Thread View: sci.aquaria
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Started by George Booth
Fri, 20 Nov 1992 19:28
Information about lights
Author: George Booth
Date: Fri, 20 Nov 1992 19:28
Date: Fri, 20 Nov 1992 19:28
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9975 bytes
I recently made some intensity and color temperature measurements on a
bunch of fluorescent and metal halide bulbs and would like to share
the data with you.
My goal was to determine the relative brightness of various bulbs (to
check out the claims of the vendors) and to get a feel for the color
temperature of the bulbs. A secondary goal was to determine the
effects of age on both color temperature and brightness.
To measure intensity, I used a lux meter offered by Marine
Invertebrates, Inc. This is advertised in FAMA and costs about $100.
I'm not sure about its absolute accuracy, but, being digital, its
resolution is quite good. The instructions claim an accuracy of +/- 5
lux and it seems very repeatable. I'm also not sure about how color
temperature affects its accuracy. Its response curve peaks at about
600 nm, so there is probably some effect.
To measure color temperature, I rented a Minolta Color Meter II from a
photographic supply store in Denver. It's primary use is to determine
the correction filters required to balance a specific film for a
specifc light source, but it also indicates color temperature in
degrees Kelvin. I'm not sure of its absolute accuracy (and I did see
some strange results with metal halide lights), so take the numbers
with a grain of salt. This is a neat instrument that sells for about
$700, so I feel that numbers aren't too far off for the fluorescent
bulbs. Minolta also makes a different meter for "scientific and
industrial colorimetery", but it's not available for rental locally.
BTW, I tried to call the Minolta Customer Service Department to determine
the validity of my measurements, but the "representative was busy and
his voice-mail was full", so I couldn't leave a message.
This posting is the raw data I collected. I have not as yet drawn any
conclusions aside from obvious things like Penn-Plax Ultra TriLux
bulbs are brighter than Triton bulbs and they have a color temperature
closer to sunlight (whether or not that is good, I'm not saying).
Perhaps one of the net light experts could comment on the data.
--------
George
=====================================================================
Light Fixture Effects
---------------------
To determine if the light fixture and ballast affected the temperature
and intensity, 2 new 40 W Cool White bulbs (2 for $2.49) were tested
in two fixtures. The readings were taken 8" from the bulbs, centered
over the middle of the fixture.
An "electronic" shop light ($15.99 at Ace hardware) with a small coil/
capacitor ballast circuit produced 5000 K and 5500 Lux. This is an
"energy saving" type fixture. My experience indicates this type of
fixture is hard on bulbs such as Tritons and shortens their life.
As a side note, the October '92 Consumer Reports tested various types
of energy saving light bulbs including compact fluorescent bulbs with
electronic and magnetic ballasts. They found that a large number of
the bulbs with an electronic ballast had premature failures.
A "standard" Sears shop light with a normal magnetic ballast produced
5300 K and 6650 Lux. The same fixture with aluminum foil behind the
bulbs produced 5300 K and 7900 Lux. Also with this setup, the color
temperature ranged from 5200 K to 5500 K when the distance from the
bulb varied from 3" to 24".
I also tried to check the lights in a Coralife metal halide and
fluorescent fixture to see if an "expensive" ballast and polished
reflector did anything, but the bulb spacing was very different giving
readings which could not be meaningfully compared to the first three.
Conclusions:
1) Cheap electronic fixtures reduce your light intensity and bulb life.
2) Cheap reflective material can increase your light intensity.
Color Temperature (single bulbs)
--------------------------------
I had hoped to determine color temperature and aging effects of metal
halide bulbs, but the temperature meter responded very strangely to
most of the bulbs I tested, giving readings of 9000 K to 14000 K
depending on the distance from the bulb. One older, 1000 W MH bulb
read 6200 K, but I don't have much faith in that number. By the way,
an actinic bulb caused an "overrange" reading (above 40000K).
The local fish store allowed me to check some of the bulbs in the
store. Most of the bulbs are about 1 year old. I was surprised at
the temperature range of the 40 W Power-Glo bulbs; possibly caused by
differing age or fixture differences or just bad quality control - I
don't know. I believe the higher K temperature indicates more blue,
which shows up some fish colors better.
20w Ultra TriLux 5200 K new (in a cheapie hood)
Phillips UltraLume 5800 K 6 months
Artic Brite 6000 K 1 year
Power-Glo 7200 K
" " 7850 K
" " 8700 K
" " 8700 K
" " 9350 K
" " 9800 K
A local lighting store has a light bulb comparison center with various
commercial bulbs. The age of the bulbs was unknown. Unfortunately,
the store was remodeling and some of the display was not working, so I
didn't get a chance to try a Chroma 75.
Warm White Delux 3460 K
Warm White 3630 K
Regal White 3640 K
Natural 3900 K
Spectra 35 3930 K
Spectra 30 3930 K
Chroma 50 4600 K
Cool White 5000 K
Cool White 5150 K
Daylight 7500 K
We have quite a few bulbs of various ages on hand. Each was tested in
the Sears shop light. The second bulb in the fixture was covered with
a piece of cardbard so it would not affect the readings. The age of
the the bulb is indicated, if it was known. All readings are 8" from
the bulb.
Agro Lite 3590 K
Wide Spectrum 3900 K
Advantage X 5300 K 5100 K in electronic fixture
Artic Brite 5850 K new 5900 K in electronic fixture
" " 5700 K
Ultra TriLux 6750 K new
" " 6350 K 6050 K in electronic fixture
" " 6150 K
" " 6150 K
Triton 8150 K new
" 8400 K new
" 7550 K 300 hours
" 7550 K
" 7350 K 4800 hours
Color Temperature (combinations)
--------------------------------
Combinations of bulbs in use on our various plnated aquariums were
tested. The average age of the bulbs is about 6 months.
1 Power-Glo,
1 Ultra TriLux 6550K
1 Triton, from
1 GE Wide Spectrum, 6000 K
1 Triton, to 6300 K
1 Ultra TriLux to 6500 K
1 Ultra TriLux, from
1 Ultra Trilux, 6150 K
1 Triton, to 6050 K
1 Ultra Lume to 5900 K
1 Artic Brite,
1 Ultra TriLux 6400 K
Intensity (single fluorescent bulbs)
------------------------------------
From the local fish store (meter was 4" from the bulbs except for the
metal halide bulb):
1000 W Metal Halide, 12" from fixture 69,000 Lux
2 Power-Glo bulbs, 11,000 Lux
1 Power-Glo, 1 Ultra TriLux 8,200 Lux
1 Power-Glo, bad fixture 2,400 Lux
From the local lighting store (meter was 4" from the bulbs):
Regal White 3300 Lux
Chroma 50 3500 Lux
Warm White 4600 Lux
Cool White 5000 Lux
Our bulb stock (meter was 8" - twice as far - from the bulb):
Wide Spectrum 2400 Lux
Artic Brite 3750 Lux new 2780 Lux in electronic fixture
" " 3200 Lux
Advantage X 4200 Lux 3370 Lux in electronic fixture
Triton 3890 Lux new
" 3820 Lux new
" 3730 Lux 300 hours
" 3610 Lux
" 3300 Lux 4800 hours
Ultra TriLux 5000 Lux new
" " 4720 Lux 3520 Lux in electronic fixture
" " 4580 Lux
" " 4480 Lux
Intensity (single 5500 K metal halide bulbs)
--------------------------------------------
We have had our dual 175W metal halide fixture in use for over 1 year
and have tracked the intensity of 3 of the 5 bulbs in use over that
period. The bulbs are on for 10 hours per day.
Directly below the bulb at the acrylic shield:
Bulb 1: 78,000 90 to 270 days
72,000 320 days
57,000 360 days
Bulb 2: 126,000 10 minutes
110,000 4 hours
102,000 2 days
94,500 4 days
90,000 13 days
90,000 21 days
86,500 62 days
82,000 110 days
72,000 285 days
60,000 315 days
At the water surface, 13" from the bulb:
Bulb 2: 9,900 Lux 1 year old; replaced at this point
Bulb 3: 19,900 Lux after 2 hours
17,600 1 day (12 hours)
17,100 2 days (22 hours)
16,900 3 days
16,400 4 days
15,700 6 days
15,700 16 days
I was very surprised at the rapid initial drop off of intensity from
the MH bulbs; I had expected a linear drop for most of the lifetime.
The data indicates that MH bulbs should be changed once a year if
you have intensity sensitive applications.
Re: Information about lights
Author: Anthony Tse
Date: Sun, 22 Nov 1992 05:00
Date: Sun, 22 Nov 1992 05:00
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In article <2520051@hplvec.LVLD.HP.COM> booth@hplvec.LVLD.HP.COM (George Booth) writes:
>I'm also not sure about how color
>temperature affects its accuracy. Its response curve peaks at about
>600 nm, so there is probably some effect.
That will surely affect your data if you are interested in PAR
output, specially for reef application where red light is pretty
useless. However, it will give a good indication on how bright the bulbs
are.
>
>To measure color temperature, I rented a Minolta Color Meter II from a
>photographic supply store in Denver. It's primary use is to determine
>the correction filters required to balance a specific film for a
>specifc light source, but it also indicates color temperature in
>degrees Kelvin. I'm not sure of its absolute accuracy (and I did see
>some strange results with metal halide lights), so take the numbers
>with a grain of salt. This is a neat instrument that sells for about
>$700, so I feel that numbers aren't too far off for the fluorescent
>bulbs. Minolta also makes a different meter for "scientific and
>industrial colorimetery", but it's not available for rental locally.
The Minolta Color Meter II should be fairly accurate since a few
hundred degrees off can really screw things up if you are a pro
photographer shooting slide. I can't explain why you got such strange
color temperature reading. A few things can possibly affect the reading,
room light and color of the reflector came to mind, a white reflector to
most people is not white to a photographer who is willing to pay $700
for a meter to check color temperature. But some of your readings are
really really strange. There exist widgets that measure spectral ouput
of lamps and give you a plot of output power vs wavelength. I think we
actually have one here at the lab, but I don't think they want me to
haul in a bunch of flourescent lamps and measure them, it's much eaiser
to call the lamp manufacturers and ask them to send you their
measurements, assuming you are buying "normal lamps" where companies like
Phillips, GE, OSRAM, etc will gladly mail or fax you any info you want.
>This posting is the raw data I collected. I have not as yet drawn any
>conclusions aside from obvious things like Penn-Plax Ultra TriLux
>bulbs are brighter than Triton bulbs and they have a color temperature
>closer to sunlight (whether or not that is good, I'm not saying).
Color temperature has very little to do with how close the spectral
output of a bulb is to sunlight. Sunlight has a continious spectrum
across the visible spectrum, whereas a 5500K (or 6500K or whatever)
triton has 3 narrow spikes, one in blue, one in green and one in red.
The human color visual system consists of three overlapping bandpass
filters, one center at blue, one at green and one at red, our brain
takes the AMPLITUDE output of these three filters and assign a color to
it, that is why you can create any color with three monochromatic
sources (RGB or CYN) for the HUMAN VISUAL system by varying the relative
amplitude of the three colors. And since photographs are for humans to
look at, all the color meter care about is the relatively amplitude
output of the three bandpass filters, it doesn't care whether or not the
bulb put out a continious spectrum, it certainly doesn't care whether or
not the three color spikes coming out of all these tri-phosphorous bulbs
are usful for plant growth or not. So a picture that look perfectly
good to us human under a 5500K triton will look completely out of wack
to other species with different sets of color filters. In short, an
AX50 has one output spike at 430nm, one at 540nm and one at 620nm and
these three spike combine to give you a 5000K color temperature, but if
photosynthesis occur between say 470nm to 500nm (which are not correct
numbers), then the AX50 will be useless for plant growth even though it
has the right color temperature. In conclusion, your safest bet is to
use bulbs such as vita-lite (which I know most people don't like because
it is not "white" even thought the spectral output of a vita-lite is
about as close to the sun spectral as one can get, and because sales
critters can make more money by selling you "reef bulbs" whose spectral
output are nowhere close to the sun's spectrum). Chroma50 and Chroma75
are also safe bets because they are vita-lite with a extra blue
spike. I use the words safe bet because the vita-lite and the chroma
bulbs best simulate sun light and plants and corals just happen to live
under the sun. For all I know, plants and corals maybe perfectly happy
living under blue actinic light as long as you have enough of it to
satisify their photosynthetic need. The choice between using full spectrum
bulbs or tri-phos bulbs is yours, I have one tank lit with ColorTone50s
(Phillips verson of Chroma50) and actinics, another tank lit with
tri-phos compact flourescents (the 40W job, not the little 9W thing)
and actinics, I much prefer the ColorTone50 tank even though the
tri-phos compact flourescents are much brighter (almost as bright as
the AX50 per watt).
>I was very surprised at the rapid initial drop off of intensity from
>the MH bulbs; I had expected a linear drop for most of the lifetime.
>The data indicates that MH bulbs should be changed once a year if
>you have intensity sensitive applications.
I posted this about a year ago and got everybody really upset
because I was telling them they've been fooled by all the sale hype of
MH. Anyone can call OSRAM and get them to fax you data sheets on their
MH. The Lumen Maintenance curve furnished by OSRAM on their 250W 5400K
MH clearly shown that MH lumen drop off extremely fast and not linearly.
The output drop to 70 percent of initial after ~3000 hours and stay
there until the bulb burn out. But of course, the advistised lumen
output are always initial lumens which will last maybe a couple of
hours. Flourescent lamps on the other hand drop at a MUCH slower rate,
for example, an Ultralume will maintain 95% of its initial output after
3000 hours and 80% of its initial output after 26000 hours. How the
statement "flourescent lamp became noticably dimmer after 6 months
and need replacement while MH will maintain their output for much longer
thus only need replacement every two years" came about is beyond me.
Even the actinic03 will maintain 80% of its initial output after 3000
hours. And if a stock OSRAM 9W blue bulb is 5 times brighter then the 40W
actinic03, then I must have a very serious eye problem, cause my
moon light is a 9W OSRAM blue and it's nowhere near as bright as a
single actinic03.
-Anthony
PS One of these days I will control myself and stay out the lighting
discussions.
-------
Disclaimer: Those are my opinion and mine alone. They have nothing
to do with the company I work for.
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