This is one solution for taking backup of photos when travelling. There is a good chance most people have the gear (see gear list below) necessary for taking backup all ready. This solution only works using an Android phone (I think?)
In short the backup workflow is as follows.
Copy images from SD-card to mobile phone, using the OTG cable an SD card reader Copy images from mobile phone to external HDD using OTG cable
At this point images are now in three different devices. If your phone has the capacity you could leave them there until get home to your stationary backup at the office. I would definitively recommend leaving images on the SD card(s) if you have enough space.
- Mobile phone (Android)
- OTG USB cable
- SD card reader
- SD card
- External harddrive