E-TTLⅡ technology
High-speed sync
Wireless multiple flash
Slow sync
FE lock
Versatile Functions
Macro Shooting
Lighting Techniques
Product Lineup
Flash Terminology
Slow sync
Light and subject merge to create an unforgettable image.
Slow-sync     EF24-105mm f/4L IS USM, 1.5sec., f/4
Slow-sync flash is ideal for night scene portraits.
image:Regular flash without slow-sync
Regular flash without slow-sync
When photographing people against illuminated buildings, city lights, the setting sun, or dimly lit backgrounds, there emerges a large gap between the brightness of the subject and background. In such situations, it is easy to make mistakes such as overexposing the subject or underexposing the background. But EX Series Speedlites can accurately assess the situation and bridge the brightness gap, providing natural lighting results.
Tips on slow-sync flash
・ Primarily use Aperture Priority AE (automatic exposure) mode
In the Full Automatic and Program AE (P) shooting modes, EOS cameras prioritize securing a fast shutter speed (no slower than 1/30 sec.) to prevent camera shake. Selecting the Aperture Priority AE (Av) mode automatically activates slow-sync flash, taking the background into account to achieve appropriate automatic flash exposure control.

・ Beware of camera shake and subject blurring
When shooting with slow-sync flash, the slow shutter speed demands use of a tripod to prevent camera shake.
Wireless multiple flash FE lock
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