A couple of years ago I was processing some photos and noticed something really strange. A few different images all had the same kind of mark on them in exactly the same spot. I immediately thought that the problem was the lens (I used the same lens for all three photos), but there were no marks or spots on the lens. That’s when I began to think that it had to be the sensor.

After doing a little research I found a couple of websites that had the same kind of test you can do to check to see if the camera sensor is dirty. Below is one way you can do it:

You should shoot something plain like a clear blue sky or a white wall inside your house or apartment. You can also use your PC screen as substituted in the instructions following.

1) Create a new image in Photoshop or any other application (a blank Word document viewed in full screen mode is fine). Fill the image/document with white (or any other light color will do). Be sure to view it in full screen.

2) Set the camera to the following:
a) Mode – Aperture Priority
b) Setting – Aperture to minimum f/22 – f/45
c) Lens – Manual Focus set to closest focus setting
d) Features – Turn off all special functions like sharpening

3) Zoom in until only the white image/document is visible through the viewfinder or live view screen on the back of your camera.

4) Take three pictures of the image/document on the computer screen. Depending how bright your monitor is, your exposure may be a couple of seconds for each photo. During the exposures, move your camera back and fourth being careful not to point the lens outside the area of your white image/document. Moving the camera during the exposures insures that you are not taking pictures of dirt on your monitor. This should be done within a matter of an inch or two from your monitor.

5) Take the images into Photoshop or any other image editing application.

6) Inspect the images. If all three images have the same spots in the exact same area, that’s where the dust spots are.

If you have to clean your sensor, be sure to check the instruction manual for your camera. Usually it will give you info on how to handle cleaning the sensor. Most of the time you can try locking the camera mirror up (with the lens off the camera) and using a blower to clean particles off the sensor. If you’re looking for a good air blower, check out the one I use by clicking here.