Is there a way to connect an external camera, like DSLR to jetson nano?
What is your desired application?
In general, it certainly should be possible. But it might be a bit of work – and it will depend heavily on the camera. Some DSLRs might work as a webcam via an onboard USB connector and LiveView. Others might need a software interface. You might start your search with your camera type and “Ubuntu”. If you can find a tutorial for your camera, and somebody else has described using it as a webcam, you’ll be in good shape. If you can’t, you might not be able to use the DSLR and the included examples and utilities as is – they might require modification, or capturing and transferring from the camera before processing.
I used an old Canon camera which has USB. I have not used this in a very long time, but digikam was able to work with the camera, so you might give that a try if your DSLR camera has USB.
I used a Raspberry Pi during the last solar eclipse to capture a sequence from a slr. I used darktable to set up the capture (lightroom clone) which uses gphoto2 as a backend. (see link for supported cameras and features)
Ironically, I have a Lightroom license, but Lightroom didn’t support support my dlsr for tethered capture at the time, while gphoto2 did. Gphoto rocks.
Are you interested in tethered photo capture (eg, at regular intervals) or a live video stream?
You can probably connect any camera via USB if USB provision is there with camera. Follow the steps mentioned here: http://www.linuxintro.org/wiki/Set_up_a_Webcam_with_Linux
I tried with an unlisted camera & became successful.
Note that WiFi connection could be required.