Digital single lens reflex cameras (DSLRs) combine the advantages of SLRs with those of digital cameras since they have an image sensor instead of a film in the image plane, and a digital image memory. These cameras are the flagships of modern camera marketing. Early models were very expensive, only affordable by professional photographers. Nowadays a great variety of cameras are on the market, mostly DSLRs for interchangeable lenses, especially lenses for existing autofocus SLR lens mounts of the most successful SLR product lines of the past. Exceptions are some camera models with fixed lens. A new trend is to make DSLRs for new autofocus lens mounts. The first one is the Four-Thirds (4/3) mount (see also 4/3 category).