Thanks for your question!
Generally, in Italian we don't use as many possessive adjectives as in English. For instance, in English you would most likely say "Raise your arm!" and not "Raise the arm!". In Italian, on the other hand, you would say "Alza il braccio!" and not "Alza il tuo braccio!". It's implicit that it's "your" arm.
The same goes for the example you shared: "Porto la macchina fotografica" instead of "Porto la mia macchina fotografica". Since I'm bringing it, it's somehow implicit that it's mine. However, please note that saying "Porto la mia macchina fotografica" would be correct too. In that case, you would stress the fact that it's yours, and not someone else's.
Let me know if you have any other questions!