Observation device and method of operating an observation device

A method of operating an observation device, in particular an endoscopic observation system, comprising the steps of:

• providing an instrument comprising a shaft having a proximal end and a distal end;
• an objective optics disposed the shaft and having a field of view;
• and an imaging sensor arranged to capture image data, the imaging sensor forming a sensor array composed of evenly distributed sensor elements,
• wherein the objective optics is arranged to project a scene in the field of view to the imaging sensor;
• wherein the objective optics includes an objective lens configured to capture a single image, the objective lens being symmetrical with respect to a main axis, the single image having a central imaging region and a peripheral imaging region within the field of view;
• wherein the objective optics has a focal length in the central imaging region and a focal length in the peripheral imaging region that is different than the focal length in the central imaging region, and wherein the focal length of the central imaging region is essentially constant, and the focal length of the peripheral imaging region is essentially constant so as to generate a first optical imaging resolution in the central region and a second optical imaging resolution in the peripheral imaging region, the first imaging resolution being larger than the second imaging resolution;
• capturing one or more single images, each single image having a wide field peripheral image portion and a central image portion wherein the central image portion is of higher resolution than the peripheral image portion;
• expanding the peripheral image portion to be a same proportion as the central image portion;
• and
• processing the one or more captured images.