How would I start a 60 minute discussion on the usefulness of "Photographs as a visual text"?What are the major benifits of "Photograph as a visual text"?
I just responded to your other question with some general ideas for how to start and generate discussions. The same principles apply here, especially with your idea of how long the discussion can go on for. Discussions are very tricky to run properly and successfully and I would say that 60 minutes is far too long. You should be aiming for 15 at the most in my opinion.
Given the topic, if I were you I would start the discussion by looking at a series of famous photos that are recognised as being good examples of visual text - you probably know more about this than me, so I am sure you can think of examples. Maybe the picture of the vietnamese girl running from the napalm bombing might be one you could choose. You could use these photos to discuss why they are effective forms of visual text and how we "read" them. This would provide an excellent starter for you to be able to go on and ask the bigger question of whether photographs as a medium make for good visual texts. It is imperative that you give the participants space and time to consider the question before the discussion begins. Also make sure you set a definite end time on the discussion.
Hope this helps and good luck!