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characteristics, the basic functionality required of external strobes is also different, and the
External Auto strobe functions of the D-180 have been developed to a high level accordingly.
Reference No. 10
Characteristics of External Auto Exposure Adjustment systems
Strobe Beam Axis Adjustment
Adjust strobe beam direction so focus light shines directly on subject. This is necessary so the
flash will illuminate the subject, and also so the light adjustment sensor directly faces the subject
and receives the reflected light. This is important for proper functioning of External Auto type
strobes.
Strobe Position and Beam Angle
As the strobe is positioned farther away from the camera (the angle between the camera lens axis
and the strobe becomes greater), depending on the subject and shooting conditions, the subject
reflectivity that the camera measures compared to what the D-180's light adjustment sensor
measures could be very different and "correct" exposure may not be obtained using External Auto.
In such cases, compensate flash output by adjusting D-180 Aperture Value Set Switch.
Strobe Light Adjustment Timing
Compared to conventional silver halide film camera systems using external strobes with TTL
automatic light adjustment, when using external strobes with External Auto light adjustment, the
strobe itself determines the strobe's output and when to quench (for D-180, in less than 1/1,000 of
a second).
However, even after the strobe flash stops, the shutter may remain open and exposure from natural
ambient light will continue until the shutter closes, especially for non-real-time light adjustment
cameras, such as those using pre-flash. The external strobe does not consider, or calculate for
natural light exposure after the flash stops firing.
Accordingly, for imaging where exposure from natural light is a large proportion of the total
exposure (macro / slow synch / bright conditions etc.), use exposure compensation on the camera,
and/or strobe output compensation on the strobe.
Setting Manual Flash Output
When using strobes there is an intimate relationship between the Aperture Value and the shooting
distance. In air, the following formula may be used to calculate the correct aperture value.
÷
=
Strobe's Guide Number
Distance to Subject
Correct Aperture (at ISO 100)
(GN)
(meter)
(f/)
However, light is absorbed very quickly as it travels through water so that it does not completely
reach the subject as it would in air. Accordingly, it is often advised to open the aperture one or
INON D-180 Manual
44
Version 1.
October 4, 2003
Copyright 2002, 2003 by INON America, Inc. All rights reserved.
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