I have just had to take my cannon into get the sensor cleaned. Are there any tips that people can give me to minimize the risk of keeping dust / crap out of the camera. The guy at the store said that due to the zoom action on the lens it can act as a vacuum and suck dust into the body. I have decided to get a bag that will fit the camera with a lens attached so that it reduces the times that I have to remove the lens and so open up the camera body. Any other tips?