Nikon Speedlights let the photographer choose between two different TTL modes: a plain TTL mode, and the TTL BaLanced fill (TTL BL) mode.

尼康高速闪光灯有两种不同的TTL模式：普通ttl模式和TTL均衡补充(TTL BL)模式。

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The TTL BaLanced fill (TTL BL) mode is the most complicated flash mode on the Nikon Speedlights. This mode is (so far) not found on any third party flash units.

TTL均衡补充（TTL BL）模式是尼康高速闪光灯最复杂的模式，该模式（目前）还没有其它闪光灯使用。

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The P7700's hot shoe allows for compatibility with Nikon Speedlights (SB-910 and SB-700) as well as the GP-1 GPS unit and ME-1 external stereo microphone.

ENGADGET: Nikon intros flagship Coolpix P7700 for prosumers, diminutive Coolpix S01 for fashionistas

The new Nikon HD-SLR is also a gateway to Nikon's renowned Creative Lighting System (CLS) which illuminates a whole new world of creative image making using multiple Speedlights.

ENGADGET: Nikon unveils lightweight, full-frame D600 DSLR -- hands-on and low-light samples (video)