Endoscopes, multicore endoscope fibers and configuration and operation methods are provided. The fibers may have hundreds or thousands of cores and possibly incorporate working channel(s) and additional fibers. The fiber may be used at different optical configurations to capture images of tissue and objects at the distal tip and to enhance a wide range of optical characteristics of the images such as resolution, field of view, depth of field, wavelength ranges etc. Near-field imaging as well as far-field imaging may be implemented in the endoscopes and the respective optical features may be utilized to optimize imaging. Optical elements may be used at the distal fiber tip, or the distal fiber tip may be lens-less. Diagnostics and optical treatment feedback loops may be implemented and illumination may be adapted to yield full color images, depth estimation, enhanced field of views and/or depths of field, and additional diagnostic data.