Nikon EL2 - Manual (Page 51)

For automatic diaphragm lenses with no coupling ridge,
first set the shutter-speed dial for either automatic or
manual shutter speed selection. When using automatic,
next depress and hold the depth-of-field button to stop-
down the lens diaphragm and adjust the aperture ring
until the black needle indicates the desired shutter speed;
then, while holding the button depressed, press and
hold the memory lock until the completion of the ex­
posure. When using manual operation, select the desired
shutter speed, depress and hold the depth-of-field but­
ton, and (while holding the button depressed) adjust the
aperture ring until the meter needles in the finder over­
lap. Whichever mocJe of operation used, be sure to re­
lease the depth-of-field button prior to making the ex­
posure.
For bellows units, extension rings and preset lenses, set
the camera to the desired shutter speed (or to auto­
matic); then, stop down the lens manually until the me­
ter needles in the finder overlap (or the desired shutter
speed is indicated); when using automatic shutter speed
selection, it may be necessary to press the memory lock
if the aperture is to be re-opened for focusing and/or
composition. Preset-type lenses include PC-Nikkor
lenses.