You might think the difference in setups that create high key and low key lighting is significant, but on the other hand, just a slight change in modifiers and light position can make a huge difference. This excellent video tutorial will show you how to create both high key and low key portraits using two strobes with almost identical modifiers.
Coming to you from Lindsay Adler Photography, this fantastic tutorial will show you how to create separate high key and low key portraits using just two strobes and the same modifiers. Surprisingly, the only difference between the shots is that in one, Adler uses a reflector, while in another, she adds a grid and changes the position of the key light. I think this is an especially important lesson, as it shows how having a strong grasp of your lighting is crucial, not only to get the exact shot you want, but also because understanding how seemingly minute changes can make a drastic difference in the final look of your image will help you to know the full range of creative possibilities available to you at any given time. Check out the video above for the full rundown from Adler.