Use DSLR Manjaro 20.1

Steps:

1. Install the linux-headers for your Kernel (same as your kernel version)
   sudo pacman -S linux-headers

2. Install gphoto2 and its dependencies (if v4l2 failed to install check step 1.)
   sudo pacman -S gphoto2 v4l-utils v4l2loopback-dkms ffmpeg

3. Add Camera module to the modprobe flags
   sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2

4. Allow DSLR to boot with the system

   sudo nano /etc/modprobe.d/dslr-webcam.conf

   # Module options for Video4Linux, needed for our DSLR Webcam
alias dslr-webcam v4l2loopback
options v4l2loopback exclusive_caps=1 max_buffers=2

5. Try capture
   gphoto2 --capture-image-and-download

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

7. Create script/allow execution of the script - so streaming is easier than remembering a full Linux command -

   nano ~/script/dslr.sh

   #!/bin/bash
echo "Streaming to /dev/video0"
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0 -hwaccel nvdec -c:v mjpeg_cuvid

   chmod 755 ~/script/dslr.sh

Ref: https://www.crackedthecode.co/how-to-use-your-dslr-as-a-webcam-in-linux/