Subscribing to image data 8UC3

[dmorris0]

I am playing one of the rosbag files which has an image topic /image_front_left of type 8UC3. In my subscriber callback I am attempting to convert it to bgr8 format with:
img = self.bridge.imgmsg_to_cv2(msg,'bgr8')
I think this makes sense, but I get an error:
[8UC3] is not a color format. but [bgr8] is. The conversion does not make sense
Now I don't think this makes sense, as 8UC3 is a color format.

Am I doing something wrong in subscribing this way? Do you have example code subscribing to the image topic?