rtspbuffercam can be used to connect to and read images for rtsp enabled camera's.

It uses sub processes to exhaust camera's buffer and eliminate any lag that might occur using a vanilla opencv connection.

Using pypi

pip install rtspbuffercam

or from source

git clone https://github.com/lewis-morris/rtspbuffercam
cd rtspbuffercam
python setup.py install

#import the rtspcam
from rtspcam import Camera

#create a new rtspcam object  
cam = Camera("rtsp:https://admin:[your password]@192.168.0.40/h264Preview_01_main")

#read image
image = cam.get_frame()