Projection objective having four groups for projecting light onto a projection surface and a projector including the projection objective

A projector for producing an image on a projection surface with a light source comprising:

• an image transmitter for modulating light;
• and
• a projection objective for projecting the light from the light source onto the image transmitter;
• wherein the projection objective comprises:
• a first group with a negative meniscus;
• a second group with positive refractive power;
• a third group with a single lens;
• a fourth group with a lens with positive refractive power, and a field lens with positive refractive power, such that the light passes through the projection objective from the fourth to the first group;
• wherein the common focal length of the fourth group and the field lens is smaller than twice the image circle diameter of the projection objective;
• wherein the maximum free diameter is smaller than the overall focal length and in particular smaller than approximately 0.8 times the overall focal length of the projection objective;
• and
• wherein the field lens is positioned at substantially one fifth of the overall focal length of the projection objective from the image transmitter.