Hi Ian,
I was mentioning to someone on a previous thread that even the light meter in a DSLR camera can be used - - but you need to calculate a calibration curve for the meter's response. There is an journal article written by NEC where they developed the calibration curve for a Nikon D3000 as a low cost alternative to high end PAR meter for researchers who do not have the budget to purchase the meter. They compared the readings with a high end meter and were within 8% of the expensive meter readings. The Apogee meter is also within 8% of high end meters.
Cheers,
HI,
In theory works, if you guess how much you put in each RGB channel. Camera light meters are accurate for this kind of reading.
i also thought that you could use a (rgb light sensor) dslr camera to measure PAR, but...
- Cameras read reflected light, PAR meters take direct readings. Make accurate reading from reflected light is more difficult and less accurate.
- If you want incident light, putting camera inside the tank can be tricky to make some readings. You could have a grey card reference to take more precise readings, maybe...
- Ceg could you give the link to that article? i'm interest in it.
- Any idea about using a RGB sensor, and how much weight for each channel? Maybe R 20% G 10% B 70%?
- I've made some readings with and apogee along with a normal (cheap) Lux Light Meter.
For LED's the conversion factor is quite stable. For RGB light's can have some variation, but once you get the factor for a specific light you have the KEY.
I think you read the measures that me and Nuno Matos made with a few LED's, not a professional test but enough to give a comparative idea.
There are a few guides in apogee about using their PAR sensors, even table conversions for some type of led's.
cheers