What Is Electronic Front-Curtain Shutter (EFCS) Mode?

The Electronic Front-Curtain Shutter (EFCS) is a hybrid exposure mechanism available on many modern DSLR and mirrorless camera bodies (including the Nikon D850, Z6, Z7, and Sony A7 III).

In EFCS mode, the physical opening front curtain does not move at all — exposure begins via an electronic pixel reset across the sensor array. Exposure concludes when the physical rear curtain closes.

3 Key Advantages of EFCS Mode

1. 50% Reduction in Mechanical Shutter Wear: Because the mechanical opening curtain never actuates or resets, wear on mechanical linkages is reduced by half.
2. Elimination of Shutter Shock (Micro-Blur): Eliminating the mechanical impact at the start of exposure delivers ultra-sharp micro-contrast during macro and telephoto photography.
3. Quieter Shutter Operation: Reduced acoustic noise level during quiet indoor events or theatrical performances.

The Hidden Drawback: Truncating Background Bokeh Orbs

When using EFCS at extremely fast shutter speeds (faster than 1/2000 second) with fast prime lenses (f/1.2, f/1.4, f/1.8), a physical optical side effect occurs:

Due to the physical distance gap between the sensor surface and the rear mechanical curtain, out-of-focus bokeh background circles are sliced in half, taking on an asymmetrical "lemon slice" shape.

Shutter Mode Selection Recommendations

Shooting Scenario	Recommended Shutter Mode	Primary Benefit
Landscape, Macro, Studio (1/10 – 1/500 sec)	EFCS (Electronic Front-Curtain)	Zero micro-vibration and reduced curtain wear
Bright Outdoor Portraits at f/1.4 (1/4000 sec)	Fully Mechanical Shutter	Preserves perfectly circular background bokeh
Action Sports, Quiet Venues	Silent (Fully Electronic Shutter)	Silent operation and zero mechanical wear