The trouble with digital SLRs is that dirt can get on the sensor, if you look at a picture you have taken you may see small grey blurry spots on the lighter parts of your image, such as skies. The marks will be grey and fuzzy because the dust is not actually in contact with the surface of the sensor but in fact the dust is on the surface of the low pass filter which lies on top of the sensor. The gap between the sensor and the dust is enough to throw the spots out of focus and allow some light to creep underneath.
You can test to see just how much dust you have if any, by either taking a picture of a white wall or a plain piece of white paper using a telephoto lens or a lens zoomed out to its longest focal length. Select the Aperture priority mode (AV) and set it to the smallest aperture (f22), you do not need to get the image sharp as this does not effect the test so a tripod is not necessary if the shutter speed is very slow. Take the shot and transfer the image onto your computer and with either Photoshop or any other good image software magnify the image to 100%. The chances are that you will see some grey spots, but you have to decide if they will spoil your photos. If you feel that your sensor does need cleaning then I would advise you to look at the cameras instruction manual on how to do this or go to the manufactures website, the process is normally quite straight forward.
Now the reason I actually wrote this article is to help you prevent dust actually getting onto the sensor, so here are a few tips:
1. If your are going to change the lens, firstly switch of the camera as this reduces static on the sensor and therefore reduces the risk of attracting dust, then swap your lenses over.
2. Try to avoid changing your lenses in a dusty environment, I know this isn’t always possible, so if you have to change the lens point your camera down with the lens mount facing the ground, this stops dust falling into the opening.
3. If you do not have a lens on the camera never leave the mount open and exposed, always have the body cap on it.
4. Keep the body cap free from dust. Did you know that the body cap and lens cap attach to each other? This will keep the inside of both caps clean when a lens is on the camera.
I hope this article has helped you? Do you have any other tips to stop the dust getting on your cameras sensor?
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