Tuesday, August 08, 2006
Sensor cleaning - the before picture
My 20D's sensor was really really dirty. About 14 months of use with only occasional blasts of air from my rocket blaster (and before that, one of those wimpy little air blowers). Boy was it UGLY! These 3 images were taken by using the kit lens at 55mm focal length at with the camera set to f/36 in Av mode at ISO 100 so that the exposure is several seconds. Using a white sheet of paper with the lens focused at infinity, I then shot the paper from close range and moved the camera to blur any remaining detail in my "flat field". At f/36, the dust on the glass in front of the sensor is quite sharp and easy to see, made even better by stretching the contrast for display here. You can see just how effective the rocket blaster is - it did remove some of the big loose stuff, but a lot of the dirt on my sensor is really pretty firmly stuck to the glass window and the wet copper hill sensor cleaning method is quite necessary.