Projection system and projector

A projection system comprising a first lens group having negative power, a second lens group having positive power, a third lens group having positive power, a fourth lens group having negative power, a fifth lens group having positive power, a sixth lens group having positive power, and a seventh lens group having positive power that are sequentially arranged from an enlargement side toward a reduction side,

• wherein the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group are moved with the first lens group and the seventh lens group fixed to change the magnification of the projection system, and
• the projection system satisfies the following conditional expressions,
• 1.
• <
• Fg
• ⁢
• 2
• /
• Fw
• <
• 3.
• (
• 1
• )
• -
• 2.5
• ≤
• Fg
• ⁢
• 2
• /
• Fg
• ⁢
• 1
• <
• -
• 1.
• (
• 2
• )
• 0.5
• ≤
• Fg
• ⁢
• 2
• /
• Fg
• ⁢
• 3
• <
• 1.
• (
• 3
• )
• Ft
• /
• Fw
• >
• 2.
• (
• 4
• )
• where Fw represents a focal length of the overall projection system operating at a wide angle end, Ft represents the focal length of the overall projection system operating at a telephoto end, Fg1 represents a focal length of the first lens group, Fg2 represents a focal length of the second lens group, and Fg3 represents a focal length of the third lens group.