Projection system and projector

A projection system comprising:

• a relay system that focuses light having exited through a first image plane on a second image plane;
• an enlarging system that enlarges and projects an image focused on the second image plane on a third image plane;
• and
• a light level adjusting member comprising a diaphragm which adjusts an amount of light which exits the first image plane,
• wherein the relay system includes:
• a first lens element on which the light having exited through the first image plane is incident, the first lens element having positive refracting power,
• a reflective member that reflects a light having passed through the first lens element, the reflective member having positive refracting power, and
• a second lens element on which a light reflected off the reflective member is incident and which focuses the light reflected off the reflective member on the second image plane, the second lens element having positive refracting power,
• wherein the light level adjusting member is positioned in a vicinity of a surface of the reflective member,
• wherein the second image plane is inclined with respect to the first image plane by an angle which is not zero.