best system i have used is to charge a leisure battery with the pv and use an in car charger for the device
im not sure how much energy a tablet needs but a lappy would need a big pv to keep it fed ,my lappy can drain an 85 ahr battery in about 10 hrs via an inverter .
a direct system giving the required input voltage would be more efficient but getting the right input(19v for mine )will take a bit of faffing about. a 24 v lorry battery (or paired leisures )and a shunt to drop the voltage a bit might work quite well
a camera is fairly low energy and recharging little batteries is easy from a big 12v. a mobile will charge in 30 mins via a car charger from a full 12v battery but i dont know how much energy either of those take ,it has always seemed a minor load on the system when i have done off grid .
sorry to be practical rather than technical but the above is based on doing it