Nikon F25B Photomatic Instruction Manual page 29

For automatic diaphragm lenses with no coupling prong,
su ch as the Zoo m-Ni kkor 200 -600mm f/9.5 lens a nd
sup er-te lephoto lenses using Niko n foc using un its, se t
t he camera to th e des ired shu tter speed; t hen, depress
th e d ep th-of-ficld p review b u tto n
to
stop-dow n the lens
di aphragm a nd, whil e ho lding th e bu tto n depressed,
adjust th e a pertu re rin g until t he ce nter LED indicato r
comes o n. Bc su re to release t he de pth-of-fic ld butto n
pri o r to mak ing th e ex posure.
For bellows units, extension rings and preset lenses , set
the ca me ra to t he d es ired shu tte r spee d; t hen, sto p dow n
th e lens ma nu a ll y until th e cen ter LED indicator comes
o n. Preset-t y pe lenses in clud e PC- Ni kkor len ses.
29