gPhoto2

How to stream the preview image from a Canon 5D via USB

Webcam image looks noisy and blurry, but you have a top DSLR camera? Stream the preview and use it as an (expensive) webcam:

modprobe v4l2loopback gphoto2 --stdout --capture-movie | gst-launch-1.0 fdsrc fd=0 ! decodebin name=dec ! queue ! videoconvert ! tee ! v4l2sink device=/dev/video0

Source: https://stackoverflow.com/questions/12278688/canon-dslr-video-loop-back-using-v4l2loopback-and-edsdk-liveview