Why didn’t Nokia implement a continuous autofocus system for video?
The Nokia N8 is our first product to use an Active Hyper Focal Distance system. We have used hyper focal distance before but in the case of the Nokia N8 where the HD video demands greater focus precision, we needed to improve the dependability. Many mobile phones which include autofocus use driving systems which rely on friction to a certain degree. However, in some cases after the lens has been driven to the desired position, it can ‘slip’ causing a shift in focus. For this reason, we use an ‘Active’ system where we constantly measure the position of the lens and readjust it to maintain the hyperfocal distance if required. The use of this system allows us to provide sharp and highly detailed videos from approximately 60cm to infinity, without the need for focus adjustment. Other systems may provide benefits for shooting at closer distances but in our evaluation, we found this to be less dependable in the vast majority of recording situations which are typically at distances greater th
