The invention discloses a lens
system and a lens to solve problems that in the prior art, the
image plane of the lens is small, and a constant diaphragm cannot be realized. The lens
system comprises afirst fixed lens combination, a zooming lens combination, an aperture diaphragm, a second fixed lens combination, a focusing lens combination, and a third fixed lens combination in sequence along anoptical axis from an object side to an image side, the change of the
focal length of the lens
system is realized through the position change of the zooming lens combination and the focusing lens combination along the direction of the
optical axis, and the
focal length f2 of the zooming lens combination, the
focal length f3 of the second fixed lens combination, the focal length f4 of the focusing lens combination, the short focal length fw of the lens system, and the long focal length ft of the lens system satisfy conditions shown in the description, wherein a, b, c, d, e and f are constants. According to the lens system and the lens, the dimension of the
image plane of the lens combination is greater than a set value, and the diaphragm of the lens combination is constant.