Light meter

[Kennpmel]

Why can't I use a light meter for LEDs?

[Dutchman1]

They sell light meters specifically for leds on amazon.

[Weed Pharma]

A standard light meter reads the white light humans see.
If the LED is nothing but white led's you can use it, otherwise you need a PAR meter (what the plant benefits from), but most LED manufactures have already done that for you in chart form.

You only need to keep the distance within the recommended range for success.

I tend to use the range towards the longest distance, except the last 2 weeks in flower.
ie manufacturer flower range 10-16 inches - I would flower at 14" until last two weeks then move to 12".

[DrPhoton]

Almost Standard photometric meters (lux for example) measure the light weighted with the sensitivity of the human eye. As such the meter only gives useful information on the efficacy of light to humans. We can use it for sodium discharge lamps because most produce similar spectrums. So there is little variability. Other light technology such as LED have different spectrums compared to other technologies but also between themselves with different products. So measurements will vary and be inconsistance. With quantum PAR meters, it is an unweighted measurement. So you will get consistant results no matter the technology.

[Kennpmel]

Looks like I lucked out! The meter I bought measures both Lux and Par. Thanks guys.

[baddog]

Kennpmel , would mind sharing which meter that is ?

[D.A.A.S.69]

I didn't know that they even made a combination like that.
I hear people say they use their smart phones apps for light meters,