The present technology relates to a technical field of a zoom lens, which has a high zoom ratio and a sufficient speed throughout the entire zoom range and is capable of achieving a sufficient increase in an imaging angle of view, and an imaging apparatus using the zoom lens.
Recently, as the market of imaging apparatuses such as the digital still camera has increased, users have varied demands for digital still cameras. In addition to an increase in image quality and a decrease in size, demand for an increase in the magnification of a photography lens and an increase in the imaging angle of view has also increased.
As a zoom lens used in such imaging apparatuses, there is a positive lead type zoom lens of which a lens group closest to the object side has a positive refractive power. The positive lead type zoom lens is advantageous in an increase in a zoom ratio and is advantageous in that the optical system can be designed so as to be fast across the entire zoom range. Hence, for example, the positive lead type zoom lens has been widely used as a lens appropriate for a high-power type zoom lens in which the zoom ratio is greater than five times.
In particular, as a positive lead type typical zoom lens, there is a well-known zoom lens which is formed of four lens groups having positive, negative, positive, and positive refractive powers arranged in order from the object side to the image side (for example, refer to Japanese Unexamined Patent Application Publication No. 2005-62228 and Japanese Unexamined Patent Application Publication No. 2007-171248).
USPTO Backgrounds
USPTO Backgrounds