Optical assembly for a compact wide field of view digital camera with low first lens diameter to image diagonal ratio

A digital point action camera, comprising:

• (a) an optical assembly, comprising from object end to image end:
• a first optical group including two or more lens elements configured to collect and reduce a field angle of light incident at a field of view in excess of 120 degrees;
• a second optical group including two or more spaced apart lens elements;
• a third optical group including two or more lens elements, wherein at least one lens element of the third optical group includes an aspheric surface that is configured to correct higher order astigmatism;
• and
• an aperture stop between said second and third optical groups,
• wherein a ratio of a diameter of a first lens element at the object end of the optical assembly to an image diagonal is less than approximately 3,
• wherein the optical assembly comprises a MTF at Nyquist frequency approximately 200 line pairs per millimeter above 0.35 and a MTF at half Nyquist frequency approximately 100 line pairs per millimeter above 0.55;
• and
• (b) an image sensor disposed approximately at a focal plane of the optical assembly;
• and
• (c) a digital camera housing including electronics and a user interface, and containing said optical assembly and said image sensor in optically effective relative disposition.