Few can be unimpressed by the quality of pictures coming back from the NASA Spirit Mars rover. But did you know Spirit only has a 1 megapixel digital camera? The CCD is just 1,000×1,000 pixels. When you compare this to the 6 megapixel cameras readily available in high street camera shops, just how does Spirit get such good pics? The answer is in the lens. In any digital camera the lens is one of the major determinants of picture quality. Most consumer digital cameras have relatively cheap lenses. Stick on a top notch lens and even the most modest of cameras can take better pics. True, Spirit also uses a CCD with a higher spec than those used in your average Sony Cybershot but it's still way below the maximum resolution of consumer cameras. The secret of Spirit's success are its lenses. If you're buying yourself a digital camera in the January sales then go for one that accepts replacement lenses. You might not be able to afford the kinds of hardware NASA uses but you can still improve the quality of your pictures by carefully selecting the lenses you can afford.