MIRROR LOCKUP
The reflex mirror must be locked in the up position when using either the Fisheye-Nikkor 6mm f/5.6 or the OP Fisheye-Nikkor 10mm f/5.6 lenses, since their rear elements protrude into the camera body and interfere with mirror movement. Locking up the mirror is also necessary when changing the battery mounted in the chamber at the bottom of the mirror box. To lock up the mirror, turn the mirror lockup lever upward as far as it will go (approx. 45°). The mirror will remain in the up position until the lever is returned to the normal po- sition.
Note: The mirror lockup lever function can be duplicated by using the self-timer to trigger the camera, as the timer action causes the mirror to swing up at the start of the countdown process. This is convenient particularly when minimization of mirror shock is desired, without the need to actually lock the mirror up, as in photomicrographic applications.
