Go into your camera on your device and you wilk see an icon marked settings, scroll down until you see storage click on storage and there you will have the option of where to save your photos, and hope this info was helpful.
To be honest I do not know. Once you've taken pics and they are saved on the tablet I don't think they can be moved to the ext sd card. But once you install a card then you can save all other pics to it by changing the storage options in the settings menu. Hope this helps.
I assume you're interested in how to move existing photos, not setting up your default for future photos. The only way I have found to do this is to select your photo in the Gallery. Move it to DropBox. In DropBox, on the far right is a downward arrow. When you touch that you will get an option to Export. Once you select Export, it will give you options on where to export it to and select the external SD card.