The technical side of photography is not difficult to grasp; anyone who wants to learn can do so. For a basic understanding of the cameras use in photography there are only four key areas that you must understand to move forward. These are ISO, shutter speed, aperture and lighting.
The first 3 are associated with your camera and the last is what we use to create a photograph with; i.e. light. They are all interrelated and one depends on the other. Once you have these concepts under control, you are ready to explore the next stages in your photography.
With these four areas, it does not matter whether you are using film or digital, the concepts remain the same. Digital cameras are the same as film cameras; the media is the only difference.
In addition, when you understand these concepts, you can take your camera setting off automatic and switch to manual. This will give you the absolute control you want and need to produce more dramatic photographs.
Part 1 ISO
ISO is an acronym for International Standards Organization. It was previously known as ASA, or American Standards Association. It applies to both digital and film cameras.
If you set your camera on automatic, the camera may select the ISO for a given situation, and provide you with a less than satisfactory image.
Getting your exposure correct is vital to making better looking photographs. The solution is to get the shutter speed, aperture and ISO settings working together smoothly. Once you have this under control and start working in manual, you will not want to give back control to the camera. Having said that, there may be times where you want to give control back to the camera. An example is for fast moving events, where you don't have the time to set the camera manually for each shot.
The aperture and shutter speed alone are not responsible for how your photograph is achieved. Light sensitivity of the digital sensor or film is also considered. Both digital and film cameras have a setting which allows you to adjust the ISO. ISO is a measure of how sensitive the recording medium - film or sensor - will be to light. The higher the ISO number, the more sensitive it will be to light. Conversely, the lower the ISO number, the less sensitive the sensor, and more light is needed to render your photograph.
The problem at high ISO settings, where only a small amount of light is required by film or sensor, is that a level of noise or grain is introduced into the image. For film the effect is called grain, and gives the appearance of dots which make up the picture. For digital sensors, it is called noise and it can give the appearance of noise on a TV screen that has little or no reception. While film grain has been used to great visual effect by many photographers, the noise recorded by high ISO settings in digital cameras is a disconcerting effect of the medium.
The ISO is indicated by a set of numbers, which for most film and digital cameras, double with each increment in the setting. The camera normally has 100, 200, 400, 800 and 1600. Some film cameras go well beyond this to as low as 6 ISO and as high as 6400 ISO. These numbers designate that with each increment or decrement, half or double the amount of light is needed to achieve the same exposure. This is also true of shutter and aperture, so you can see how they all work together. Change one function, and it is necessary to change another to achieve the same exposure.
For example, if you wish to have a long shutter speed to blur the effect of water in a waterfall, you need to slow down the shutter speed. This means you need to compensate for the additional light by stopping down the aperture to correct the exposure. The effect of stopping down the aperture also has its ramifications; it will give greater depth of field. This may or may not be desirable in this example. It is something that you must consider though.
The next installment (Part 2 Shutter) is directly related to ISO.
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