"The smartphone accessory that makes you a better film photographer."
From The Verge Lumu review:
“I took the Lumu and my camera outside this past weekend to take pictures of my family at the park. The lighting conditions were fairly difficult: the sun kept ducking behind the clouds and then reappearing, requiring me to adjust exposure settings on my camera for nearly every shot. The Lumu’s instant readings gave me accurate recommendations, whether my daughter was playing in bright sunlight or sitting in the shade.”