Notes on Optional Speedlights
Refer to the Speedlight manual for detailed instructions. If the Speedlight supports the Creative Light- ing System, refer to the section on CLS-compatible digital SLR cameras. The D40 is not included in the “digital SLR” category in the SB-80DX, SB-28DX, and SB-50DX manuals.
If an optional Speedlight is attached with the camera in 
, 
, 
, 
, 
, 
, or 
mode, the built-in flash will turn off and the optional Speedlight will fire whenever a photograph is taken. The following flash modes are available:
•
, 
, 
, 
, 
, and 
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 Speedlight is attached. Auto with red-eye reduction becomes red-eye reduction.
•
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.
The optional Speedlight will not fire when the camera is in 
mode.
If AUTO is selected for ISO sensitivity in 
, 
, 
, 
, 
, 
, or 
modes or On is selected for Custom Setting 10 (ISO auto) in P, S, A, or M mode, ISO sensitivity will be adjusted for optimal flash output when an optional SB-400, SB-800, or SB-600 Speedlight is attached. This may result in foreground subjects being underexposed in photographs taken with the flash at slow shutter speeds, in daylight, or against a bright background. Choose a flash mode other than slow sync or choose a larger aperture.
The shutter will synchronize with an external flash at speeds of 1/500 s or slower.
i-TTL flash control can be used at ISO sensitivities between 200 and 1600. Higher values may not pro- duce the desired results at some ranges or apertures. 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-400, SB-800, and SB-600 provide red-eye reduction, while the SB-800, SB-600, and SU-800 pro- vide AF-assist illumination (the SU-800 does not provide AF-assist illumination in close-up mode). With other Speedlights, the camera AF assist illuminator is used for AF-assist illumination and red-eye reduction. If the controls on the SB-800, SB-600, or SU-800 are used to adjust flash compensation, 
will appear in the camera shooting information display.
In the following modes, the maximum aperture (minimum f/-number) varies with ISO sensitivity:
| | Maximum aperture at ISO sensitivity of | |
Mode | 200 | 400 | 800 | 1600 |
| | | | |
P, , , , , , | 4 | 4.8 | 5.6 | 6.7 |
| 8 | 9.5 | 11 | 13 |
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 aper- ture 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 stan- dard i-TTL flash control. Take a test shot and view the results in the monitor.
In i-TTL mode, use the flash panel or bounce adapter provided with the Speedlight. Do not use other panels such as diffusion panels, as this may produce incorrect exposure. Auto power zoom is available only with SB-800 and SB-600 Speedlights.
