When changing a lens, dust or foreign objects make their way into the Canon DLSR camera CMOS sensor and Sony mirrorless camera CMOS sensor through the bayonet area. Dust may also slowly make their way through other areas of the camera such as the battery compartment, SD/CF card socket areas, HDMI, Mic, USB port areas, around the viewfinder area, and some parts of the top cover area of the camera body.
From experience, when we blow air through a mirror box area of the camera or on the sensor, we can feel that air coming out of the battery compartment, SD or CF card socket area and the input/out ports. That means that if air can get through, so can tiny foreign objects like dust particles, sand and water.
A question we always get asked is how often a digital camera should be cleaned. The answer is that it really depends on the state of the CMOS sensor of that DLSR or mirrorless camera. Some customers may have had their camera for years and the CMOS sensor is pretty clean and does not really require to be cleaned. Whereas, we get some customers that get their sensor dirty within 1 or 2 months because of how they use and store their camera. Another good indicator to know when to get your sensor cleaned is when those tiny dots start to appear in your images. If you’re a avid or professional photographer, to continually maintain the quality of your photos, you may need to invest in getting your sensor cleaned a little more often to avoid any disappointments.
It’s simply impossible to keep dust or dirt particles from making their way into your sensor but there are ways of minimizing it so the CMOS sensor doesn’t get dirty ever so quickly.
Two Tips on how to keep your CMOS sensor clean:
Keeping your camera gear in a clean environment is key, ensuring the case the camera is kept in is clean.
Refrain from frequently changing camera lenses. I tend to never separate the lens from the camera body, unless I need to change to a different lens. Once I finish using my Sony A7 mirrorless camera, I keep the lens attached to the camera body and put the camera away.
Keep your lens caps, body caps, rear mount lens caps clean.