# Questions tagged [lumen]

The Lumen is a measurement of the intensity of light.

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### measure luminanace with lux meter

can we measure luminance in cd/ m² with a lux meter? I measured illuminance of 35 lux. and since cd = lux*distance² I took some distance of 30 cm and got 3.15 cd. I know that my led-grid surface is ...
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### How can I automatically get a (approximate) Lux value from overexposed and underexposed pictures?

As you will soon understand, I am not a photographer. For research in a completely different field, I am interested in estimating, even with a large approximation, the brightness of the environment in ...
3k views

### How to compute luminous intensity in a photograph?

I have a photograph in raw format taken by a Nikon D-90 camera of a white LED spotlight shining on a wall in an otherwise dark room. I need to compute the relative luminous intensity of the bright ...
1k views

### Recalculating lux or lm from EV [duplicate]

I have to calculate amount of light from IR emmiter. The only equipement, that I can use is Sekonic Light Meter like this one: http://www.ebay.com/bhp/sekonic-l-358 The problem is that i need to have ...
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### How can I measure luminance values from different cameras?

Calculating EV and then Lx is pretty simple. The problem starts when trying to calculate these by using EXIF data that come from different cameras. I tried capturing a static object in the exact ...
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### Brightness of LED panel [duplicate]

If choosing a xenon flash, GN is a common reference. Come to led panel, there is lm/m and lux. This is a spec. of led panel: LM: 520/m LUX: 1m: 650, 2m:170, 3m:80 Whats EV equivalent of above ...
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### What is the lowest level of luminous flux a camera can detect?

In the past, I've asked about taking photos of luciferase. Now I'm curious how weak of a light source I can detect. From How many photons per second is one Lumen? on Physics Stack Exchange, I can ...