How does a sensor get dirty?
Contaminants can enter your digital SLR camera in various forms and in many different ways, but they all affect the quality of your photographs. Some contaminants come from internal man made sources within the camera such as chamber lubricant and manufacturing dust that become shaken out, and others from external sources in the environment such as pollen, small fibers from clothing, dew and organic dust.
How does this affect my photographs?
When contaminants are present on the low pass filter that sits in between the sensor and mirror, the sensor pixels are blocked from receiving that portion of the image and show up as artifacts or dark spots and lines on your photographs. Depending on the size of the debris, these artifacts can be barely noticeable or can potentially ruin your image.
How do I keep my sensor clean?
Every time you change your lens you are exposing your sensor to external contaminants. Because your sensor is an electronically controlled component of the camera, it becomes magnetically charged during normal operation. This magnetic charge literally draws both internal and external debris onto the sensor and filter surface and holds it there until it is manually removed. Many times the debris becomes chemically bonded onto the sensor or filter surface.
Always use a lens mount cap when the lens is removed to prevent dust from entering the camera. It is recommended that you change your camera lens indoors. However, there are many times when you need to change your lens outside. Make sure you change your lens quickly and protect the camera as much as possible from dust and other contaminants.
Refer to your camera’s manual for recommended techniques on changing lenses.
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