Wow, those numbers are impressive, Brooke. I'm surprised the fall off is so great without the reflectors.

The book I studied from before setting up my basement lights suggested (for HIDs), that you could use a lower wattage, (say 400 instead of 600 or 1000) and place them near enough together so the area of light coverage overlapped.

That creates a third area of high light *between* the two lights. In that way two or three 400W placed correctly create a much bigger high light area than a larger-watt bulb (and cooler as well, so you can place the plants nearer)

I set up my Wonderlites the same way, to create a high light area between pairs of them.

Hope that's clear. Don't know a better way to say it.

Did you create a higher light area where they overlap or did the area return to the same intensity as directly under the HID light. Hope THAT makes sense.

Brooke

Isn't this what they are trying to do with the LED set-ups?

I think I remember reading on one site that they are positioned so that the light from the individual LEDs overlap one another. They didn't state that the reason was to increase the intensity, but with those low power consumption and low heat generating things, why not stack them tight if it increases the intensity.

Bob

Bob I agree that is the intent of the LEDs, or what I skim read through, but the problem as I saw it was you needed so many to replace other light systems, the cost was prohibitive. Between the cost of the set-up and the cost to run a lot of them, big dollars were involved. Maybe eventually it can rival the others, but not now on a dollar to dollar basis.

Brooke

Thank you highjack! I was certain I was losing light -- I'm glad you did that test. There is a local hydroponics shop nearby. I will check out their reflectors. Meantime, I like your idea of foil to extend the reflectors I do have. Liz

Good luck Liz - let us know if the hydro store has something useful for your set-up. The homemade foil extenders weren't pretty, but they worked. Anything to keep an orchid happy!

Brooke

T-5 Fluorscent Hi-Bay come with mirror reflectors, parabolic, really great lights for power and small light loss. Just put 3" blinds on the sides (foil covered) and you have 42" by 3' of a real sunburst. Hard to find, Graingers has them, expensive but real performers. I think they come in 4, 6, and 8 tube and can be 72" fixtures, mine are. Anyway that is my 2 cents worth! ;-)) By the way LOWE'S sells reflectorized tape that is a great replacement for foil.

The readings above are inaccurate.

No commercially produced 40w bulb exists with an 8000 lumen rating, neither home or industrial usage.
CFL's twice the size are approximately 7000 initial lumens.
Commercially produced 40w cfl's are in the 3000- 3600 lumen range regardless of K rating.

At a distance of one inch from the bulb 2347 footcandles is being delivered to the plant.
[NIST Certified meter]

*Note: Lumens = Footcandles at 0 distance.
Degredation at a fraction of an inch is significant.

A 40w bulb is a 40w bulb, spiraled or straight.

We thought it a benefit to new orchid growers to ammend the above measurements.
CV
Drs Charles and Vanessa Varzsegy MD, Phd

Clara I don't see anywhere in the above post where the word lumens was mentioned. Lumens and footcandles are not the same.

A footcandle is a light intensity measurement and a lumen is a light flux measurement - light per unit time.

Agreed a 40 watt bulb whether curly or straight, takes the same amount of energy to produce light. The CFL light is concentrated in a much smaller area whereas the straight tube produces the light over a longer area, but less intensity over the entire length.

Who is Drs. Charles and Vanessa Varzsegy MD, PhD and is their degree in light measurement? A light meter works great for me.

Brooke

This'll be useful - I'll take some measurements from my 65W this weekend and post similar measurements for comparison. I am also in the process of setting up my bank of T5s so I can take some measurements from those too...this will be a good resource for anyone interested in setting up lights.

Brooke - your measurements with and without the reflector definitely show the importance of reflectors - someone on another forum showed the same thing with T5s actually - it makes a huge difference! Just for the record, I have *heard* that aluminum foil is bad material for making reflectors, as no matter how smooth you get it, it still scatters the light undesirably. Apparently, plain white is the best reflective material - it would be interesting to try the measurements with either 3" tin foil extenders, or 3"white paper extenders.

Lacontessa - I was also a bit confused about the lumen-foot candle thing...hard conversion to do but I found: http://www.lightingdesignlab.com/articles/metrics_quantity/metric_quantity.htm
(very good diagram!).

From what I've read, essentially foot candles/lux is a measurement of the amount of light that falls on a certain area (aka intensity) whereas lumens is simply the quantity of light flying out of a source. 1000 lumens spread over 10 feet = 100 foot candles. 1000 lumens spread over 1 foot = 1000 foot candles. 1000 lumens spread over 0.1 foot (which is roughly what you get right up at the bulb) = 10,000 foot candles.

If the lumen rating on bulbs describes essentially the amount of light flying out of the bulb, then it I'm not sure you're correct in saying that lumens = foot candles at 0 feet....theoretically, by the definition of foot candles as light landing over an area, as your area approaches 0 (which will happen as you move closer and closer to your point source) your foot candles can approach infinity as the amount of light your outputting is concentrated over a smaller and smaller area.

Btw - is this actually clara from before with the big bertha?? why the name change?!?

1 fc = 1 lumen per square foot

I believe (if understand what I read correctly). Someone please correct me if I'm wrong.

Now say 3000 lumens is the total light output of the bulb. The problem here is that this is total light output in all directions, so not all 3000 lumens will travel to your lightmeter/plant. If we were able to direct the entire output of the bulb to 1ft by 1ft (that is 1 foot away from the bulb) section of plants those plants would be receiving 3000fcs. Unfortunately light escapes and we're not that good a controlling it (and you probably want to cover more than a 1x1 section of plants. So I am going to verify for you Brooke's measurements at 12" with a reflector.

Assumptions:
Bulb lumen output (from package) = 3600 lumens
Bulb's + reflectors footprint at 12" away = approx. circle of radius 1.5 feet = PI*(1.5*1.5) = 7 sq ft
All light output from bulb is directed at footprint, lumens emitted away from the surface are bounced back towards it by the reflector.

Calculation:
footcandles = lumens / area covered by light
= 3600 lumens / 7 sq ft
= 514 footcandles

Of course, no lighting system is this perfect, so a good chunk of the light is lost, to me the 450 fc measurement seems completely logical.

Yes Calvin, it's actually clara aka CV(Drs Charles and Vanessa Varzsegy MD, Phd / whatever), aka mike_gee, aka little_stars, etc, etc.

WoW!

Amazing what a little well-placed light can do.

Thanks, Brooke!

Sc

Calvin: the light book I read also mentioned that flat white is the best light reflector, why I painted my light room flat white. I would have assumed gloss paint, but as you say, that would probably scatter the light everywhich way. I don't remember now if that was compared to specially treated materials.

Also, about T5's. I love the look of T5's-- just so sleek and bright-- that I plan to install some in my light room this fall. One of the light movers died, and I'm not going to replace it. The T5's would cover some of the now-unlighted area. More easily raised and lowered on a pulley, too. The HID's require real muscle to raise or lower.

I'm thinking about them for my west window, too, for the same reasons.

So I would really appreciate you sharing all the information you collect about your T5's once installed. From your own measurements and whatever you read as well.

It's that time of year again! Some of this info is useful!

Who is Drs. Charles and Vanessa Varzsegy MD, PhD and is their degree in light measurement? :-)