Settings that must be set before you can use the external flash

You need to set the flash to slave and the same channel as the master. If the flash doesn't have this function it may be able to be fired optically. Set the master flash to low power and set the off camera flash to optical.

there are advanced color correction modes,
Blue or dark pictures/videos
Keep your shooting distance inside of 2ft to 3ft, depending on
visibility and ambient light.
If you are using only one light, considering adding another light
(dual lights) or/and external flash accessory. The ideal
set-up is a combination of a light plus flash.
Consider purchasing the SeaLife Wide Angle Lens (SL975). The
fisheye lens allows you to get closer to the subject and fit more
into to picture frame.

For SeaLife camera with external light accessory (No external flash):
1) Set the camera's scene mode to Sea mode or Snorkel mode
2) Change camera's PHOTO and VIDEO White Balance
settings to DAYLIGHT.
For SeaLife camera with external light and flash accessories:
1) Set the scene mode to Ext. Flash mode
2) Change the VIDEO White Balance setting to DAYLIGHT.
For other underwater camera brands:
1) Set the Scene mode to "Auto" or "Underwater" scene
mode, as recommended by the camera manufacturer.
2) You may also need to change the White Balance setting to
DAYLIGHT depending on the camera's underwater color
correction or if pictures/video turns out red.

You have to set the on board flash you may have external fllash set on even if you reset your camera go to menu then flash/bracketing then TTL set for flash on camera

The camera does not flash. Solution
Follow this procedure to troubleshoot the camera not flashing.

1. Select the correct flash mode . NOTE: When set to the Forced Flash setting, the camera should flash for all still pictures.
   
2. Perform a reset procedure .

The troubleshooting steps listed above should resolve your issue. If you have completed all of the steps and the issue is not resolved, service may be required. The Sony® eService Web site at http://eservice.sony.com/ can assist you in obtaining service from a Sony Service Center or locating a Sony Authorized Servicer.
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How to troubleshoot an external flash that will not work. Solution
IMPORTANT: Depending on the mode of the camera, the external flash may not be available. Refer to the instruction manual of the camera for more information.

1. Ensure the external flash is properly inserted into the accessory shoe on the camera.
2. If using the connection cord, ensure it is properly attached.
3. If the external flash uses batteries, ensure fresh batteries are installed.
4. Ensure that the POWER switch on the external flash is set to ON .
5. Ensure the hot shoe setting on the camera is properly set for the type of external flash and camera being used. NOTES:
   
   • When using a commercially available standard external flash, ensure the hot shoe is turned on.
   • If a Sony external flash is being used with an advanced hot shoe on a Sony camera, ensure the hot shoe is turned off.
   • It may be necessary to refer to the instruction manual of the camera and external flash for specific information about the hot shoe.
6. Ensure the READY lamp on the external flash is illuminated.

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Cybershot Digital Still Camera Mavica Last Modified Date: 03-04-2010ID: C292057 document.write("");

External flash can be activated in P, S, A and M mode.
Press Menu/OK and use the > until you get to External Flash, and activate it there. Press OK to end.

Yuo can use external flash in P, S, A and M mode.
To activate the externale flash mode, press Menu/OK and use > to cycle through the different options. Switch External Flash to On. Press OK.

I haven't heard of this problem but compliments of velocityreviews I came up with this. Follow the instructions below to attach an external Speedlight. Refer to your Speedlight manual for detailed instructions regarding Speedlight operation. 1 Make sure that both the camera and the external Speedlight are turned off. 2 Attach the Speedlight to the camera accessory shoe. 3 Turn both the camera and the Speedlight on. 4 Set the external Speedlight zoom head to an angle wider than 28 mm. If you are using a Speedlight with Auto Power Zoom, set the zoom head angle manually. The COOLPIX5700 does not support power zoom. 5 Set the external Speedlight flash mode to TTL. At this setting, the amount of light produced by the external Speedlight is measured by the camera?s photocell, and the flash shooting range adjusted automatically to ensure optimal exposure. D-TTL flash control (available with the SB-80DX, SB-50DX and SB-28DX) is not supported. 6 Take the picture If the Speedlight Options: Speedlight Control option in the SET-UP menu is set to Auto, only the external Speedlight will fire. If this option is set to Int & Ext Active then the external Speedlight and the builtin Speedlight will fire at the same time. The COOLPIX5700 does not support AF-assist illumination, or red-eye reduction using the red-eye reduction lamp on the external Speedlight. At a setting of STBY (standby), the Speedlight will turn on automatically whenever the camera turns on but will not turn off automatically when the camera turns off. Exact functionality varies with the Speedlight in use. Refer to your Speedlight manual for details. I hope it's of some help BMW

t is my understanding that you must use manual exposure (shutter and aperture) with an external flash. This shouldn't be a problem (set the camera to the settings on the guide chart that comes with your flash, and let the flash worry about the strength/flash duration necessary - provided it is an "auto" flash with a sensor)... I'm going to use a Vivitar 273 with my Epson 3000z... There are a few other threads on this forum regarding External Flash use.

Yes, set the camera mode dial to P, A/S/M or any shooting mode except the movie mode. Turn on the extension flash unit's power then select the camera's flash mode. The flash mode button on the camera controls the built-in flash as well as the extension flash. Only the built-in flash and the Olympus FL-20/FL-40/FL-50 extension flash can use the red-eye reduction flash mode. All flash units can use the fill flash, flash off, and slow-sync flash modes.

Yes, set the camera mode dial to P, A/S/M or any shooting mode except the movie mode. Turn on the extension flash unit's power then select the camera's flash mode. The flash mode button on the camera controls the built-in flash as well as the extension flash. Only the built-in flash and the Olympus FL-20/FL-40/FL-50 extension flash can use the red-eye reduction flash mode. All flash units can use the fill flash, flash off, and slow-sync flash modes.