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INON D-180 Manual
Version 1. October 4, 2003
Copyright 2002, 2003 by INON America, Inc. All rights reserved.
16
In general, for “Pre-flash TTL Auto Exposure Adjustment” type camera systems, before the shutter
opens to actually record the image, the subject reflectivity must be metered in order to calculate the
main flash duration (intensity).
In order to meter the subject reflectivity, the camera fist fires one or more small flashes
(pre-flashes) and measures the light reflected back from the subject. Then the camera calculates
what it “thinks” the best main flash duration would be to achieve correct exposure. Finally, the
shutter opens and the camera’s internal strobe fires its main flash for the pre-calculated duration.
Reference No. 4 “External Auto”
(External Automatic Flash Exposure Adjustment)
A function where a strobe has a light adjustment sensor mounted in the strobe itself, whereby the
light adjustment sensor adjusts flash output based on subject reflectivity, for “correct” exposure.
For strobes with this function, by setting the strobe’s Aperture Value to match that of the camera
system, at the same time as the camera’s internal strobe fires its main flash, the external strobe’s
light adjustment sensor measures subject reflectivity in real time, and automatically adjusts for
correct strobe output.
Reference No. 5 “Master Strobe” and “Slave Strobe”
“Master” and “Slave” are terms corresponding to “which strobe is the controlling device” and
“which strobe is being controlled”.
When using two strobes (including the case of the camera’s internal strobe and the D-180), where
both the camera’s strobe and D-180 are directly connected to the camera/housing, and are
controlled by the same signal, since there is no difference in function, there is no distinction
between Master and Slave.
However, it is possible to connect only one of the strobes directly to the camera/housing, with the
other strobe connected to the first strobe. The strobe connected to the camera/housing (Master)
receives control signals directly from the camera and flashes. At that time, the other (Slave)
strobe sees the master strobe’s flash, and at that signal, reproduces the same flash duration as the
master strobe. “Master” and “Slave” terms are used when the two strobes have such definite
master/slave relationship.
For the purpose of compatibility with the D-180, as of December 2002, most digital camera’s
internal strobe is the master strobe, with the external strobe being a slave connection.
Reference No. 6 “Advanced Cancel Circuit”
By proactively utilizing the fundamental light control theory of digital cameras using “Pre-flash
TTL Auto Flash Adjustment”, compared to conventional strobes with simple pre-flash cancel
circuits which cause the camera’s internal strobe to emit a full discharge on the second main flash,