Measuring Florescent light output

[The Peloric Orchid]

I strongly recommend buying a lux or footcandle meter. I got one for around twenty bucks on Amazon (just remember that there's around 10 lux per footcandle). That way you can take the guesswork out of light placement. The main downside with these kinds of meters is that they're calibrated to more sensitive in the green/yellow range, much like human eyes, so they won't measure colored light accurately. The alternative is to buy a PAR quantum light meter, but these are much more costly and there's less data about orchid growth in light levels measured in micro einsteins.

[Stray59]

Again - WOW !I am amazed that something so widespread in it's use seems to be so complicated to properly implement. You guys keep up the discourse. This is all WAY over my head so I will keep monitoring until it gets really simple - I am a little . And a lux meter sounds like what I need to invest in. Any suggestions to brand or what to look for exactly?
Steve
p.s. - what in the heck is a micro einstein?

[The Peloric Orchid]

Since most meters are for lux measurements, I recommend one that's rated for at least 50,000 lux (which converts to around 4600 footcandles). That way you can make measurements all the from low light to something that's beyond the brightness require of bright light orchids. Unless you're into professional photography, you don't need to spend more than $35 dollars on a light meter.

A micro einstein is basically a measurement of the number of photons. As far as plants are concerned, most photons that fall within visible light are suitable for photosynthesis, so color doesn't matter in terms of a plant being unable to photosynthesize and quantum light meters are calibrated to reflect this.

Even though I have science background, the math and physics behind light went over my head too the first time I tried doing this. When I was trying to figure out what wattage (before I knew about lumens, lux, and footcandles) lights I needed, I realized that there wasn't enough data out there to make an exact calculation, so I bought a brighter light than I guessed that I needed figuring I could always mount it higher.

[Stray59]

The Peloric Orchid:
Thank you for the explanation. I am really non-mathematical; I always focused on psychology and orchids, or for that matter, anything besides math. I had a traumatic experience involving formulaic equations I think - I've all but blocked it from my mind. Needless to say, I am much better with epiphytic roots than square roots. I do have a Rhynchostylis that grew a square root, but I think it was just a fluke !
The answer to my question is a light meter. This is the simplest and most logical solution as I am sure every light bulb configuration, the distance of the bulbs, hood color, etc. makes a difference and a meter will show me what the plants are getting in my (their) home.
Thanks again for the help!
Steve

[DavidCampen]

Originally Posted by The Peloric Orchid

I strongly recommend buying a lux or footcandle meter. I got one for around twenty bucks on Amazon ... The main downside with these kinds of meters is that they're calibrated to more sensitive in the green/yellow range, much like human eyes, so they won't measure colored light accurately. The alternative is to buy a PAR quantum light meter, but these are much more costly and there's less data about orchid growth in light levels measured in micro einsteins.

The PAR light meters just do not have the green filter that other light meters have. The frequency response of a photocell without a filter is fairly flat so a green filter is added to make the response more closely match that of the human eye.

The inexpensive light meter that I bought on Amazon had a green filter that I easily removed. Of course, that messes up whatever absolute calibration the meter may have had but if you only care about comparing relative values for varied light sources - sunlight, fluorescent, red LED etc. it now matches the PAR meter response.

[Stray59]

Good info to know - I am still in the undecided stage at this time, so I will still just monitor the conversation as see how this develops - I am either somewhat understanding what everyone is saying, or becoming delusional and in that case this really doesn't matter does it? I am leaning toward the meter you are talking about. Any idea of the name of the distributor?

Steve

P.s. I finally found a place to use the chicken emoticon - Yes!

[samarak]

Regarding PAR meters vs. the regular lux/FC meters, I have both, because I'm one of those geeky people. But unless you are, too, I'd go with a lux/FC meter. They are much cheaper, they're perfectly adequate for most people, and virtually all orchid growers and articles about orchids still use foot-candles or lux in the discussion. Few people will know what you're talking about if you mention microeinsteins.

I went to Amazon and just put in "light meter" and got a hit on a 0-200,000 lux (roughly 0-18,500 FC) for $40 US. There's a cheaper one ($25 US) that's 0-50,000 lux (0-4600 FC) but that's a very limited range - it will do for measuring fluorescent lights but once you start measuring you'll want to measure all kinds of light exposures. A sunny day in summer here in NW Arkansas exceeds 12,000 FC, and the unshaded part of my greenhouse can easily be >9000 FC. For the small difference in price, I'd get the better meter.

It's not essential, of course, there are lots of really good growers who have never touched a light meter, but I think you'll have fun with it. And probably learn some things about your setup you wouldn't have otherwise.

Steve

[SueinNC]

Pardon me for butting into this thread but what about the light meters for androids and other phones, has anyone had any experience with those?

[Calbears]

Originally Posted by naoki

The unit on the graph is probably correct. Here is my measurement, which matches well with Ray's.

http://www.orchidboard.com/community...tml#post572079

Naoki,

For some reason the link is going to the "Orchids in Frog Vivariums" thread but I did see your post and I'm disappointed my 4x4' t5 ho fixture will have to almost touch my plants during this coming winter.

Thanks

[Ray]

Originally Posted by Calbears

Naoki,

For some reason the link is going to the "Orchids in Frog Vivariums" thread but I did see your post and I'm disappointed my 4x4' t5 ho fixture will have to almost touch my plants during this coming winter.

Thanks

That graph was from a single, 2', 24W bulb. Your 4 x 4' fixture, having 4 x 54W bulbs - 9x the light output.

No, you're not going to have to put the lamp that close the the plants.