Getting Your Photo Correctly Exposed

When I first began taking pictures, I did not know how light affects my images. As I improved my skills during my journey as a photographer, I learned about how different parts of the camera can affect the quality of my work. The creation of a photographic image depends on the quantity and quality of light received by the camera’s sensor. This process is called the Exposure Triangle.

What is Exposure Triangle

The Exposure Triangle is comprised of aperture, shutter speed, and ISO. Your camera uses these three controls and the attached lens to control the amount of light received by the camera’s sensor. Each of the legs of the Exposure Triangle will impact the quality of light. The illustration above shows how each of the elements of the Exposure Triangle interacts with the others. Daniel Peters from Photoblog in Hamburg, Germany has a downloadable image of the Exposure Triangle that you may use when taking photos.

Elements

Aperture

The aperture on your camera is what controls the amount of light when taking a photograph. It is how wide the lens opens when you click that button. A large aperture will give you a photograph where the area of focus is small and the depth of field shallow. This is good for close-ups like portraits or close-up photographs of wildlife. The aperture setting should be from f1.2 to f5.6. Shallow depth of field will give clarity to the closest thing in your photo. (The smaller the f-number, the larger the aperture setting, and thus, the more light let in).

A small aperture, on the other hand, is necessary for landscapes and distant shots, as it will give clarity in foreground and background details. The settings for small aperture would be between f16 to f32. For mid-range shots the in-between settings of f8 to f11 will give high clarity and detail, maximizing the sharpness of your lens. A small aperture will give a greater depth of field.

Depth of field can be explained as the distance between the closest thing in your photo and the furthest thing. If you have good depth of field, the details in your photo will be clear at both five feet and fifteen feet. Most digital cameras have a great depth of field, which is why it is hard to blur the background so the foreground is sharp and in contrast. Most cameras with an automatic depth of field cannot be set manually. If you want to take photographs that are very precise, you need a camera that allows manual adjustment.

If you want clarity of detail between 1 and 2 ½ meters, then use a 22mm lens and set to f8 and a bit less than 1 ½ meters. This means that the background will be suitably unsharp, throwing the foreground into relief. The larger the aperture number, the less time is required to take a photo. So if you want to photograph something that is moving, make sure your f-number is fairly large.

Correct exposure is determined by both shutter speed and aperture, but when you are shooting during times of low light such as dusk, you will need to adjust the aperture to let in as much light as possible. In bright conditions, the aperture should be set to a smaller f-number to prevent excessive light spoiling the picture.

Many people don’t worry their heads about such things as aperture, exposure and shutter speeds and if this is you and you’re happy with your photographs, that’s great. Otherwise, a little attention to details like this could improve the quality of your photographs a great deal.

Shutter Speed

Shutter speed is one of the most important things to learn about in digital photography. It is this that controls the amount of light beaming onto your camera’s sensors. Cheaper digital cameras don’t allow you to manually adjust the shutter speed, so if you want to play around with this, get a more expensive one. Great results can be achieved by adjusting the shutter speed.

Shutter speed is measured in F-stops. It is written as f-stop or f stop, it doesn’t matter. Inside the lens of your camera is a shutter that rotates. Shutter speed is a measurement of how fast the rotation is. To get a good shot of a speeding car, you will need to have a shutter speed of something like 2000th of a second. Any fast moving photography relies on fast shutter speed; sports photographers for example, need to have a fast shutter sped to catch people who are moving fast. So when you see a shot of a footballer caught and frozen in full flight, you’ll know the photographer had his camera set to a really fast shutter speed.

Digital cameras are perfect for this type of photography. In fact, some of the newspapers have closed down their dark rooms due to the new technology. Babies, kids, and animal photos also need to have fast shutter speeds, or you risk missing the great moment that only lasts for a second. Shutter speed also depends on your lighting. Taking photographs in reduced lighting can be improved by decreasing your shutter speed.

A reflex digital camera – single lens, is the ideal one to use if you want to adjust your shutter speed. Some cameras allow you to change both exposure value and shutter speed, but not shutter speed alone. With these, you can fiddle and adjust to your heart’s content, but still, being able to adjust shutter speed alone is a great benefit. When you are just learning, go with the shutter speed first, then try out the aperture before trying both together. This will give you a good sense of what effects you can get with each alone and what shots you need to adjust both for.

ISO

ISO isn’t new to the world of cameras. If you can remember back to the day of film you could purchase 100, 200, 400, 800 ISO film. Today, on your digital camera you can change the ISO with just the press of a button. So what is ISO?

The ISO speed is a measure of your camera sensor’s light sensitivity. The lower the number the less sensitive while the higher the number the more sensitive. If you were to take a photo of a subject using 100 ISO and then take a photo of your subject using 800 ISO or higher, you would discover:

  • The photo with the lower ISO speed (slower) will force your camera to use a slower shutter speed when you take the photo. On the other hand, the photo that is taken with the faster ISO speed will have a much faster shutter speed. If you are using a faster ISO you’ll be able to freeze that moment in time. If you have poor lighting, choose a slower ISO.
  • The slower ISO speed photo has less noise than the photo taken with a faster ISO. We should mention that DSLR’s perform better than the point and shoot cameras do. Therefore, you might find yourself in a situation where you have to trade off between usability and quality when lighting is poor.
  • You should use the minimum ISO speed to achieve adequate shutter speed. This is usually 1/focal length for most pictures. There might be a few stops where you will need to slow the image stabilization or make it faster such as with action shots. Keep in mind it is better to have a couple of pixels that are discolored is a lot better than all encompassing defocus or blurred images. Some digital cameras are able to pick an ISO, which is quite handy functionality.

Unless you have an understanding of how ISO works, you will have trouble making the right choice for the conditions you are taking photos under. Your ISO is as important as understanding your flash and in many ways it is more important.

The higher the ISO the larger you will be able to print our photo, but remember the higher the ISO the grainier the photo is going to be. Choose the appropriate ISO to get the clearest pictures. With digital cameras, a lot of things have gotten easier and the ISO is one of them. Now you too can be a photographer.

Camera Exposure Modes

Automatic

The Automatic Exposure mode is a setting the camera automatically selects aperture, shutter speed and ISO based on the amount of light detected by the meter. When this mode is used, the camera is operating as point and shoot.

Program

The Program Exposure mode is a modification of the Automatic Exposure mode. The camera chooses the shutter speed and aperture based on the amount of light detected by the meter. The other settings such as White Balance and ISO may be modified.

Aperture Priority

The Aperture Priority Exposure mode is a setting where you set the desired aperture, and the camera sets the shutter speed. When this mode is used, you only have to consider the depth of field needed for your shot. This setting is frequently used for still photos such as landscape and portrait.

Aperture Priority is selected by using the A or Av on the mode selector dial.

ISO should be set prior to using Aperture Priority, as the sensitivity of the sensor to light must be set in order for metering to function correctly.

Shutter Priority

The Shutter Priority Exposure is a setting where you set the desired shutter speed and the camera sets the aperture. When this mode is used, you can either stop the motion or create a blurred effect of an object in motion. This setting is frequently used for photographing sports ,wildlife and creating blurred effects in landscapes.

Shutter Speed Priority is selected by using the S or Tv on the mode selector dial.

ISO should be set prior to using Shutter Speed Priority, as the sensitivity of the sensor to light must be set in order for metering to function correctly.

Auto ISO

Auto ISO is a setting that allows you to set a range of values for sensor sensitivity based on shutter speed.

Manual

The Manual Exposure mode allows you to control all of the camera settings. When this mode is used, both aperture and shutter speed may be set. The viewfinder will display be a metering display that will change as aperture and shutter speed are changed. It will display a range from underexposed to overexposed

Manual Exposure mode is selected by using the M on the mode selector dial.

Auto ISO is frequently used with Manual Exposure.

How do we put the parts of the Exposure Triangle into use? If we adjust one of them by a full stop of light then one of the others must be increased as well by a full stop of light. An example of this is that if the aperture goes from 5.6 to 8, then the shutter speed must go from 1/125 seconds to 1/250 seconds. If you have photographs that are underexposed then it is at least one stop of light below where it should be.

Full Stops of light are illustrated below

ISO10020040080016003200640012800
Shutter Speed1/20001/10001/5001/2501/1251/601/301/15
Aperturef/22f/16f/11f/8f/5.6f/4f/2.8f/2
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