Python opencv cv2.VideoCapture freeze

My code always freezes on me. I'm testing it on this code.

import cv2

cap = cv2.VideoCapture('/dev/video0') # frozen
ret, frame = cap.read()
print(ret, frame)

My configuration is

• raspberry pi

• Python 3.9.2

• Canon 600D

this command works normally

gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

There may be a bug in the Cannon 600D.

it needed to run

sudo modprobe v4l2loopback

and

gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

and gphoto2 run