diff --git a/README.md b/README.md
index ee5701d..ec5e655 100644
--- a/README.md
+++ b/README.md
@@ -109,6 +109,12 @@ Test the camera on its own (uses the device from `config.toml`):
 python3 camera.py
 ```
 
+It first prints a pre-flight dump of every camera the system sees
+(`/dev/v4l/by-id/` names, device nodes, and what each node identifies as),
+then reports which device was matched, resolved, and opened, plus the OpenCV
+version. If the booth ever uses the wrong camera, run this and read the
+output — it shows exactly where the selection went sideways.
+
 **If it reports black frames** (or the live preview shows a warning): the
 Macally cam's chipset sometimes wedges and streams pure black until it is
 power-cycled. **Unplug the camera, plug it back in, and restart the
diff --git a/camera.py b/camera.py
index 43de183..271fc88 100644
--- a/camera.py
+++ b/camera.py
@@ -14,6 +14,16 @@ import cv2
 import numpy as np
 
 
+def sysfs_name(device_path):
+    """Human-readable name of a /dev/videoN node from sysfs, e.g.
+    'Macally USB2.0Camera: Macally U'. Empty string if unknown."""
+    try:
+        with open(f"/sys/class/video4linux/{os.path.basename(device_path)}/name") as f:
+            return f.read().strip()
+    except OSError:
+        return ""
+
+
 def resolve_device(setting, wait_seconds=15):
     """Turn the config's camera device setting into something cv2 accepts.
 
@@ -33,16 +43,34 @@ def resolve_device(setting, wait_seconds=15):
         needle = setting[len("auto-"):].lower()
         deadline = time.monotonic() + wait_seconds
         waited = False
+        last_seen = None
         while True:
             candidates = sorted(glob.glob("/dev/v4l/by-id/*-video-index0"))
+            # Re-print the scan only when the device set changes, so a slow
+            # USB camera showing up mid-wait doesn't spam the log.
+            if candidates != last_seen:
+                last_seen = candidates
+                if candidates:
+                    print(f"Scanning /dev/v4l/by-id for '{needle}':")
+                    for path in candidates:
+                        print(f"  {os.path.basename(path)} -> "
+                              f"{os.path.realpath(path)}")
+                else:
+                    print("Scanning /dev/v4l/by-id: no cameras found yet.")
             for path in candidates:
                 if needle in os.path.basename(path).lower():
-                    return os.path.realpath(path)
+                    device = os.path.realpath(path)
+                    print(f"Matched '{needle}': "
+                          f"{os.path.basename(path)} -> {device}")
+                    return device
             if time.monotonic() > deadline:
-                names = [os.path.basename(p) for p in candidates]
+                all_entries = [
+                    f"{os.path.basename(p)} -> {os.path.realpath(p)}"
+                    for p in sorted(glob.glob("/dev/v4l/by-id/*"))
+                ]
                 raise RuntimeError(
                     f"No camera matching '{needle}' found. "
-                    f"Available cameras: {names or 'none'}"
+                    f"Available cameras: {all_entries or 'none'}"
                 )
             if not waited:
                 waited = True
@@ -68,6 +96,12 @@ def crop_4x3(frame):
 class Camera:
     def __init__(self, device_setting, width, height):
         device = resolve_device(device_setting)
+        dev_path = device if isinstance(device, str) else f"/dev/video{device}"
+        name = sysfs_name(dev_path)
+        print(f"Camera: setting={device_setting!r} resolved={dev_path!r} "
+              f"cv2={cv2.__version__}")
+        if name:
+            print(f"Camera: {dev_path} identifies as '{name}' (sysfs)")
         self.cap = cv2.VideoCapture(device, cv2.CAP_V4L2)
         if not self.cap.isOpened():
             raise RuntimeError(f"Could not open camera {device!r}")
@@ -75,6 +109,9 @@ class Camera:
         self.cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc(*"MJPG"))
         self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
         self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+        actual_w = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
+        actual_h = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
+        print(f"Camera: opened {dev_path}, negotiated {actual_w}x{actual_h}")
 
         self._lock = threading.Lock()
         self._frame = None
@@ -140,6 +177,22 @@ if __name__ == "__main__":
     import tomllib
     from pathlib import Path
 
+    print("== Camera pre-flight ==")
+    print(f"OpenCV version: {cv2.__version__}")
+    by_id = sorted(glob.glob("/dev/v4l/by-id/*"))
+    if by_id:
+        print("/dev/v4l/by-id entries:")
+        for p in by_id:
+            print(f"  {os.path.basename(p)} -> {os.path.realpath(p)}")
+    else:
+        print("/dev/v4l/by-id: (empty or missing)")
+    nodes = sorted(glob.glob("/dev/video*"))
+    if nodes:
+        print("Video device nodes:")
+        for n in nodes:
+            print(f"  {n}  {sysfs_name(n)}")
+    print("=======================")
+
     if len(sys.argv) > 1:
         device = sys.argv[1]
     else: