Lux Meter versus PAR meter

wds21921 · 07/12/2006, 09:09 PM

Since Lux measures ft. candle, would it give a better reading of actual drop in a bulbs intensity or is PAR much better and more accurate for this??

Can Lux meter be used and is there any way of converting it by calculation to get similar to PAR reading in anyway?

Boomer · 07/12/2006, 10:27 PM

As far as your observations and actual human light needs yes. As far as the actual light output not really. The human eye is most sensitive to 555nm. We do not see red and blue light very well. And the light meter is tuned to us so it does not see blue and red light very well either. A PAR meter see's it all more or less.

You still could use a light meter to get an idea on the amount of light output the bulbs have lost but it will not be as accurate. Neither will tell you how much of what light frequency you have lost, only a radiometric spectrophotometer can do that. That's the meter that makes all those nice colored graphs you see on light bulb specs ads.

Some what recently Sanjay did a nice piece explaining all this. Sanjay is to light what Randy is to chemistry in the reef hobby, unmatched

Making Sense of Light Measures
http://www.reefkeeping.com/issues/2006-04/sj/index.php

Make sure you check all the links that lead you to the other Parts

Bojan · 07/13/2006, 02:04 AM

Quote:

Originally posted by wds21921
Can Lux meter be used and is there any way of converting it by calculation to get similar to PAR reading in anyway?

You have to know that most of the low cost Lux-meters are actually not lux meters, because they do not use human-eye curve to measure intensity of light.

I have low cost lux-meter,which is quite accurate to measure daylight spectrum in lux units , but if spectrum is not daylight , measured values in lux are completely wrong.

Example

If I compare light intensity of the same model of the bulb (54W T5), with same reflector, same distance, I will read almost the same value for blue or actinic bulb as that for daylight bulb. It is obviously that this is impossible in lux units. So my low cost lux-meter is more PAR mater, than lux-meter.

wds21921 · 07/13/2006, 07:34 PM

Is there then anything reasonably priced that can be used or is this something thats going to wind up turning into another hobby?

Boomer · 07/13/2006, 08:38 PM

Bo

What light meter do you have ?

This is about the best one I've seen. Can out after I bought mine

http://www.omnicontrols.net/x407026.pdf

This is th one I bought
Extech EasyViewâ„¢ Light Meter EA30

Both are at http://www.omnicontrols.net/

wds

Here is a good article on PAR meters and what to expect
http://www.advancedaquarist.com/2005/7/review

Websites to buy

http://www.biocontrols.com/meter.html

http://webtrolley.org/mivastore/merc...egory_Code=BQM

http://www.forestry-suppliers.com/dr...y.asp?cat=1118

More on understanding light in the reef tank
http://www.coralreefecosystems.com/l...nical_data.htm

All you want to know about light measurement

The Light Measurement Handbook
http://files.intl-light.com/handbook.pdf

wds21921 · 07/13/2006, 10:35 PM

All I needed and more. Thanks Boomer.

bertoni · 07/13/2006, 11:15 PM

So you think the ExTech is better than the Quantum Meter? Is it more accurate?

Boomer · 07/13/2006, 11:31 PM

No, not even. If you want a meter for your tank a Q-Meter. If you want a meter for your tank and home lighting a Q/LUX meter (there is one on the "websites to buy" link that does both, I think it is $390.

The Extech I posted is about the best LUX meter I have seen. I do not have tanks anymore as you know but If I did I would have both but that is me. A year ago or so I gave my other light meter to Randy to play with and bought a new meter recently, to play with flashlight output ( another hobby of mine).

wds21921 · 07/14/2006, 10:23 AM

So would that make you an Ambiophil?

sfsuphysics · 07/14/2006, 10:32 AM

So what's the lowdown on the Milwaukee meter? It's $80, but is it complete crap?? I see a lot of the online aquarium stores selling it.

Boomer · 07/14/2006, 11:05 AM

That meter is set to the human eye more or less, like most ligh meters

Sensor is salt water compatible and measures a peak wavelength of 560 nm.

What is nice about this unit is it is waterproof, although I wish the cable was longer. It is a good meter for the money. Having a light meter is better than not having one at all

You can learn allot.

http://www.aquaticeco.com/index.cfm/...22118/cid/4305

wds21921 · 07/14/2006, 05:52 PM

I agree Boomer, at least it gives me an idea when the light itself is not performing as good.

Of course it won't tell me where in the spectrum it may be failing but I'm sure with at least one or two of the spectrums shifting severly it would hopefully still show up in the overall light intensity as deminishing?

Bojan · 07/15/2006, 02:04 AM

Quote:

Originally posted by Boomer
[B]Bo

What light meter do you have ?

I have ELVOS LM-1010 Luxmesser.

Boomer · 07/15/2006, 08:58 AM

No hits on googles

Billybeau1 · 07/15/2006, 10:33 AM

Thats because you dont speak Slovenian

steve the plumb · 07/15/2006, 04:44 PM

I just ordered the milwaukee model.I was wondering if spending $300 on a light meter is worth it for me.$86 cdn is affordable.I am looking more at when to change bulb plus when I am buying a coral can this give me a good idea as to what light its under.Do I need a better meter to give me that kind of info.Will I be happy with this model.Is it better to Buy a $200 meter.Will I get more out of it.The meter I saw on one site was $190 U.S.If so should I not buy the milwaukee?

sfsuphysics · 07/15/2006, 06:30 PM

Want to talk affordable??

http://www.advancedaquarist.com/2006/7/aafeature

Here ya go if you're curious about if your lamps are switching spectra, hell combined with the milwaukee meter you could get some nifty data.

wds21921 · 07/15/2006, 08:09 PM

Wow excellent find sfs, mucho de thanko.

Seriously, that combined with my lux meter should give me a good idea when the lights have exhausted there useable range.

bertoni · 07/16/2006, 12:31 AM

While we're on the subject of light meters, how about the LiCor 250 A with the Li-190 or Li-193 sensors?

Bojan · 07/16/2006, 02:07 AM

Quote:

Originally posted by Boomer
No hits on googles

I bought this device in Conrad, but I found that is not in the Conrad shop any more.

This one is quite similar

link

wds21921 · 07/16/2006, 07:22 AM

Dead Link

Bojan · 07/16/2006, 11:13 AM

I hope that this one wiil work

link

or use http://www1.int.conrad.com
and search LUXMETER MS-1300

Boomer · 07/17/2006, 10:10 AM

Mike

I just saw that I' going to order one

Jon

That is a very nice meter, does PAR and LUX. Which sensor

hard to pick. The 190 is going to show you more or less what your light bulbs are doing and plot you an SED curve (those colored graphs you see on light bulbs). The 193 is a whole different beast. It measures angular respond or the light hitting a sphere. The sensor is placed underwater and measures light in all directions that hit the sphere. The plotted light would remind you of a topo map on elevation. It would tell you, for example, how much light is hitting various parts of the aquarium or say a coral. It more or less produces a 3-D image of light. It does not measures PPDF but PPFFR (photosynthetic photon flux fluence rate). It will not show light spectra,i.e., 450nm ot 500 nm, just total light.

The LI-192SA, is more or less the same as the 190, only it is for underwater use. If you are interested in just what is going on with the light bulbs then the 193. If you want to see want those light bulb are going in the water of your tank then the 192. I think most would want to know what is going on in the water. Most of Sanjay's test are bulbs, in air and do not tell what you what the light from that bulb is underwater, 1 ft. down, 2 ft down, etc.., meaning light lose due to depth.

Me, I would e-mail or PM Sanjay and ask him

Me I think the 190. Like Sanjay I would like to see what bulbs do and not waht they do underwater. I do not think a ft or 2 is a big deal

Boomer · 07/17/2006, 10:37 AM

Bo

Found it, altough you can not get the instuctions in English.

You have to know that most of the low cost Lux-meters are actually not lux meters, because they do not use human-eye curve to measure intensity of light.

I do not know where you get this from. Most light meters/LUX meter, all that I know of, are set to a std, CIE photopic (CIE human eye response cure). Your own meter pdf shows this

Bojan · 07/17/2006, 01:24 PM

Quote:

Originally posted by Boomer
Bo,
I do not know where you get this from. Most light meters/LUX meter, all that I know of, are set to a std, CIE photopic (CIE human eye response cure). Your own meter pdf shows this

YES, but it is not true. I made very simple test

I tested
- T5 bulb with daylight spectrum and
- T5 bulb with the blue spectrum

Both bulbs have the same W , I use the same reflectors and i measured intensity of the light in the same distance. I get almost the same lux readings for both bulbs.

I know, that blue bulb have only the 20% of lumens compared with daylight bulb, because human eye is not very sensitive on blue light. So it obviously, that my LUX meter actually not measure LUX.

LUX readings are correct only for daylight spectrum. If spectrum is blue, my LUX meter show 5X more than real value.

07/12/2006, 09:09 PM	#1
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	Lux Meter versus PAR meter Since Lux measures ft. candle, would it give a better reading of actual drop in a bulbs intensity or is PAR much better and more accurate for this?? Can Lux meter be used and is there any way of converting it by calculation to get similar to PAR reading in anyway?

07/13/2006, 11:15 PM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	So you think the ExTech is better than the Quantum Meter? Is it more accurate? __________________ Jonathan Bertoni

07/13/2006, 11:31 PM	#8
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	No, not even. If you want a meter for your tank a Q-Meter. If you want a meter for your tank and home lighting a Q/LUX meter (there is one on the "websites to buy" link that does both, I think it is $390. The Extech I posted is about the best LUX meter I have seen. I do not have tanks anymore as you know but If I did I would have both but that is me. A year ago or so I gave my other light meter to Randy to play with and bought a new meter recently, to play with flashlight output ( another hobby of mine). __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

07/14/2006, 10:32 AM	#10
sfsuphysics Registered Member Join Date: Jan 2004 Location: San Francisco Posts: 9,103	So what's the lowdown on the Milwaukee meter? It's $80, but is it complete crap?? I see a lot of the online aquarium stores selling it. __________________ Mike

07/14/2006, 11:05 AM	#11
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	That meter is set to the human eye more or less, like most ligh meters Sensor is salt water compatible and measures a peak wavelength of 560 nm. What is nice about this unit is it is waterproof, although I wish the cable was longer. It is a good meter for the money. Having a light meter is better than not having one at all You can learn allot. http://www.aquaticeco.com/index.cfm/...22118/cid/4305 __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

07/12/2006, 10:27 PM	#2
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	As far as your observations and actual human light needs yes. As far as the actual light output not really. The human eye is most sensitive to 555nm. We do not see red and blue light very well. And the light meter is tuned to us so it does not see blue and red light very well either. A PAR meter see's it all more or less. You still could use a light meter to get an idea on the amount of light output the bulbs have lost but it will not be as accurate. Neither will tell you how much of what light frequency you have lost, only a radiometric spectrophotometer can do that. That's the meter that makes all those nice colored graphs you see on light bulb specs ads. Some what recently Sanjay did a nice piece explaining all this. Sanjay is to light what Randy is to chemistry in the reef hobby, unmatched Making Sense of Light Measures http://www.reefkeeping.com/issues/2006-04/sj/index.php Make sure you check all the links that lead you to the other Parts

07/13/2006, 07:34 PM	#4
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	Is there then anything reasonably priced that can be used or is this something thats going to wind up turning into another hobby?

07/13/2006, 08:38 PM	#5
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Bo What light meter do you have ? This is about the best one I've seen. Can out after I bought mine http://www.omnicontrols.net/x407026.pdf This is th one I bought Extech EasyViewâ„¢ Light Meter EA30 Both are at http://www.omnicontrols.net/ wds Here is a good article on PAR meters and what to expect http://www.advancedaquarist.com/2005/7/review Websites to buy http://www.biocontrols.com/meter.html http://webtrolley.org/mivastore/merc...egory_Code=BQM http://www.forestry-suppliers.com/dr...y.asp?cat=1118 More on understanding light in the reef tank http://www.coralreefecosystems.com/l...nical_data.htm All you want to know about light measurement The Light Measurement Handbook http://files.intl-light.com/handbook.pdf

07/13/2006, 10:35 PM	#6
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	All I needed and more. Thanks Boomer.

07/14/2006, 10:23 AM	#9
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	So would that make you an Ambiophil?

07/14/2006, 05:52 PM	#12
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	I agree Boomer, at least it gives me an idea when the light itself is not performing as good. Of course it won't tell me where in the spectrum it may be failing but I'm sure with at least one or two of the spectrums shifting severly it would hopefully still show up in the overall light intensity as deminishing?

07/15/2006, 08:58 AM	#14
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	No hits on googles __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

07/15/2006, 10:33 AM	#15
Billybeau1 Registered Member Join Date: Jul 2005 Location: Dyer, Indiana Posts: 12,010	Thats because you dont speak Slovenian

07/15/2006, 04:44 PM	#16
steve the plumb Moved On Join Date: Apr 2005 Location: Montreal, Canada Posts: 3,664	I just ordered the milwaukee model.I was wondering if spending $300 on a light meter is worth it for me.$86 cdn is affordable.I am looking more at when to change bulb plus when I am buying a coral can this give me a good idea as to what light its under.Do I need a better meter to give me that kind of info.Will I be happy with this model.Is it better to Buy a $200 meter.Will I get more out of it.The meter I saw on one site was $190 U.S.If so should I not buy the milwaukee? Last edited by steve the plumb; 07/15/2006 at 04:55 PM.

07/15/2006, 06:30 PM	#17
sfsuphysics Registered Member Join Date: Jan 2004 Location: San Francisco Posts: 9,103	Want to talk affordable?? http://www.advancedaquarist.com/2006/7/aafeature Here ya go if you're curious about if your lamps are switching spectra, hell combined with the milwaukee meter you could get some nifty data. __________________ Mike

07/15/2006, 08:09 PM	#18
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	Wow excellent find sfs, mucho de thanko. Seriously, that combined with my lux meter should give me a good idea when the lights have exhausted there useable range.

07/16/2006, 12:31 AM	#19
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	While we're on the subject of light meters, how about the LiCor 250 A with the Li-190 or Li-193 sensors? __________________ Jonathan Bertoni

07/16/2006, 07:22 AM	#21
wds21921 Registered Member Join Date: Apr 2003 Location: Elkton, MD Posts: 1,442	Dead Link

07/16/2006, 11:13 AM	#22
Bojan Registered Member Join Date: Feb 2004 Location: Slovenia Posts: 969	I hope that this one wiil work link or use http://www1.int.conrad.com and search LUXMETER MS-1300

07/17/2006, 10:10 AM	#23
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Mike I just saw that I' going to order one Jon That is a very nice meter, does PAR and LUX. Which sensor hard to pick. The 190 is going to show you more or less what your light bulbs are doing and plot you an SED curve (those colored graphs you see on light bulbs). The 193 is a whole different beast. It measures angular respond or the light hitting a sphere. The sensor is placed underwater and measures light in all directions that hit the sphere. The plotted light would remind you of a topo map on elevation. It would tell you, for example, how much light is hitting various parts of the aquarium or say a coral. It more or less produces a 3-D image of light. It does not measures PPDF but PPFFR (photosynthetic photon flux fluence rate). It will not show light spectra,i.e., 450nm ot 500 nm, just total light. The LI-192SA, is more or less the same as the 190, only it is for underwater use. If you are interested in just what is going on with the light bulbs then the 193. If you want to see want those light bulb are going in the water of your tank then the 192. I think most would want to know what is going on in the water. Most of Sanjay's test are bulbs, in air and do not tell what you what the light from that bulb is underwater, 1 ft. down, 2 ft down, etc.., meaning light lose due to depth. Me, I would e-mail or PM Sanjay and ask him Me I think the 190. Like Sanjay I would like to see what bulbs do and not waht they do underwater. I do not think a ft or 2 is a big deal

07/17/2006, 10:37 AM	#24
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Bo Found it, altough you can not get the instuctions in English. You have to know that most of the low cost Lux-meters are actually not lux meters, because they do not use human-eye curve to measure intensity of light. I do not know where you get this from. Most light meters/LUX meter, all that I know of, are set to a std, CIE photopic (CIE human eye response cure). Your own meter pdf shows this __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.