Patent ID: 6424465
Filing Date: 2002-07-23
Classification: G02B

Abstract:
A front tele-converter having an afocal magnification higher than 1.9, which is detachably mountable to a photo-taking lens on its object side, wherein:said front tele-converter has, in order from the object side, a positive lens group (GF) having a positive refractive power and a negative lens group (GR) having a negative refractive power; the positive lens group (GF) has a positive cemented lens; the negative lens group (GR) has a positive lens with its convex surface facing the image side; and the lens groups fulfill the condition of: 0.5F/|fR|<10.0 where a focal length of the negative lens group (GR) is represented by fR, and an effective aperture of a lens surface of the positive lens group (GF) on its side closest to the object side by &PHgr;F.