Canon INON D-180 User Manual page 14

subject reflectivity measured TTL; based on this information, second (main) flash duration is
calculated, and then strobe fires main flash quickly afterwards, only for the specified duration.
(Pre-flash TTL Auto Exposure Adjustment)
3) During exposure, strobe itself measures in real time
Using a light sensor in the strobe, subject reflectivity measured in real time, with strobe
quenching at time of "proper" exposure. (External Auto Flash Exposure Adjustment)
For each of these automatic flash adjustment methods to work, besides a signal instructing the
external strobe to fire, the various combinations of cameras (and master strobes) and external
strobes must be compatible with each other's signal transmission methods.
- In case of 1) above: From Camera to External Strobe
- In case of 2) above: From Camera to External Strobe
- In case of 3) above: From Camera to External Strobe
As of December 2002, a majority of consumer digital cameras use Pre-Flash TTL Auto Exposure
Adjustment. Unlike conventional 35mm film camera systems with the widely adopted Real Time
TTL Auto Flash Adjustment, most current digicams cannot use such automatic exposure
adjustment with external strobes. Likewise, except for some dedicated land strobes for certain
camera brands, there are no external strobes yet available fully compatible of functioning with the
various Pre-Flash TTL Auto Exposure Adjustment type cameras available. The main reasons are:
Because pre-flash specifications and protocol have not been standardized between the camera
manufacturers.
The external strobe to camera signal transmission specifications have not been standardized
between camera manufacturers, and the communication method used by most existing external
strobes has not been adopted in most digital cameras.
Due to the lack of real time information from camera to strobe, digital cameras cannot
automatically adjust exposure with external strobes. Therefore it is necessary for the external
strobe itself, to a certain extent, independently execute automatic flash adjustment.
The D-180, as an External Auto Flash Exposure Adjustment type of strobe, and using an Advanced
Cancel Circuit, is compatible with the vast majority of digital cameras using Pre-Flash TTL Auto
Exposure Adjustment, and of course Real Time Auto Exposure Adjustment type cameras.
Regardless of the camera type, automatic light adjustment is possible with the D-180 external
INON D-180 Manual
Version 1. October 4, 2003
Copyright 2002, 2003 by INON America, Inc. All rights reserved.
External Strobe to Camera
Instruction to stop flash
Instruction to stop flash; or,
Instruction for flash duration
External strobe information
ISO Sensitivity information, and
Aperture Value information
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