diff --git a/backend/api/webhooks.py b/backend/api/webhooks.py
index f67087a..774b8ed 100644
--- a/backend/api/webhooks.py
+++ b/backend/api/webhooks.py
@@ -8,8 +8,6 @@ from fastapi import APIRouter, Request, Query
 logger = logging.getLogger(__name__)
 router = APIRouter()
 
-DEFAULT_COUNTDOWN = 5.0
-
 
 @router.get("/webhook/photobooth")
 async def photobooth_webhook(
@@ -20,19 +18,36 @@ async def photobooth_webhook(
     led = request.app.state.led_service
     btn = request.app.state.button_service
     ws = request.app.state.ws_manager
+    cfg = request.app.state.config.leds
 
     logger.info("Webhook photobooth: event=%s type=%s", event_key, mediaitem_type)
     await ws.broadcast({"type": "photobooth_event", "event": event_key, "media_type": mediaitem_type})
 
     match event_key:
         case "counting":
-            led.play("countdown", countdown_duration=DEFAULT_COUNTDOWN)
-            if request.app.state.config.leds.auto_brightness:
+            led.play("countdown", countdown_duration=cfg.countdown_duration)
+
+            # Annuler le pre-flash précédent si toujours en attente
+            prev = getattr(request.app.state, "pre_flash_task", None)
+            if prev and not prev.done():
+                prev.cancel()
+
+            # Déclencher le flash X secondes avant la fin du countdown
+            delay = max(0.0, cfg.countdown_duration - cfg.pre_flash_advance)
+            task = asyncio.create_task(_delayed_flash(led, delay))
+            request.app.state.pre_flash_task = task
+            logger.info(
+                "Pre-flash schedulé dans %.2fs (countdown=%.1fs advance=%.1fs)",
+                delay, cfg.countdown_duration, cfg.pre_flash_advance,
+            )
+
+            if cfg.auto_brightness:
                 pb = request.app.state.photobooth_service
                 asyncio.create_task(_analyze_ambient_lux(led, pb))
 
         case "capture":
-            led.play("capture")
+            # Flash déjà lancé par le pre-flash depuis counting ; ne pas redémarrer
+            logger.debug("Event capture recu (pre-flash déjà actif)")
 
         case "captured":
             led.play("captured")
@@ -57,6 +72,14 @@ async def photobooth_webhook(
     return {"ok": True, "event": event_key}
 
 
+async def _delayed_flash(led, delay: float):
+    """Attend `delay` secondes puis déclenche l'effet flash."""
+    if delay > 0:
+        await asyncio.sleep(delay)
+    led.play("capture")
+    logger.info("Pre-flash déclenché (délai=%.2fs)", delay)
+
+
 async def _delayed_relay_on(btn, delay: float):
     await asyncio.sleep(delay)
     if btn:
diff --git a/backend/services/config_service.py b/backend/services/config_service.py
index 404a367..2cd5ba1 100644
--- a/backend/services/config_service.py
+++ b/backend/services/config_service.py
@@ -64,6 +64,8 @@ class LEDConfig:
     dma: int = 10
     strip_type: str = "WS2812"
     effects: dict = field(default_factory=dict)
+    countdown_duration: float = 3.0   # Durée du countdown photobooth-app (secondes)
+    pre_flash_advance: float = 0.5    # Démarrer le flash X sec avant la fin du countdown
 
     def get_effect(self, name: str) -> LEDEffectConfig:
         raw = self.effects.get(name, {})
@@ -151,6 +153,8 @@ class ConfigService:
                 dma=led_raw.get("dma", 10),
                 strip_type=led_raw.get("strip_type", "WS2812"),
                 effects=led_raw.get("effects", {}),
+                countdown_duration=led_raw.get("countdown_duration", 3.0),
+                pre_flash_advance=led_raw.get("pre_flash_advance", 0.5),
             )
 
         if "print" in raw:
diff --git a/config/settings.yaml b/config/settings.yaml
index 16fb8a1..2cb714d 100644
--- a/config/settings.yaml
+++ b/config/settings.yaml
@@ -39,6 +39,7 @@ leds:
   auto_brightness: true
   brightness: 20
   count: 35
+  countdown_duration: 3.0   # Durée du countdown photobooth-app (secondes)
   dma: 10
   effects:
     capture:
@@ -46,7 +47,7 @@ leds:
       - 255
       - 200
       - 80
-      flash_duration: 2.0
+      flash_duration: 1.0
       flashes: 1
       mode: flash
     captured:
@@ -97,6 +98,7 @@ leds:
       speed: 0.05
   freq_hz: 800000
   pin: 18
+  pre_flash_advance: 0.5    # Démarrer le flash X secondes avant la fin du countdown
   strip_type: WS2812
 photobooth:
   config_file: /home/pi/photobooth-data/config/config.json