Cleaning your sensor

At the heart of your camera is the CMOS sensor, where images that have passed through your lens are converted from analog light to digital information. Arguably the most sensitive and critical component of your camera, if a digital sensor is damaged, your camera’s operation and value are seriously compromised.

In front of your CMOS sensor is a thin layer of transparent material called a low-pass filter. Technically, this is where dust actually sits when it appears to be on your CMOS, and it is the filter that you clean. Incidentally, this is why dust spots in your images look slightly shadowed — they are not actually directly in contact with the sensor, but sitting very slightly above them. If your camera has the sensor self-cleaning mechanism, it uses what is called a piezoelectric element to literally shake the filter and CMOS using an electrical charge, effectively loosening dust particles so that they fall away.

Because this part of your dSLR gets exposed to dust when you use it normally, such as by changing lenses, this is where dust often accumulates. Additionally, over time, your camera can even generate dust internally as components get older.

Internally, cameras are constructed of exceptionally dust-resistant materials. However, dust still has a way of getting stuck where you don’t want it. In many newer cameras, Canon has taken steps to help prevent and deal with dust on your CMOS with a self-cleaning sensor mechanism and an automated dust-delete software that maps dust spots for later identification and removal in the Canon Digital Photo Professional software. While innovative, Canon has received some criticism that the self-cleaning sensor is gimmicky and not very effective, and that the dust-delete software doesn’t work well and it must be used with Canon’s software program; it won’t work with other image-editing applications such as Photoshop, Lightroom, or ACDSee Pro. I’ve tried it myself with mixed results; it seems that it can work on larger spots, but the smaller ones don’t always disappear (although they do sometimes move around a little).

For cameras that do not feature self-cleaning sensors, and for self-cleaning sensors that get stubborn dust particles that won’t go away, you’ll need to take matters into your own hands. Cleaning a sensor can be a very daunting prospect to many photographers, so if you’re not having any luck with the simple dust removal method described next, you may want to consider taking a camera with a dirty CMOS to a professional camera store or repair center for cleaning. Or, if you’re a little braver, you may want to try the advanced sensor-cleaning options I cover next:


Turn off your camera when changing lenses and CF cards. If your power is still on, generated static electricity can act like a dust magnet.

Category: Camera care

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