Custom Variable 1

Using Half-Press Duration for Autofocus (C Var 1)

C Var 1 controls the length of the half-press (HP) signal that is sent to the camera before the full-press (FP) trigger. By extending this half-press duration, the sensor gives the camera time to perform autofocus functions before the image is taken.

With newer mirrorless cameras offering highly advanced autofocus systems — including animal-eye detection — this feature allows autofocus to be used in camera-trap setups for the first time.

When the half-press signal is active, the camera can detect and focus on the subject before the shutter is triggered, enabling the possibility of shooting with a shallow depth of field and precise eye focus, creating images that differ greatly from traditional manual-focus camera-trap photos.

Practical Considerations

• Focus reliability: Autofocus-based setups are inherently less reliable than manual focus. Some images may be misfocused if the camera fails to detect the correct point of interest or locks onto background elements.
• Lighting: Autofocus requires continuous light to function. For nighttime use, video lights may be necessary, as flashes alone will not provide light until after focus is attempted.
• Timing: The optimal half-press duration depends on the camera model and lens. Mirrorless cameras typically require between 0.2 s and 1 s for accurate subject detection and focus acquisition.

This setting introduces a new creative approach to camera trapping — enabling autofocus precision and shallow-depth-of-field imagery previously impractical with PIR triggers. While manual focus remains the most dependable method for critical work, C Var 1 offers an exciting opportunity to experiment with modern autofocus systems for more dynamic and cinematic results.