Yes folks, another long and possibly boring but also rather useful excerpt from my Photography Notebook. I have heard a few people talking and asking about sensor cleaning, and figured I would share my notes with you all. Don't be scared. Just read over the steps and follow along. It's super easy. You can do it!
Sensor Cleaning - Our camera sensor is the worst place to get dust on because it will show up terribly on our images (especially in bright skies or using high f/stops). The sensor is also the most fragile part of our camera, so blasting it with canned air or just wiping it down with a sock is a very bad idea. There are some great methods of cleaning the sensor, but first we will test for dust.
Testing the Sensor - Sometimes sensor dust shows up on our photos and sometimes it doesn't. Here is an easy way to test our sensor.
- Find a solid bright area to take a test exposure. Use a blank white wall, pure bright blue sky, or the best would be to just make a pure white file in Photoshop, press the “F” key until it is in full screen, and use the back-lit monitor as the target. This works very well.
- Aim the camera at the target and zoom in so that only the blank bright area is in the frame (around 50mm is good). Using aperture priority mode, set the aperture to f/22 or higher. Switch to manual focus and make sure the focus is as far off as possible (infinity).
- Now we’ll take an exposure. Don’t worry if it takes a few seconds, we can even slowly wave the camera around at the target. Camera shake is fine here case because we are only testing the sensor here, and not the focus.
- Lastly, open the image in Photoshop and look for dark blurry spots. Zoom in and play with the curves and contrast of the image to see what might show up in the frame. What works well is using (image>auto-color) to get a good view of the dust. If it has some nasty spots, then it is time to clean.