FullFocus or EDoF (Enhanced Depth of Field), rather than having an expensive auto-focus mechanism, the idea is that a cheaper fixed focus camera can be dramatically improved by using a custom lens which has been designed to focus the RGB components of light differently. When an image is captured (effectively three 'photos', one for each of the RGB components), every part of the photo's viewing area is analysed, with the sharpest of the RGB images determining the detail used for that part, with the other image supplying appropriate coloration. In this way, the normal depth of field for a fixed focus camera is extended and objects a metre or so away can be captured fairly sharply, something which wouldn't be possible with a vanilla fixed focus camera.

The depth of field of an imaging system is the distance in the object space in which objects are considered to be in focus. As such, extending the depth of field of an imaging system will extend the distance over which objects are in focus. Traditionally, increasing depth of field is performed by decreasing the size of, or stopping down, the aperture of the lens. This method, however, drastically reduces the amount of light gathered. For example, stopping down a lens one F-stop reduces the amount of light passing through the lens by a factor of two.

So, instead of using auto-focus, this camera comes with idea of getting the fixed focus with custom lens that designed for focusing differently RGB components of light, in other words, EDoF (Or EDF) does Auto Focus “automatically” without that looping back and forth trying to get the focus right. It should be much better than the normal Auto Focus wich it means it is able to produce 'more focused' images than standard fixed focus camera. It not quite as good as a full auto focus system, but it is a lot closer and is cheaper to implement. While there are some requirements in the lens the majority of the work is done by software.

According to rumors, the full focus feature in these models comes from Tessera.

Source : allaboutsymbian (here and here), meyerinst