I've used it, its fairly accurate but doesn't seem 100%. If I had a lightmeter I could compare. The one I Use, I'll have to find out the company. I'd say its within 2 stops or so for the one I use. It tends to read higher.
i do not have a lightmeter, so I cannot compare for the absolute measurement.
however they seem to give quite consitent results when repeating the same measurment, so it is possible that you can use them to measure the *relative* difference between two lights ... does it make sense?
I tried 2 or 3 on my Galaxy Slll out of boredom. One that was available for my phone and my sisters iPhone 5, gave identical results between our phones on the same subject. They were consistently less than a half stop off either way. I deleted it because I had no intention of using it over my L-358.
I use similar ones on Android.
They are using the camera on the phone facing you, so it's easy to read the screen.
I did not notice anything more than 1/3 stops deviation compared to camera meter, so it's not that bad on continuous light.
Robb Mann wrote: Is it better on some iphone versions? I lnow awb got a lot better on the iphone 4s vs the 3gs.
Tried it on a 4 and it was random as hell.
In very specific, flat lit circumstances (like outdoors on a cloudy day pointing at something neutral colored) they're okay (+/- 1 stop) as a reflective meter .
But as soon as you try and use it as an incident meter with any kind of contrast in the scene (which let's face it, is the only reason for using a handheld meter over TTL) then they're totally rubbish.
A fun gimmick to try out though, but totally impractical imo (much like 99% of iPhone apps )