Magic Lantern Firmware Wiki

Focus control[]




Focus screen

Focus menu

Manually set the focus to the desired position and zero the focus counter by selecting "Focus A" (the counter will reset to zero). Then set the focus direction and hold the "Zoom in" button. Focus using follow-focus, until the desired second focus position is selected. If you overshoot, change the direction and use "Zoom in" to reverse direction. Due to bug 71 the "Zoom out" button can not be used.

On the 550D, use "Zoom out". Due to a similar bug, the "Zoom in" button can not be used.

Once the new focus position is selected, select "Rack focus" to switch between the two.


Step size is signed 16-bit value. Positive is focusing further away, negative is focusing closer. Larger values are more change.

#define PROP_LV_FOCUS      0x80050001 
#define PROP_LV_FOCUS_DONE 0x80050002 
struct prop_focus 
        uint8_t                 active;         // off_0x00, must be 1 
        uint8_t                 step_hi;        // off_0x01 
        uint8_t                 step_lo;        // off_0x02 
        uint8_t                 mode;           // off_0x03 unknown, usually 7? 
} __attribute__((packed)); 
SIZE_CHECK_STRUCT( prop_focus, 4 );