1. An exposure apparatus that exposes a substrate, comprising: a projection optical system that has a first object field area and a second object field area different from the first object field area and that projects an image of a pattern from a single mask onto a first image field and a second image field, the first object field area and the second object field area corresponding to separate locations on the single mask, an image of the pattern being formed from the single mask in the first image field by exposure light via the first object field area, and an image of the pattern being formed from the single mask in the second image field by exposure light via the second object field area, wherein a first substrate is exposed with the image of the pattern formed in the first image field, and a second substrate is exposed with the image of the pattern formed in the second image field.