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light meter questions

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mike View Drop Down
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  Quote mike Quote  Post ReplyReply Direct Link To This Post Topic: light meter questions
    Posted: 07 February 2008 at 03:37
i got an environmental concepts plant light meter the one measures in foot candles never realy understood how it works and was wandering if any one knows a way of makeing sence of it at the recomended distance for the light when measured it read 5,000 foot candles but at right next to the bulb it reads no higher then 7,500 foot candles since i broke this back-out today i moved my clfs in a pattern that no plant was bathed in less then 3,000 foot candles but the ones that are in the lower light get hit by light from at least 5 differant dirrections just useing the clfs till they all start to take off and are big enough to turn on the hid right now while vegging them with 2 4' dual tube fixtures with 40 watt bulbs i got 4 150 watt clfs and 4 120 watt clfs both the clf's are the 10 bucks a single bulb at wal-mart for a grand total of 1240 watts to veg in a 6' by 2' space got anouther set of dual tube fixtures for the 2 longer walls when they get tall enough once they get a lil bigger i will be redoing the space ie moveing all the cords out of the way and turning on the 400 mh probably in the next couple of weeks
help my plant's fell over and can't stand up
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Ganja View Drop Down
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  Quote Ganja Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 11:32
I've wondered about using a lux-meter myself, more to see how much difference in lumen output between new and old HID bulbs.

I can't offer much help on reading the meter, since I've never used one, but what was the problem with the reading of 5000fc vs 7500fc right at the bulb?

AFAIK, fluorescent light is useful in that a large proportion of emitted lumens are useable by the plant, but the downside is that fluoro light isn't very useful to plants that are more than about 1m from the tube/bulb.
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mike View Drop Down
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  Quote mike Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 17:31
i was wandering if that was a good reading i also noticed at the same distances that the 150 watt clf matches my 400 watt hid only real differance is that the hid penatrates more
help my plant's fell over and can't stand up
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  Quote Ganja Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 18:31
Unless the 400w HID is very old, it should be emitting a lot more light than the CFL at a given distance.

Is it possible your meter is only sensitive to certain spectrums/wavelengths of light?
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mike View Drop Down
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  Quote mike Quote  Post ReplyReply Direct Link To This Post Posted: 07 February 2008 at 23:12
i'm not sure if it is or not its just the little hand held thing conected to a sensor not evan battery operated
help my plant's fell over and can't stand up
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