Video: Tips for changing an SLR lens
J: When changing a lens, don't do it in a dusty area or of course not in the rain. Keep the body pointed down, since things won't fall into it as easily and never touch anything in here, especially if you have a mirror. Don't touch the mirror. And if you do touch the mirror, don't clean the mirror because it's a polished piece of metal and you will never get it clean. You'll only scratch it more and more. You can go to a professional camera shop and see what they can do with it.
Behind the mirror is a sensor. Some cameras deal with cleaning that sensor different ways. Usually in the menu there's a way to lock up the mirror but turn off the sensor so it's not electrostatically charged. And you can take an air bulb sprayer and blast away the air. And it's only gonna get the surface dust off with a little bulb thing. Don't use compressed air because it's liable to spray some of the solvent and you won't be able to clean that off. If your sensor is really dirty, professional camera shops are the only way to take care of it.
If you have any questions about cameras or camera accessories feel free to give us a call at Crutchfield.