Nikon F4 Body Only, F4S instruction manual Mirror Lockup Lever

MIRROR LOCKUP LEVER

Ahighly efficient, tungsten-alloy shutter balancer is incorporat- ed in the shutter unit. The balancer operates during shutter operation to overcome vibration normally caused by the shutter curtain in other cameras.

When using super-telephoto lenses or doing photomicrogra- phy, it is necessary to reduce camera vibration to the absolute minimum. To lock the reflex viewing mirror in the "up" position, push in the depth-of-field preview button and rotate the mirror lockup lever counterclockwise until it stops.

With the mirror locked up, you cannot operate the camera in any Auto Exposure or autofocus mode, even though the view- finder LCD may indicate otherwise. Any indication of light by the LCD is a result of spurious light entering through the viewfinder eyepiece.

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