Karutz clamped them firmly to my head, tight enough to block out the light.

NEWYORKER: The Visionary

Sandwiching the solar cells inside the device would block some light out and knock down power conversion efficiency even further, Filler cautioned.

FORBES: Magazine Article

The dedicated bayonet lens hood (LH3-01) can be attached to block out extraneous light.

ENGADGET: Sigma DP3 Merrill packs a Foveon X3 sensor and a fixed F2.8, 75mm-equivalent lens