Plenoptic lens unit providing refocusable imaging mode

A plenoptic lens unit for use with a digital camera system, the digital camera system including a camera body, an image sensor mounted in the camera body having a plurality of sensor pixels for capturing a digital image, and a removable imaging lens, wherein the removable imaging lens is attachable to the camera body and can be used to form an image of a scene onto the image sensor thereby providing a high-resolution non-refocusable imaging mode, the plenoptic lens unit being useful for providing a low-resolution refocusable imaging mode and comprising:

• a lens housing having a lens mounting interface for mounting the plenoptic lens unit to the camera body;
• a microlens array with a plurality of microlenses mounted in the lens housing;
• and
• an imaging lens for forming an image of the scene onto an image plane that is substantially coincident with the microlens array, the imaging lens having an imaging lens aperture;
• wherein the plenoptic lens unit can be mounted on the camera body such that the microlens array is positioned between the imaging lens and the image sensor to provide the low-resolution refocusable mode.