You have the option of setting different shipping zones, so that you can enter a variety of shipping charges for each product depending on where in the world it will ship.
The shipping zones are meant to be fairly broad in scope, on a continental scale rather than by specific countries or states. If you enter too many shipping zones, the product management pages (as well as the shopping cart checkout) will get unwieldy and out of control. It's best to enter between 1 and about 3 or 4 shipping zones at most.
A good selection of shipping zones might be something like: "US, Canada, Europe, Worldwide".
These are fairly broad regions, and it will be impossible to input exact shipping charges; however, at least you can enter ballpark figures which won't leave you in the hole if a customer from South Africa orders a print.
Another easier option is to just have one single shipping zone to keep things simple, then enter a message on the shopping cart page that says something like "International orders will incur additional shipping fees. Please contact me prior to purchase".