideal for photos where the focus of the image (the subject) is far away or large (think group photos, landscape photos).
For a more intimate portraite photo, you may choose to close your aperature to say f/12, creating a blurring effect in the background and bringing the focus more deliberately on your subject.
Most cameras range from F2.16-F16, so F16 is almost closed, F2.16 is all the way open. F4.5 is a standard setting that will suit most of your needs.
note:a smaller aperature will impact your light metering as the amount of light capable of entering your camera will be forced through a smaller hole. This will likely require an adjustment in shutter speed and/or ISO.
Shutter speed
This is how quickly the camera eye will open and close when the trigger is pressed. To adjust the shutter speed, turn the wheel above the camera shutter trigger. Shutter speed is your easiest control shot-to-shot once your ISO is set for the scene.
To ensure your light is optimal before taking the shot, hold down the shutter trigger half way and watch the light meter within the viewfinder to appear. For digital cameras: when turning the shutter speed dial, a small green digital tick mark will move along the light meter at the bottom of your viewfinder. When the green tick mark is centered, you can be sure you have properly light metered for the shot.
Note: any lower than 1/50 will usually pick up shake and make for a foggy or blurry picture. However, extending the shutter release can create a sense of motion that lends itself to a myriad of dynamic and thematic approaches.
Zoom
To adjust the zoom, turn the large wheel closest to the camera body. Looking down at the camera, you will see numbers from 18mm-55mm. This is the range of space you have with this lens.
Focus - To adjust the focus on the lens
- When in auto focus, holding down the shutter trigger half-way will pull the shot into focus.
- If you want more precise control, switch the notch on the side of the lens from AF (auto focus) to MF (manual focus) and turn the small outer wheel on the lens to adjust the focus.
Underexposure vs. Overexposure
Exposure refers to the amount of light the film or sensor is exposed to. Too much light can create a “blown out” image, or one that is overly bright and may lack detail. Similarly, an underexposed image may be grainy, dark, and lack detail. While there is certainly a range of exposure that lends itself to the best images with the clearest details, many image-makers adjust higher or lower on the spectrum to imbue their images with a deeper sense of emotional meaning. Darker, slightly underexposed images can create a sense of mystery, of moodiness, of quietude and contemplation. Lighter, slightly overexposed images can create a sense of playfulness, dreaminess, and evoke nostalgia. Exposure is determined by combining ISO (the film or sensors light sensitivity), apeture (how much light is entering your camera) and shutter speed (how quickly the camera is “blinking”). These three functions work in tandem to produce optimal exposure.
The image on the left shows under exposure, which is darker, and details are lost in the grass and the midground. The lightmeter bar on the bottom shows that the setting is two marks below optimal exposure. Digitally altering underexposed images is slightly easier because more “data” (also called “information” or “details”) are embedded in the image.
The center image is the correct exposure. The details across the photo are clear and crisp and the lightest part and darkest part of the image are visible. The light meter indicates that the exposure is centered. This photo will be the easiest to edit as all of the data is clear.
The right image shows over exposure - or letting in too much light. The details of the sky and grass are almost completely lost. The light meter indicates that the exposure is set two notches too high, and is above optimal exposure. When you overexpose a photo, the light “deletes” the data within the photo, and editing this photo will not bring the details of the clouds back into the image.