The performance of a telescope is generally determined by its resolving power and light-gathering power. Resolving power is the ability to distinguish minute objects, and light-gathering power is the ability to gather light. In the case of a reflector telescope, these two factors are greatly affected by the accuracy of the primary mirror.

NAYUTA's primary mirror is two meters in diameter, and is Japan's largest, as well as the world's largest mirror attached to a ground-based telescope. The surface of the mirror is polished to extreme accuracy. In a matter of speaking, it is about the same as leveling a huge baseball field to an accuracy of two microns (1/30th of a strand of hair). Such precision is what it takes to achieve superior performance.