2. D850 Online Manual
3. Using Shoe-Mounted Flash Units
4. Flash Modes

The camera supports the following flash modes:

Front-curtain sync

This mode is recommended for most situations. In programmed auto and aperture-priority auto modes, shutter speed will automatically be set to values between 1/250 and 1/60 s (1/8000 to 1/60 s with Auto FP High-Speed Sync; 0 Auto FP High-Speed Sync).

Red-eye reduction ¹

If flash unit supports red-eye reduction, choose this mode to reduce “red-eye” effect sometimes caused by flash. Not recommended with moving subjects or in other situations in which quick shutter response is required. Do not move camera during shooting.

Red-eye reduction with slow sync ^{1, 2}

Combines red-eye reduction with slow sync. Use for portraits taken against a backdrop of night scenery. This mode is only available in programmed auto and aperture-priority auto exposure modes. Use of tripod is recommended to prevent blurring caused by camera shake.

Slow sync ³

Flash is combined with shutter speeds as slow as 30 s to capture both subject and background at night or under dim light. This mode is only available in programmed auto and aperture-priority auto exposure modes. Use of tripod is recommended to prevent blurring caused by camera shake.

Rear-curtain sync ⁴

In shutter-priority auto or manual exposure mode, flash fires just before the shutter closes. Use to create effect of a stream of light behind moving objects. In programmed auto and aperture-priority auto, slow rear-curtain sync is used to capture both subject and background. Use of tripod is recommended to prevent blurring caused by camera shake.

Flash off

Flash does not fire.

Choosing a Flash Mode

To choose the flash mode, press the W (M) button and rotate the main command dial until the desired flash mode is selected in the control panel: