diff --git a/libraries/AP_Camera/AP_Camera.cpp b/libraries/AP_Camera/AP_Camera.cpp
index 06a903d2828..1cf63db609a 100644
--- a/libraries/AP_Camera/AP_Camera.cpp
+++ b/libraries/AP_Camera/AP_Camera.cpp
@@ -70,17 +70,6 @@ AP_Camera::AP_Camera(uint32_t _log_camera_bit) :
     _singleton = this;
 }
 
-// set camera trigger distance in a mission
-void AP_Camera::set_trigger_distance(float distance_m)
-{
-    WITH_SEMAPHORE(_rsem);
-
-    if (primary == nullptr) {
-        return;
-    }
-    primary->set_trigger_distance(distance_m);
-}
-
 // momentary switch to change camera between picture and video modes
 void AP_Camera::cam_mode_toggle()
 {
@@ -308,6 +297,62 @@ void AP_Camera::handle_message(mavlink_channel_t chan, const mavlink_message_t &
     }
 }
 
+#if HAL_MAVLINK_BINDINGS_ENABLED
+// a method which handles mavlink-style semantics for instance_id; if
+// instance_id is zero or matches backend instance ID code is run
+MAV_RESULT AP_Camera::handle_mav_DO_SET_CAM_TRIGG_DISTANCE(uint8_t instance_id, bool trigger, float dist_m)
+{
+    for (uint8_t i=0; i<AP_CAMERA_MAX_INSTANCES; i++) {
+        if (_backends[i] == nullptr) {
+            continue;
+        }
+        // honour packet instance number:
+        if (instance_id != 0 && i+1 != instance_id) {
+            continue;
+        }
+        _backends[i]->set_trigger_distance(dist_m);
+        if (trigger) {
+            _backends[i]->take_picture();
+        }
+    }
+
+    return MAV_RESULT_ACCEPTED;
+}
+
+MAV_RESULT AP_Camera::handle_mav_SET_CAMERA_ZOOM(uint8_t instance_id, CAMERA_ZOOM_TYPE mav_zoom_type, float zoom_value)
+{
+    ZoomType zoom_type;
+    switch (mav_zoom_type) {
+    case ZOOM_TYPE_CONTINUOUS:
+        zoom_type = ZoomType::RATE;
+        break;
+    case ZOOM_TYPE_RANGE:
+        zoom_type = ZoomType::PCT;
+        break;
+    default:
+        // invalid param1
+        return MAV_RESULT_DENIED;
+    }
+
+    MAV_RESULT result = MAV_RESULT_ACCEPTED;
+    for (uint8_t i=0; i<AP_CAMERA_MAX_INSTANCES; i++) {
+        if (_backends[i] == nullptr) {
+            continue;
+        }
+        // honour packet instance number:
+        if (instance_id != 0 && i+1 != instance_id) {
+            continue;
+        }
+        // all backends must succeed:
+        if (!_backends[i]->set_zoom(zoom_type, zoom_value)) {
+            result = MAV_RESULT_FAILED;
+        }
+    }
+
+    return result;
+}
+#endif  // HAL_MAVLINK_BINDINGS_ENABLED
+
 // handle command_long mavlink messages
 MAV_RESULT AP_Camera::handle_command(const mavlink_command_int_t &packet)
 {
@@ -319,21 +364,17 @@ MAV_RESULT AP_Camera::handle_command(const mavlink_command_int_t &packet)
         control(packet.param1, packet.param2, packet.param3, packet.param4, packet.x, packet.y);
         return MAV_RESULT_ACCEPTED;
     case MAV_CMD_DO_SET_CAM_TRIGG_DIST:
-        set_trigger_distance(packet.param1);
-        if (is_equal(packet.param3, 1.0f)) {
-            take_picture();
-        }
-        return MAV_RESULT_ACCEPTED;
+        return handle_mav_DO_SET_CAM_TRIGG_DISTANCE(
+            packet.param4,                  // instance
+            is_equal(packet.param3, 1.0f),  // trigger
+            packet.param1                   // distance
+        );
     case MAV_CMD_SET_CAMERA_ZOOM:
-        if (is_equal(packet.param1, (float)ZOOM_TYPE_CONTINUOUS) &&
-            set_zoom(ZoomType::RATE, packet.param2)) {
-            return MAV_RESULT_ACCEPTED;
-        }
-        if (is_equal(packet.param1, (float)ZOOM_TYPE_RANGE) &&
-            set_zoom(ZoomType::PCT, packet.param2)) {
-            return MAV_RESULT_ACCEPTED;
-        }
-        return MAV_RESULT_UNSUPPORTED;
+        return handle_mav_SET_CAMERA_ZOOM(
+            packet.param3,                   // instance
+            CAMERA_ZOOM_TYPE(packet.param1), // zoom type
+            packet.param2                    // zoom level
+        );
     case MAV_CMD_SET_CAMERA_FOCUS:
         // accept any of the auto focus types
         switch ((SET_FOCUS_TYPE)packet.param1) {
diff --git a/libraries/AP_Camera/AP_Camera.h b/libraries/AP_Camera/AP_Camera.h
index 2a724fffb8d..f974d8ac39f 100644
--- a/libraries/AP_Camera/AP_Camera.h
+++ b/libraries/AP_Camera/AP_Camera.h
@@ -86,6 +86,7 @@ public:
     // update - to be called periodically at 50Hz
     void update();
 
+#if HAL_GCS_ENABLED
     // handle MAVLink messages from the camera
     void handle_message(mavlink_channel_t chan, const mavlink_message_t &msg);
 
@@ -98,6 +99,13 @@ public:
 
     // send camera information for a specific instance (0-based) to GCS
     void send_camera_information(uint8_t instance, mavlink_channel_t chan);
+#endif  // HAL_GCS_ENABLED
+
+#if HAL_MAVLINK_BINDINGS_ENABLED
+    // methods to handle mavlink-style instance-id (0 meaning all cameras)
+    MAV_RESULT handle_mav_DO_SET_CAM_TRIGG_DISTANCE(uint8_t instance_id, bool trigger, float dist_m);
+    MAV_RESULT handle_mav_SET_CAMERA_ZOOM(uint8_t instance_id, CAMERA_ZOOM_TYPE mav_zoom_type, float zoom_value);
+#endif  // HAL_MAVLINK_BINDINGS_ENABLED
 
     // select which instance to send on the next deferred MSG_CAMERA_INFORMATION send
     void set_camera_information_send_instance(int16_t instance) { _camera_information_send_instance = instance; }
@@ -111,7 +119,6 @@ public:
     void control(uint8_t instance, float session, float zoom_pos, float zoom_step, float focus_lock, int32_t shooting_cmd, int32_t cmd_id);
 
     // set camera trigger distance in a mission
-    void set_trigger_distance(float distance_m);
     void set_trigger_distance(uint8_t instance, float distance_m);
 
     // momentary switch to change camera between picture and video modes