Light meters

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GCase

El Colibri
Sep 16, 2011
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Wonder if members have tried a light meter like the one below. Appears they do get expensive with multi-features.

Does anyone know how it operates. Lots of positive reviews, yet, not a single how to use video or articles on internet. Appears one needs some understanding of lux/foot candles. Read operating manual and gives no real information on how to set up for a reading.

Is this a useful piece of gear to check grow tent lighting intensity.

Thanks for input.

http://www.amazon.com/Dr-Meter-Digital-Illuminance-Light-LX1330B/dp/B005A0ETXY
 

namvet25

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It cant be that hard to use.It should have a lumen reading for flouresent and cfl readings and a par reading for LED readings.
 

arty zan

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The meter in your link measures Lux not Lumens so a conversion is needed to convert from one to the other.

Most light meters measure LUX and to find the lumen measurement you need to do a conversion calculation to lumens.

Some LUX meters have a conversion button which is very helpful and are only slightly higher in price than a straight LUX meter.

The difference between LUX & Lumens & how to convert LUX to Lumens

Light intensity measured on a plane at a specific location is called illuminance. Illuminance is measured in footcandles, which are workplane lumens per square foot. You can measure illuminance using a light meter located on the work surface where tasks are performed. Using simple arithmetic and manufacturers' photometric data, you can predict illuminance for a defined space. (Lux is the metric unit for illuminance, measured in lumens per square meter. To convert footcandles to lux, multiply footcandles by 10.76 this is the easy way to convert).

Here is a link to a LUX to Lumen calc - http://www.ledstuff.co.nz/data_calculators.php

If converting from LUX to Lumens the LUX to Lumen calc is the easiest way to do the conversion, unless your a maths wiz who loves to work things out.{serious maths, I wouldn't bother spending time doing this, it's the calc all the way for me http://www.rapidtables.com/calc/light/how-lux-to-lumen.htm}.

​Measuring PAR

AS Nam correctly pointed out when measuring the light from an LED you will need to use a PAR Meter.

PAR Meters are not cheap , Apogee's Quantum PAR Meters start at around £240 / $360 which is out of a lot of peoples price range.

Here is a link to make a cheap DIY PAR meter from a cheap light meter - https://www.autoflower.net/forums/f28/cheapest-par-meter-diy-40206.html#post770348
 
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namvet25

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Thanks Arty,very good info.
 

Corgy

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The meter in your link measures Lux not Lumens so a conversion is needed to convert from one to the other.

Most light meters measure LUX and to find the lumen measurement you need to do a conversion calculation to lumens.

Some LUX meters have a conversion button which is very helpful and are only slightly higher in price than a straight LUX meter.

The difference between LUX & Lumens & how to convert LUX to Lumens

Light intensity measured on a plane at a specific location is called illuminance. Illuminance is measured in footcandles, which are workplane lumens per square foot. You can measure illuminance using a light meter located on the work surface where tasks are performed. Using simple arithmetic and manufacturers' photometric data, you can predict illuminance for a defined space. (Lux is the metric unit for illuminance, measured in lumens per square meter. To convert footcandles to lux, multiply footcandles by 10.76 this is the easy way to convert).

Here is a link to a LUX to Lumen calc - http://www.ledstuff.co.nz/data_calculators.php

If converting from LUX to Lumens the LUX to Lumen calc is the easiest way to do the conversion, unless your a maths wiz who loves to work things out.{serious maths, I wouldn't bother spending time doing this, it's the calc all the way for me http://www.rapidtables.com/calc/light/how-lux-to-lumen.htm}.

​Measuring PAR

AS Nam correctly pointed out when measuring the light from an LED you will need to use a PAR Meter.

PAR Meters are not cheap , Apogee's Quantum PAR Meters start at around £240 / $360 which is out of a lot of peoples price range.

Here is a link to make a cheap DIY PAR meter from a cheap light meter - https://www.autoflower.net/forums/f28/cheapest-par-meter-diy-40206.html#post770348
There is an Android app, Lightning Calculations https://play.google.com/store/apps/details?id=it.Ettore.calcoliilluminotecnici&hl=en dunno if it is available in a fruity version.

Also take a look here https://www.autoflower.net/forums/f149/mephisto-led-vs-hps-sour-crack-af-sog-40118.html#post770619 for light measuring apps, from post #35.
 

arty zan

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I second that. Appreciate your insight. Appears need to keep watch for a unit to measure LED PAR.

Cheers
Here is a link to the cheapest Apogee Quntum Light PAR Meter £222.48 / $334.14

It has been a while since I last looked at these meters and the price seems to have come down a bit, I'm sure last time I looked {over a year ago} they were about £300 or so.


http://www.ebay.co.uk/itm/Apogee-Quantum-Light-Par-Meter-MQ-200-/331249116681?pt=LH_DefaultDomain_0&hash=item4d1ffc6609



Product Review: Apogee Instruments' PAR Meter (Model MQ-200) and Software

By Dana Riddle
The Apogee MQ-200 Quantum Meter offers many advantages to aquarium hobbyists. The meter is relatively inexpensive (as quantum meters go) and the submersible sensor is small and allows measurements to be made in tight spots. Hobbyists should take a careful look and see if this PAR meter is for them.




A question I commonly ask during a presentation is 'How many own a PAR meter'? I am often pleasantly surprised to learn that light measurement is coming more common among reef hobbyists. Still, those using a PAR meter are in the minority - which I find interesting. Undoubtedly, those not making light measurements will fret over calcium concentrations or pH levels, while leaving light intensity levels unchecked. This is interesting still - excessive light is expensive, beginning with the purchase of the lighting fixture and continuing with operational costs and peripheral expenses, such as water chilling. More importantly, excessive light can inhibit coral growth and, in extreme cases, kill them.
For those unfamiliar with these light measuring devices, Photosynthetically Active Radiation (PAR) is those wavelengths between 400nm and 700nm (violet to red light) that promote photosynthesis. A PAR meter reports the number of photons (light particles) within this bandwidth of light as Photosynthetic Photon Flux Density (PPFD), in units of micromole photons per square meter per second (µmol photons·m²·sec, or simply µmol·m²·sec). Older literature might report PPFD in units of microEinsteins per square meter per second, or µE·m²·sec. No conversion is necessary as 1 µmol·m²·sec = 1 µE·m²·sec. Maximum PPFD near the equator at noon on a clear day is ~2,100 µmol·m²·sec.
For years, PAR meters (or more properly, quantum meters) were used by only research scientists. To my knowledge, one of the first public aquariums to use one was SeaWorld Ohio. It was an aquarist there, Pete Mohan, through his writings in FAMA magazine, who introduced me to the concept of PAR measurements within an aquarium. My interest (obsession) lead to a purchase of a Li-Cor quantum meter and underwater sensor in the mid 1990's (at the tidy sum of $1,500. I recently upgraded to a Li-Cor 1400 data logger and underwater sensor at the cost of almost $3,400.) In any, case Apogee Instruments (Logan, Utah, USA) would release a few years later a much more affordable PAR meter costing only $200 or so. This would revolutionize the way hobbyists measured light intensity within their aquaria. These meters have gone through several iterations, and this review will focus on the latest from Apogee Instruments - the MQ-200 Quantum Meter. This device has been upgraded considerably over the older model Apogee meter I own.

Copied and pasted from
http://www.advancedaquarist.com/2013/9/review



 

GCase

El Colibri
Sep 16, 2011
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I see now for us--par is the key, otherwise, we are just measuring light intensity and not what our plants thrive on--specifically.

Cheers
 

lavaman

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Sep 20, 2016
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This is a great thread. Here's my question. Now that we know how to get accurate readings, what numbers am I looking for? In other words, what is the optimum light requirements for plants? Obviously, LED, HPS, incandescent, natural sunlight are all different methods to get the plant light, so are there a specific numbers of LUX/PAR numbers we should be looking for?