Nikon D90 - Manual (Page 257)

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D Notes on Optional Speedlights
Refer to the Speedlight manual for detailed instructions. If the Speedlight supports the Nikon
Creative Lighting System, refer to the section on CLS-compatible digital SLR cameras. The D90
is not included in the “digital SLR” category in the SB-80DX, SB-28DX, and SB-50DX manuals.
If an optional flash unit is attached with the camera in modes other than j, the flash will fire
whenever a photograph is taken. The following flash modes are available:
•
i, k, and n modes: Fill flash and red-eye reduction. Fill flash is automatically selected if the
flash mode is set to off or auto when an optional flash unit is attached. Auto with red-eye
reduction becomes red-eye reduction.
• o mode: Auto slow sync becomes slow sync, auto slow sync with red-eye reduction becomes
slow sync with red-eye reduction, and off becomes slow sync.
i-TTL flash control can be used at ISO sensitivities between 200 and 3200. At values over 3200,
the desired results may not be achieved at some ranges or aperture settings. If the flash-ready
indicator blinks for about three seconds after a photograph is taken, the flash has fired at full
power and the photograph may be underexposed.
The SB-900, SB-800, SB-600, and SB-400 provide red-eye reduction, while the SB-900, SB-800,
SB-600, and SU-800 provide AF-assist illumination. With other Speedlights, the camera AF-assist
illuminator is used for AF-assist illumination and red-eye reduction. When used with AF lenses
with focal lengths of 17–135 mm, the SB-900 provides active AF-assist illumination for all focus
points; note, however, that autofocus is available only with the following focus points:
When used with AF lenses with focal lengths of 24–105 mm, the SB-800, SB-600 and SU-800
provides active AF-assist illumination to assist autofocus for the following focus points:
In programmed auto, the maximum aperture (minimum f-number) is limited according to
sensitivity (ISO equivalency), as shown below:
For each one-step increase in sensitivity (e.g., from 200 to 400), aperture is stopped down by
half an f-stop. If the maximum aperture of the lens is smaller than given above, the maximum
value for aperture will be the maximum aperture of the lens.
When an SC-series 17, 28, or 29 sync cable is used for off-camera flash photography, correct
exposure may not be achieved in i-TTL mode. We recommend that you choose spot metering
to select standard i-TTL flash control. Take a test shot and view the results in the monitor.
In i-TTL, use the flash panel or bounce adapter provided with the flash unit. Do not use other
panels such as diffusion panels, as this may produce incorrect exposure.
17–105 mm 106–135mm
24–34 mm 35–105mm
Mode
Maximum aperture at ISO sensitivity of
200 400 800 1600 3200
P , i, k, l, m, o 4 4.8 5.6 6.7 8
n 8 9.5 11 13 16