Anyone who takes many photographs will eventually hear the words “aperture” and “f-stop”. These are terms that refer to the exact same thing on the camera – the aperture is the opening in the lens that allows a controlled amount of light to strike the sensor and it also creates the depth of field in the image.
The depth of field in any photograph is the area of the picture which is in sharp focus, and anyone interested in macro photography (very deep zoom imagery) is going to always have to consider the depth of field and the f-stop.
Let’s first look at how f-stop settings affect a traditional photograph. If we use a lower f-stop, such as f/2.8 we are actually opening up the aperture to its largest degree. This means that the subject will be in sharp focus, but the foreground and background will be blurred. If we do the reverse, however, and shut the aperture down to f/22, we are flattening the image and making the overall scene generally focused instead.
So, when considering the f-stop of a macro photographic subject, we must consider the depth of field, which is actually almost non-existent. If the photographer wants the entire subject in good focus, this means they will want to use a higher f-stop number, such as f/16 or more.
This, however, does create the need for a slower shutter speed to let in enough light for the exposure. Unfortunately, lighting for macro photography can be incredibly challenging, and this is because any on-board flash units, or even shoe mounted flashes, are unable to light the subject. This is due to the fact that there is not enough distance between the camera and the subject, and the flash will actually shoot over the subject without lighting it at all.
The solution used by most macro photographers is to set their f-stop at a higher number, set the shutter speed to a slower speed than normal, and mount the camera on a tripod. Most photographers will also use their timer to prevent the triggering of the shutter from shaking the camera and ruining the image, or use a remote trigger to prevent the camera from being shaken in any way.
Generally this results in a great macro photographic image, but if the lighting is still a problem there are some solutions available. The most popular is a special macro photography lens that has two small lighting units built into it. This allows the subject to receive direct lighting while not affecting the settings on the camera. Alternately, many photographers use their traditional, on-board, flash units but place reflectors above and behind the subject. This floods the scene with light, but can also require some experimentation and test shots to get the best and most controlled results.