Auto exposure control at full aperture

For example, with an f/1.4 lens and ASA 100 film, the ELW's automatic shutter will function down to one second with the lens set at 1.4, and propor- tionately slower as the aperture is closed.

Using a standard of ASA 25 film, you may be assured of at least a four second speed regardless of the aperture of the lens used as long as the lens is set at full aperture (refer to Table).

Using ASA 400 at f/l.4, the slowest speed is 1/4 second; however, as the aperture is closed, the functioning shutter speed becomes progressively slower until we reach f/5.6 when the slowest speed of four seconds is functioning.

Auto exposure control with stop-down meter-

ing

When using a bellows or other extension equip- ment, which disengages the meter coupling device, it is necessary to revert to stop-down metering. Certain limitations are imposed in this mode.

As lens-to-film distance is increased, the metering range (EV range) changes proportionately. For

example, when an f/2 lens is used at 2:1

reproduction (twice life-size) the effective f/num- ber is f/5.6. When used at f/8, the effective f/number is f/22.

When pictures are taken under minimal light levels, it is desirable to use a high-speed film (ASA 160 or higher) . Using Tri-X at film speed 400 with stop-down metering, with an effective f/number of f/8, the shutter speed range would be from 1/4 second to 1/1000. Should the light level drop below EV6, it would be out of the shutter speed range of the meter.

Table Slowest shutter speed at full aperture with any lens

ASA speed

Slowest shutter speed

(sec.)

 

 

1600

 

1/15

800

 

1/8

400

 

1/4

200

(160)

1/2

100

( 80)

1

50

( 64)

2

25

 

4

37

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Nikon Elw instruction manual 800 400 200 160 100