A digital camera apparatus has a sensing surface that captures images at a first resolution. A derivative of the captured image is displayed at a viewfinder or stored in a memory, after encoding, with a second, generally lower resolution. The resolutions are related by a downscale ratio. A method for digitally imaging a scene includes providing an imaging lens and a digital image sensing surface such as a CCD sensing surface, and changing a focusing of the lens with respect to the sensing surface in correspondence with a variance of a parameter that relates a captured image at the sensing surface and another image deriving from the captured image. Preferably, the variance of the parameter is the downscale ratio. The focusing of the lens with respect to the sensing surface may be changed by changing the physical distance or by changing a shape of the lens, for example. Apparatus and computer program products are also detailed.