Impressive! Working as a Gaffer I use it time to time to check the temp on the lamps if any of them looks suspicious. The app really impreses with the accuracy: +/- 200K but that's totally acceptable. Worth every penny if you don't have colormeter on you. Need to have a trained eye though, to recognize a misreading.
Works with a gray card I use this with the X-Rite Color Checker Passport's gray card and it works well enough to set the white balance for my BMPCC that doesn't have a built-in white balance function. Probably depends on the the phone you're using and the accuracy of the phone's camera. I'm using this on a Nexus 6.
You have to know how to use it When using this app, you must take a reading from where the camera is positioned. For instance, if the camera is in a doorway and shooting towards windows, place a white card (or gray card) in front of the lens of the camera and take the reading. One of the biggest problems with ANY colorimeter, are the bulbs being used today. Take average readings of all light in the room, You will get anywhere from about 3000 - 42000 and you must average that out to midway but must also guess at which are the strongest lights. Nothing is perfect these days when shooting indoors but I find this one gets me close and easier to process. Much more reliable than relying on most camera AWB feature. They've NEVER worked for me.
Surprisingly accurate on my devices I tested this application against several known color temperature sources and it reported the color temperature/Kelvin within a very small variance to the expected number. Nexus 5 running stock Android 6.0.0 rooted it was consistently within +/-100K. Nexus 7 (2013) stock Android 6.0.0 rooted it was less accurate varying by +/-200K. Samsung S5 Android 5.1 consistent within +/-200K. Surprise results on Amazon Fire Phone FireOS 4.6.3 rooted varying +/-100K.
Amazing. Simply amazing Comes in handy working as a cinematographer. May not always be 100% dead on, but the preset suggestion is always right so it will give you a starting point when something is wonky. Im suprised there arent more apps thay do this. Worth every penny.
Worth the money I use the Galaxy s. I'm a photographer and through my experience The Calvin readings are exactly right. The only issue I would suggest is no ability to record with flash. Needs some ability to read fash temps. Worth the money!
MONEY BACK GUARANTEE - If you are not happy with the performance of the app on your device, let me know and I give you a full refund! Valid within a whole month from the date of purchase.