There are advantages to both approaches. For the other manufacturers, it means that existing SLR system users can make the switch to digital without having to replace their expensive lens collections, and will be familiar with the controls and handling of their new camera. Brand loyalty is a major feature of the SLR market, and a Canon, Pentax or Nikon user is likely to stay with the same brand for life, spending thousands of pounds on accessories - a highly profitable market of which all the manufacturers would like a part.