Photography 101 : The Practical Basic of Aperture And Speed


This article is targeted to photographers who wants to learn what aperture and speed can give related to its setting. The two main basic setup of taking photograph is setting your aperture and speed. In the old days, these are the only two variables that you need to set in the camera with regards to exposure. The other variable setting is ISO which is basically already determined by the specification mentioned in the film box. You just need to set that ISO number in your camera and leave it until you finish the film. You only change that ISO seting when you change to different ISO film.

In digital camera ISO can be set on the fly. You can change from ISO 100 to 3200 in a flick of a button. However ISO setting does not give any photographic effect like you have with setting the aperture and speed. ISO only determines the sensitivity of the sensor, which usually gives you ‘side-effect’ like noise in your final image. In my opinion, ISO is only ‘side tool’ to achieve desirable speed and aperture setting combination. For instance, you raise the ISO setting higher to achieve higher speed or smaller aperture. Aperture and speed are the main setting you need to achieve the effect you want to record in the sensor.

1. Aperture
Aperture determines how much light can go into your film or sensor given a certain shutter speed duration, controlled by how large the lens diaphragm opens. The effect of the selection of aperture mainly is depth of field (distance in front and behind the focused subject that is considered sharp). However the depth of field (DOF) effect also depends on the focal length and focus distance. There is one more factor which is the film format you use. The larger the format (recording area) will give you shallower DOF given the same aperture number.

Shallow DOF
Means that you have plenty of relatively blurred image immediately infront and behind of your focused subject. It is achieved by selecting lower aperture number (large diaphragm opening, e.g. f1.4 – 5.6) as well as shorten the distance between the camera and the focused subject. Usually a decent camera is equipped with a DOF preview lever that you can have an idea the DOF would be like. These days, just take a shot and review the result on the LCD to see whether you get what you want. This shallow DOF is usually preferred for portrait photography, whereby you can make the subject of your picture really stands out. Smooth rendering caused by this blurred surroundings also make nice background especially if you can choose background that has color and light intensity matched with your subject.

Deep DOF
Means that almost or entire picture element within your frame is sharp. This can be achieved by selecting higher aperture number (smaller diaphragm opening e.g. f8 – 22). Usually used in landscape as well as travel photography when you need all of the subject you take to appear sharp in your picture. Macro photography also uses small aperture opening to achieve reasonably deep DOF. Since in macro photography the subject is so close to the lens causes thinner DOF. Small diaphragm opening (higher aperture number) can increase DOF. However it is not advisable to use very small diaphragm opening. Beyond a point diffraction can cause the image to be less sharp.

2. Speed
Speed determines the duration of the film or sensor being exposed to light coming through the lens diaphragm. The effect depends on your subject movement. If your subject is static, no difference will appear on the final image. However when your subject is moving a lot, for instance like a dancer, kids running around, helicopter’s rotor, water flow in the river, etc., your speed will matter. Choosing the right speed is crucial to communicate the message you want to deliver to your viewer.

High speed (1/300 – 1/500) usually is used and considered fast enough to freeze any movement of your subject. Sport and dance photography usually requires such speed which can deliver frozen movement. However, you may want to experiment with lower speed and see the effect on the image.

Normal speed (1/30 – 1/250) is used for everyday’s photography. The selection of the particular speed setting solely depends on the available light you have at that particular moment. In bright sunny day you will need higher speed and vise versa. Travel photography, taking your children’s birthday party outdoor are good examples of using normal speed.

Very low speed (1/8 – 4 sec) is usually used for blurring the effect of flowing matter. Water flowing in the river, waterfall, waves on the shore are favourite subjects of many photographers using this technique. Water flow taken using this technique can appear like a very smooth silk. You will have to have a steady tripod to use this technique since guaranteed that you will not be able to handhold still for that long period of time. In most cases the lighting condition does not allow you to go as low as you want to achieve this effect, eventhough you have chosen very small aperture. In this case a neutral density filter is required. This filter reduce the amount of light coming into your lens without shifting any color.

Extremely low speed (up to hours) is used for photographing star trail in the night. This very long exposure also means that you need tripod to support your equipment. You also need a very good and fully charged battery if your camera depends on them to open the shutter that long.

Flash Sync Speed is the highest speed you can use when you use regular flash. This can be varied from one to other camera. This sync speed depends on where the shutter is located in the system. If it is in the camera body (curtain type) it can be as high as 1/500, but the normal sync speed is usually 1/250 or 1/125. Older camera body usually has 1/60 sync speed. If the shutter is in the lens (leaf shutter) the sync speed can go as high as the highest speed the lens can be set.

Choose your aperture-speed setting carefully, and you will have the effect you want. Understanding the effect of the combination is very important to enable you making photographs you want them to be.

Other Articles:

Buying Pocket Digital Camera for Non Photographer

Flash Tips


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