Carry this little lollipop-shaped device with you, and you’ll always have the ability to turn your iPhone into a photographic light meter. It has a CNC milled high-grade aluminum housing, so it will last for years. Inside is a hemispherical diffuser, cardioid-type silicon photo diode light receptor element that measures the range of 0.15 – 250,000 lux ambient light. It doesn’t need batteries, because it draws from the phone’s battery. Three apps are available for best performance for photo, video, or pinhole cameras. Lumu is available in black or silver; each comes with a leather case and a necklace to keep the Lumu around your neck. Lumu is $149.00 from Lumulabs.