Nissin i40 Instruction Manual page 12

Joy of Flash Photography
TTL flash power compensation
With the latest TTL flash control system, the flash power level is always
automatically controlled by the camera for the most appropriate exposure. If
you wish, if you can soften or weaken the flash light, or give more light to the
subject without changing the environmental or background exposure effect.
The i40 can make it possible to quickly adjust the exposure for each particular
flash picture as needed.
Set i40 to the camera's hotshoe and press the on/ off switch to power on.
Indicator Lamp A on.
Rotate the Function dial to "TTL" mode.
Indicator Lamp C on.
To set the Flash power compensation level rotate
the Power dial to the power level you desire.
TTL flash power compensation is provided in 9 steps
by half Ev increments for -2.0, -1.5, -1.0, -0.5, 0, +0.5,
+1.0, +1.5 and +2.0 Ev.
Take a picture and the subject is shown with required lighting effect by keeping
the background exposure level as originally expected.
On some cameras, the TTL flash power compensation setting is provided in its
menu mode. When setting the TTL flash power compensation on your camera,
any compensation which is also set on the i40 will be counted in addition to the
compensation you selected in the camera's menu mode. ( i.e. Having a +1
compensation set on the flash and a +1.3 compensation set in the camera would
yield a total compensation of +2.3 EV.)
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