I'm preparing a photo essay on a Power Point presentation. I'd like to keep the presentation to around 20 minutes. I'm afraid much longer and I'll start losing the audience. My presentation is getting quite long. I'm to the point where I'm going to have to shorten the presentation or shorten the view time for each slide.
How long do you think is needed to view a photo slide? At what point do you start wishing the presenter would move to the next?