gphoto2 how to handle Out of Focus warning

Here is how I capture image with my camera

import logging
import gphoto2 as gp
def main():
    def callback(level, domain, string, data=None):
        print('Callback: level =', level, ', domain =', domain, ', string =', string)
        if data:
            print('Callback data:', data)

    logging.basicConfig(
        format='%(levelname)s: %(name)s: %(message)s', level=logging.WARNING)
    callback_obj = gp.check_result(gp.use_python_logging())

    camera = gp.Camera()
    camera.init()
    try:
        camera_file_path = gp.check_result(camera.capture(gp.GP_CAPTURE_IMAGE))
    except gp.GPhoto2Error as ex:
        print("callback: ", ex, ex.code, ex.message, ex.string)
    camera.exit()

if __name__ == "__main__" : exit(main())

If the camera is not able to focus it generates following error

...
WARNING: gphoto2: (ptp_usb_getresp [usb.c:466]) PTP_OC 0x90c8 receiving resp failed: Out of Focus (0xa002)
WARNING: gphoto2: (camera_nikon_capture [library.c:3153]) 'ret' failed: 'Out of Focus' (0xa002)
WARNING: gphoto2: (gp_context_error) Out of Focus
WARNING: gphoto2: (gp_camera_capture [gphoto2-camera.c:1340]) 'camera->functions->capture (camera, type, path, context)' failed: -1
('callback: ', GPhoto2Error('[-1] Unspecified error',), -1, '[-1] Unspecified error', 'Unspecified error')

The exception error code is -1 but how can I capture Out of Focus warning?

UPDATE

Filtered out unnecessary errors from logs

import logging
import gphoto2 as gp
from datetime import datetime
def main():
    def callback(level, domain, string, data=None):
        err_codes = ("(0x2005)", "(0x2019)")
        if not string.decode().endswith(err_codes):
            print("[{0}] {1}: {2}".format(datetime.utcnow(), domain.decode(), string.decode()))
        if data:
            print('Callback data:', data)

    callback_obj = gp.check_result(gp.gp_log_add_func(gp.GP_LOG_ERROR, callback))
    camera = gp.Camera()
    try:
        camera.init()
    except gp.GPhoto2Error as err:
        exit(err.code)

    try:
        camera_file_path = camera.capture(gp.GP_CAPTURE_IMAGE)
    except gp.GPhoto2Error as err:
        exit(err.code)
    camera.exit()

if __name__ == "__main__" : exit(main())

You've defined a callback function, in which you could parse the error string to detect out of focus, but you haven't installed your callback so libgphoto2 isn't using it. Use gp_log_add_func to install your callback.

Also, you're passing the return value of camera.capture to gp.check_result. This is incorrect as camera.capture already checks the result and raises an exception if there's an error.