1. A method which involves use of multiple optical chains of a camera device, said multiple optical chains including at least a first group of optical chains and a second group of optical chains, the method comprising: capturing images using both said first group of optical chains and said second group of optical chains during a first time period during which focal lengths of optical chains in said first and second groups of optical chains remain fixed; changing a focal length of optical chains in said first group of optical chains from a first focal length to a second focal length during a second time period; capturing images using said second group of optical chains during said second time period, optical chains in said second group of optical chains having a focal length which remains unchanged during said second time period while the focal length of optical chains in said first group is changed; generating a first composite image from multiple images captured during said first time period; and generating a second composite image from images captured during said second time period by said second group of optical chains.