Nikon F3AF instruction manual Stop-down metering

for ASAIISO 100 in Section B, and go down diagonally until the protruding line intersects with Section C's vertical line for a shutter speed of 1/2000 sec . (the F3AF'sfastest shutter speed) this time. Then follow the horizontal line that leads to Section D's EV value for ASA/ISO lOa, and you will get a reading of EV

16.This means that at an flstop of 1/5.6 at ASAIISO 100 and at shutter speeds from 8 to 1/2000 sec ., the effective metering range is EV 2 to 16, which is well within the F3AF'smetering range of EV 1 to EV 18.

The green area in Chart 1 encompassed by the heavy lines in Section C demonstrates the usable shutter speed range to match any film speedlaperture combination at ASAIISO 100. (The minimum aperture of the lens is 1/16.)

Similarly in Chart 2, the usable range (at ASAIISO 100) for the AF -Nikkor 80mm f/2.8lens is shown in green .

Two red lines in Section C of both charts indicate the EV value ranges of the scene brightness usable with autofocus or focus- aid operation . Therefore, the combinations of shutter speeds and apertures indicated in the areas outside the lines are not usable.

Stop-down metering

For stop -down metering, Section A indicates the usable EV range for various aperture settings. For example, if the lens is stopped down to f/8 at ASAIISO lOa, refer to the f/8 column in Section A and the EV values indicated for ASAIISO 100 in section D, and you will find that the EV range for f/8 is EV 6 to

23.Now single out f/8 at ASAIISO 100 in Section B. Go diag - onally down until the protruding line intersects with Section C's vertical line for the shutter speed of 8 sec . From this point of intersection , follow the horizontal line that leads to Section D's EV value for ASAIISO lOa, and you will obtain an EV reading of

3.This means that an flstop of f/8 at ASAIISO 100 and a shutter speed of 8 sec. give an EV value outside the metering range . To find out the slowest shutter speed usable, follow the f/8 indi- cation for ASAIISO 100 in Section B diagonally down until it intersects the horizontal line in Section C that leads to Section D'sEV value of 6 for ASA/ISO 100, and you will find that the slowest shutter speed usable is 1 sec. In other words, at f/8 at ASAIISO lOa, the available shutter speed range from 1 to 1/2000 sec. has an effective EV range from EV 6 to 17 (indicated by the broken line in Section C)-well within the metering range .

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