Lisbon itself will give you plenty of opportunities to take pictures. Especially beautiful is Castelo de São Jorge, the Convento do Carmo in the Bairro Alto, and of course all the tiny roads in the old bairros (quarters) - just to name a few things downtown.
Next I would visit Belém, a beautiful suburb of Lisbon. Here you should visit the Mosteiro dos Jerónimos de Belém (a monastery) and the famous Torre de Belém.
If you rent a car, should definitely visit Sintra. It is located between Lisbon and the Atlantic Ocean, appr. 40 minutes by car.
Sintra was chosen by the royal families as their summer residence and is spectactular because of its subtropical climate and beautiful landscape, probably the nicest place on the Iberian Peninsula. The famous writer Lord Byron called it "Glorious Eden".
When in Sintra, visit the Palacio Nacional (Paco Real), and the Palácio de Pena (looks a bit like the portuguese version of the german Neu-Schwanstein). My favourite place for taking pictures is the Quinta de Monserrate, a small 19. century castle in Moorish style with a fantastic large garden of exotic trees. Also worth visiting is Convento dos Capuchos, a 16th century monastery in a mystical, often foggy cork tree forest (appr. 6 mile outside of Sintra).
For pure landscape the Cabo da Roca (another 40 minutes from Sintra)is worth visiting. It is the western most point of continental Europe with a great view over the rugged coast.
Hope this helps!