There is a difference in English between few and a few.
The tourist is taking few pictures. The number of the pictures is definitely small.
The tourist is taking a few pictures. It is similar to: taking some pictures. In Hungarian: A turista fényképez egy keveset. / A turista fényképez néhányat.
It wouldn't be natural to say just "few" I think "a few" should definitely be accepted as well just for the sake of correct English
I do get the point of the opinions before because, i figure, in Hungarian keveset means "few" (not a lot) and a few does not convey this nuance but still would it not be proper usage of the English language
I think this is a quirk in this particular method of learning: understanding nuances of emphasis and subtle changes in grammatical structures. It seems as if learning a natural way of speaking is not really emphasised. Another way that an English speaker might commonly say this phrase is: the tourist is taking very few pictures.