not a high key portrait challenge
It really is. He keeps coming up with challenges that require actual knowledge of photographic techniques and terminology! Doesn't he know that photography for many dpr members isn't about knowing actual technique? It's about having the best camera and harrumphing all about high ISO noise and DR!
After all, not that many people really buy dslrs to learn about photography and develop the technical chops to produce professional quality images. You just need to be the right camera...
Some people operate cameras. Others use them to create images. There is a difference.