There are roughly 23 occasions, 47 pictures total, where there were pictures taken of Nietzsche, alone and in company. Most pictures are from his time as a student and professor in Basel and from when he was sick. A lot of the pictures that you see here you can find on the internet, but I can recommend reading the book: “Habt ihr noch eine photographie von mir” From Hansdieter Erbsmehl. It is written in German and if that is no problem you will find a lot of information about each picture from what he is wearing to information about the letters he has written and wherein he talks about the pictures. Besides reading his own books and a biography this is a good way to place Nietzsche in his time and place.