Good question. I have a peltier cooled ccd (atik 460) and the fan stays on during the entire exposure, but it doesn't affect the final picture at all, touching

Good question. I have a peltier cooled ccd (atik 460) and the fan stays on during the entire exposure, but it doesn't affect the final picture at all, touching the camera I can't feel any vibration, but can hear the fan. Quality is much better than in my fanless Canon 400D.