If you want to say more naturally in English, I would say: A: Have you seen my camera? B: No, I haven't. But "気がつく" means "notice". So if you want to translate it directly, it can be: A: Isn't there a camera here? B: Well, I didn't notice it... Is that a enough answer for your question? If it's not, please leave a comment.

正确的意思是＂我没注意到[意识到]（所以不知道）＂。其实意味着＂我不知道＂，说得有些委婉。