Every photographer and video pro knows the importance of investing in decent lights, light meters, and other useful tools. The Lumu Power Light, Flash, and Color Meter is developed for iphotographers. It attaches to iPhones running iOS 8.0 or later through the Lightning port and can measure flash exposure, color temperature, and illuminance.
The device can measure light in a range of 0.15-250,000 lux and color temperature from 1500-20,000K. Its free app displays color and light information on your screen, so you can adjust your shots. No batteries are needed either. Sets you back under $250 at this time.[where to find it]