Manual focus gets unstable sporadically

Masaki

We are using ctrl.setManualFocus() as shown in the attached script. We call it at the start of our application and expect the OAK-D to maintain a constant focus position while capturing images. However, we've noticed that the camera lens occasionally moves (trying to AF ?), causing some images to become blurry. Is there any way to verify that the manual focus remains active at all times?

Hardware: OAK-D Pro AF
OAK-D firmware version: 3.9.9.
Depthai version: 2.22.0.0
PC environment: Ubuntu 18.04, ROS1 Melodic
Target object distance (WD): ~40 cm

def focus_callback(msg):
    global startX, startY, width, height
    startX = int(msg.pose.pose.orientation.x)
    startY = int(msg.pose.pose.orientation.y)
    width = int(msg.pose.pose.orientation.z)
    height = int(msg.pose.pose.orientation.w)
    ctrl = dai.CameraControl()
    # time.sleep(1) # Wait for camera switching
    exposureTimeUs = msg.pose.pose.position.x
    lensDistance = msg.pose.pose.position.y
    iso = msg.pose.pose.position.z
    ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.OFF)
    if lensDistance != 0:
        ctrl.setManualFocus(int(lensDistance))
    elif lensDistance == 0:
        ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.AUTO)
    if exposureTimeUs != 0:
        if iso == 0:
            iso = 100
        ctrl.setManualExposure(int(exposureTimeUs), int(iso)) #ISO 100..1600
    elif exposureTimeUs == 0:
        ctrl.setAutoExposureEnable()
    # qControl.send(ctrl.setAutoFocusRegion(startX,startY,width,height))
    # time.sleep(3) #Wait for focus on the barcode
    rospy.logwarn('focus_callback service call is finished BUT focus may take 3 more seconds')
    return(True)

jakaskerl

Masaki
You can track the lens position of of each frame.
luxonis/depthai-pythonblob/main/examples/ColorCamera/rgb_camera_control.py#L139

Thanks,
Jaka

Masaki

Thanks for your response, Jaka. I'm going to check ispFrame.getLensPosition() first to see if there's any hidden lens focusing command.

If the lens position is constant, is there any chance the lens could still move by itself while taking images?

jakaskerl

Masaki
No. It shouldn't. But if you were to hit the device, the lens will move. Not sure if the change in position will be tracked.

Thanks,
Jaka

Masaki

Thanks for your support. We have finally solved the problem; the manual focus command was not being correctly sent.

After changing the code to use the qControl.send() function, the camera now goes into manual focus mode and there is no sporadic focus movement.
```

def focus_callback(msg):
    global startX, startY, width, height
    startX = int(msg.pose.pose.orientation.x)
    startY = int(msg.pose.pose.orientation.y)
    width = int(msg.pose.pose.orientation.z)
    height = int(msg.pose.pose.orientation.w)
    ctrl = dai.CameraControl()
    # time.sleep(1) # Wait for camera switching
    exposureTimeUs = msg.pose.pose.position.x
    lensDistance = msg.pose.pose.position.y
    iso = msg.pose.pose.position.z
    qControl.send(ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.OFF))
    if lensDistance != 0:
        qControl.send(ctrl.setManualFocus(int(lensDistance)))
        qControl.send(ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.OFF))
    elif lensDistance == 0:
        qControl.send(ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.AUTO))
        print("Auto focus mode is set")
    if exposureTimeUs != 0:
        if iso == 0:
            iso = 100
        qControl.send(ctrl.setManualExposure(int(exposureTimeUs), int(iso))) #ISO 100..1600
        qControl.send(ctrl.setAutoFocusMode(dai.RawCameraControl.AutoFocusMode.OFF))
    elif exposureTimeUs == 0:
        qControl.send(ctrl.setAutoExposureEnable())
        print("Auto exposure mode is set")
    # qControl.send(ctrl.setAutoFocusRegion(startX,startY,width,height))
    # time.sleep(3) #Wait for focus on the barcode
    rospy.logwarn('focus_callback service call is finished BUT focus may take 3 more seconds')
    return(True)