Patent ID: 9625687
Date: 2017-04-18
CPC Classifications: G02B,H04N

Claim:
1. An image pickup apparatus comprising: a zoom lens, and an image pickup element arranged on the image side of the zoom lens, wherein the image pickup apparatus has an image pickup surface and converts an image formed by the zoom lens into an electrical signal, the zoom lens comprises a first positive lens unit having a positive refractive power located closest to the object side, a first negative lens unit having a negative refractive power arranged on the image side of the first positive lens unit, and an image side lens unit group arranged on the image side of the first negative lens unit, the first positive lens unit is located closer to the object side at the telephoto end than at the wide angle end, the distance between the first negative lens unit and the first positive lens unit is larger at the telephoto end than at the wide angle end, the distance between the image side lens unit group and the first negative lens unit varies during zooming from the wide angle end to the telephoto end, the image side lens unit group comprises a second positive lens unit having a positive refractive power and a third positive lens unit having a positive refractive power and arranged closer to the image side than the second positive lens unit, the distance between the second positive lens unit and the first negative lens unit is smaller at the telephoto end than at the wide angle end, the distance between the third positive lens unit and the second positive lens unit varies during zooming from the wide angle end to the telephoto end, the first positive lens unit comprises a plurality of positive lens and at least one negative lens, an aperture stop is arranged between the first negative lens unit and a portion of the image side lens unit group, at the telephoto end, the aperture stop is located closer to the object side than a position of a surface vertex of a lens which is positioned closer to the object side among lenses in the image side lens unit group, and the following conditional expressions (2) and (3) are satisfied: where f t is the focal length of the entire zoom lens system at the telephoto end, f w is the focal length of the entire zoom lens system at the wide angle end, IH MAX is the largest image height of the image formed on the image pickup surface or the largest value thereof if the value of the largest image height varies, TL t =TZL t +FB t , where TZL t is the distance on the optical axis from the object side surface to the image side surface of the zoom lens at the telephoto end, and FB t is the back focus of the zoom lens at the telephoto end expressed in the equivalent air distance.