lux meter

[doctaq]

would a cheap lux meter thats like 20 bucks do anything as far as accuracy?
the real number i am interested in is par from leds specifically xr-e or xp-g cool whites and royal blues. i figure if i get some kind of lux measurement from a led and match it up to a par measurement some kind of correlation can be found and i can build and test led flashlights and arrays in terms of lux and par respectively
does any of this make sense?
par is basicly light from 400-700nm

 

[shilent]

I'm interested in this too. I don't need anything super accurate, just something that will tell me if flashlight A is brighter than flashlight B. Hard to tell with these different tints. Another example I'd need it for is if a flashlight is brighter with other batteries.

 

[doctaq]

exatly, or testing reflectors or optics or something on the same led

 

[csshih]

well, the problem is with the different tints and the cost of the luxmeter. often, cheaper luxmeters will not have a photopic curve response filter -- some tints will read higher than others
....but, the "inaccuracy" should be reasonable consistent.

now, if you're measuring with the same LED, a cheap luxmeter will be fine.

...although, with PAR, a RB LED will measure much much lower than a white one on a meter with a photopic response filter.. :thinking:

 

[doctaq]

but will the degree of change be consistent? i guess, i could pose this question to a reef forum which is what my underlying motive is anyways muhaha

 

[csshih]

haha. I thought so.
trying to light up coral, hm?

The degree of change should be consistent. although, I'm pretty sure PAR is measured differently than just a simple lux meter.