I have 2 Pi Zero Ws (wifi), each with a Pi camera connected to them. Both Pis/cams are running on battery power and deployed in the desert. There is no network or internet connection. The cams are programmed to take 4 still images every second (1 every 250ms).
There are two things I'm concerned with and need help. The first is that both Pis/cams should share a common time reference. The second, which obviously builds on the first, is that the images from each pi/cam should ideally be synchronized.
The duration of the deployment will obviously be bound by battery power, but I'd like pursue the best option for sharing a common reference time and synchronizing the images.
EDIT: Yes, my question does not show any code or present an code error, because I have not attempted any solution. I'm trying to get advice on where to focus further research efforts and why you believe the method will work best. I'm not an expert with Linux systems or the Raspberry Pi, so please give me enough information to push me in the right direction. I'm not asking for code or you to do my work, I'm asking for you to guide me in choosing the proper solution given my situation.