Light meter app
Anybody try an Android/iPhone light meter app to measure your lights luminance?
I'm gonna try out the two most popular light meter apps on Android Play to do some measurements.
beeCam Light Meter
Okay, here are some measurements I just made:
beeCam Light Meter
Room ambient light: 4 lux
Flashlight 1 meter away: 1063 lux
Room ambient light: 5 lux
Flashlight 1 meter away: 1450 lux
Flashlight is a china made 500mW Small Sun Cree flashlight using one 18650 battery.
Most of the light meter apps are OK for photography but have disclaimers about using them for light level readings. I have not looked at any Android ones, but the iOS stuff I've been tempted to try all had statements about accuracy in the fine print. Basically, they don't want you to take a reading on a staircase where someone might faceplant and call a lawyer. However, if you set up a comparison under strict conditions, it will probably work like a bathroom scale: it may not match other scales but it will be consistent to itself.
Basically, the camera in the phone and a 'real' light meter are totally different animals, so don't expect different phones or apps to give you the same readings as a dedicated meter or each other.
Not really concerned about accuracy since I just wanted to have a gauge of how bright everyone's bike light set ups are using these apps instead of basing it on pictures or videos.
By the way, I made some measurements again last night outside the house where there was really minimal light available.
Ambient light: 2 lux
Bike light 2 bike lengths away: 180 lux (flood)
Bike light 2 bike lengths away: 1,200 lux (focused)
It's very likely you'll just swamp out the ability of the sensor to measure light. It's not meant for the intensity of the lights that are in play here.
What about all the light that doesn't hit the sensor? It's totally unreliable for measuring the output of various lights/patterns.....Pretty sure that's why they use a sphere to capture all the light that's being outputted for a proper measurement.
"Light scattered by the interior of the integrating sphere is evenly distributed over all angles. The integrating sphere is used in optical measurements. The total power (flux) of a light source can be measured without inaccuracy caused by the directional characteristics of the source."
I don't know, the sun is pretty bright. . . .
Originally Posted by JohnJ80
There is a phone based light meter available that uses it's own hardware. I don't remember if it made it through the kickstarter phase, but it was a small light meter that plugged into your phone, rather than trying to use the camera sensor in the phone. It doesn't work with flash, but it's quite accurate for incident readings.
ah ha, here it is:
Lumu - bringing Light Meter to the 21st Century by Lumu Labs ? Kickstarter
Editor In Chief, "Internet Tough Guy Magazine"
"Home of Chuck Norris' Keyboard"
The remote sensor optimized for photography is (obviously) going to be much better unless they've really screwed that one up.
What this will give you is the lux - think of it as "lumen density" at any given part of the beam that hits the light meter. Total lumen output requires the integrating sphere as mentioned prior.
Lux measurements will allow you to map out the beam shape with repetitive measurements in different parts of the beam but won't tell you the total lumens. Total lumens requires an integrating sphere but it won't tell you anything about the beam shape.
And photographic beam shots won't be representative of the actual performance of the beam after about 400 lumen lights, in my experience.
I use a lux app on my android to do comparisons. Since the apps are not sensitive enough to do accurate comparisons at 1- meter I do 5-meter comparisons. You have to remember that whatever the meter shows is just measuring the brightest part of the beam pattern. This doesn't equate to lumen output but it is still useful when comparing the throw intensity of different lamps.
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