Imaging Problems and Used Digital Cameras Part One
Many people have expectations that are unrealistic when it comes to digital photography in that they believe that digital images are perfect when it comes to detail and color. The truth is that many problems can arise in the digital domain. Some of these problems are inherent while others are caused by settings on the camera that are set incorrectly. When you are buying a used digital camera you may experience imaging problems that have nothing to do with the fact that you have purchased a used camera. Take the time to understand what types of imaging problems exist so that you can narrow down the problems you are experiencing with your used digital camera.
Noise
"Noise" refers to any part of the image that wasn't there in the original image. Noise can be seen as dots or specks in the picture, as washed out white areas, or as blotchy areas where there really should be no shading.
Photographs that are traditional will have imperfections but these imperfections have come to be accepted in the photography medium. The grain of the film is considered to be a noise pattern that is brought about by film emulsion. This noise pattern is often used when the effect sought is creative. It is expected that digital photography is cleaner than using film but the fact is that noise patterns are now an important way to measure the quality of the image.
In digital photography there are a variety of different noise sources. Noise is a byproduct that occurs when light is converted into digitized numbers. Each photosite that makes up the image sensor will function by changing the photons into electrons. A random fashion causes the photons to cluster to the photosites and the electron conversion can then create artifacts that are unwanted.
When the electrical signals are amplified at each photosite, noise can often be produced. The electrical charges are very tiny and therefore need to be amplified before they reach a level that can be used. The noise that is created during this amplification process is considered to be "static", the same static that you can find in radio broadcasts but this time visual artifacts are created.
Reducing Noise
You can do several things to reduce the amount of noise. You will notice the noise the most in shots where there is an exposure time that is extended or where there are high ISO settings. An ISO setting is closed connected to the speed of the film. High speed film will take pictures using exposure times that are short. This works well for action shots such as when you are filming athletic events. In digital cameras a high ISO setting will create more noise than a low setting.
At the same time, exposure times that are long will create lots of noise. Exposure settings that are long can be used when you want to take a picture in light conditions that are low, such as inside shots. When you keep the ISO setting low, and the exposure time short, you'll minimize the amount of noise in your pictures.
Removing Noise
You can take care of the noise after you have taken the picture. Software packages are available which will remove any artifacts of noise. The software works by using "camera profiles" to eliminate and reduce the noise that some camera brands typically produce. Software for reducing noise is easy to use and is quite cheap to buy both new and used.
However, the problem with a camera profile is that it won't match exactly the noise that your own camera produces. I f you want to reduce noise as much as possible you can use the following technique:
Once you take a picture that you think might be affected by any noise you should take another picture using the same settings on your camera. This second picture needs to be completely black. This means that the shutter on the camera needs to be closed, the viewfinder needs to be covered, and the camera should be put into a bag so that no light comes into the body of the camera.
The second picture will then be used as a "noise profile". This means that it will match the noise that is in the first picture. You will use this noise profile when you're editing the picture using software, such as Photoshop, by subtracting the noise from picture number one. You will get the best results using RAW files but you can use the same technique for JPEG files.
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