So, I’ve set myself a pretty easy task. Put all of photography into four easy steps. No sweat.
The most important part of a picture is the subject. You could have the best equipment and knowledge but a picture is only as good as what’s in it.
Clearly, I can’t suggest ideas for subjects in your photo, but perhaps I can suggest how you frame it. One of the most well-known techniques is called the Rule of Thirds. This basically makes your subject more pleasing to the human eye by splitting the photo into thirds, either vertically or horizontally. The idea is that the subject of your photo is placed in either one of the thirds or on vertices. This makes it aesthetically pleasing to look at.
Aperture refers to the size of the opening which light travels through to get to the camera’s sensor. Essentially, it refers to how much light is let into the sensor. If the lighting condition is constant, and the shutter speed adjusts for the amount of light being let in, then changing the aperture will increase or decrease the depth of field (amount of the photo in focus). It’s important to note that increasing the Aperture number (F1.5 to F12) actually decreases the diameter of the aperture.
Different photos have different apertures. For example a portrait will have a relatively low aperture number so that the subject is in focus but the background has a soft blur. In contrast to this, a landscape will use a high aperture number so that the maximum amount of the picture is in focus.
The shutter speed and aperture have to work in unison to stop the photo being over or under exposed (too bright or dim), compromising each time the shutter is clicked. So if you’re taking a picture in circumstances where there’s not enough light, the compromise will be that the aperture number will be lower, in order to maximise the shutter speed.
ISO is the sensitivity of the sensor in a camera. In your average DSLR (the big cameras most pros and some amateurs use), the range will be from about 100 to 6400. This will be drastically higher in more expensive models. The iPhone 6, in comparison, has a range of ISO 32 to 1600. The higher the ISO number, the higher the sensitivity of the sensor. This has the advantage of lowering the shutter speed, however it also means your photo will be more grainy.
So in low light , you’ll want the minimise the shutter time to have the sharpest picture possible. To achieve this, you might want to consider raising the ISO number. In contrast to this, you’ll want to have the lowest possible ISO number when light is not an issue, for example using a tripod.
The shutter speed is fairly easy to understand. It’s the time between when the shutter opens (to expose the sensor to light) and when it closes. Under identical circumstances (same ISO, aperture and lighting) the faster the shutter speed, the more of the picture is in focus.
The general rule is that to get a sufficiently sharp picture, you should always have a shutter speed of 1/60th of a second. As a result of this, in low light I would recommend that you change your aperture or ISO settings first, so that the shutter speed is unaffected.
Sometimes, you may be shooting in circumstances where shutter speed is not an issue. For example using a tripod. In this case you should change shutter speed last, so that ISO and aperture are not unnecessarily affected. However this is only valid if the subject of your photo remains still or is intentionally moving. An example would be taking a picture of a landscape at night or body of water to get a smooth effect.
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Photo credits: Flickr (creative commons) commons.