Sunday, September 14, 2008
The day I took this night picture I started a journey into sensor defects. Even if I reduced the image size you can clearly see red and blue spots in it. This spots turn out to be 'hot photosites' and are defective areas of the sensor were leakage current heat the sensor and burn the electronic film.
You can see in the posted image that my sensor has three types of defects, the red spots, the blue spots and the white dots. Some are bigger than others and they all increase with ISO sensitivity and time exposure. The ugly thing of my sensor is that even at ISO100 and 1/2 second I have clear defects.
What camera do you have dear reader? can you make me a favor? take a black picture with your camera, just leave the cover on and use this settings: ISO400, 30 seconds, jpg format at max resolution, no contrast or sharpening increase. Send the picture to abracaarbres(flower)gmail.com and indicate the model of your camera and the ambient temperature when you took the image. Temperature is quite inportant, in the case of my camera the defects I get using ISO1600 at 5C look similar to the defects of ISO100 at 30C
Here a list of sensor defects
Here an interesting page on sensor noise that a good friend has forwarded me