Patent ID: 7173777

Claim:
A wide-angle projection lens comprising the following components in sequential order from an image side: (a) a first lens group of negative refractive power, the first lens group having at least one aspheric surface; (b) a second lens group; (c) a third lens group of positive refractive power; and wherein the following Conditions (1) to (4) are satisfied: | F 1 /F|â‰§ 4.5â€ƒâ€ƒCondition (1) 2.5â‰¦| F 2 /F|â‰¦ 6.0â€ƒâ€ƒCondition (2) 3.8â‰¦| F 3 /F|â‰¦ 5.0â€ƒâ€ƒCondition (3) 0.8â‰¦ BFL/Fâ‰¦ 1.4â€ƒâ€ƒCondition (4) where F is the focal length of the wide-angle projection lens; F 1 is the focal length of the first lens group; F 2 is the focal length of the second lens group; F 3 is the focal length of the third lens group; and BFL is the back focal length.