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[Urban Elements]

Perhaps I should study these a bit more to be sure I'm getting it right.  I have to do some more testing because, although I got some encouraging readings last evening,  I have not been able to get consistent readings today.
Pictures:
1.  The box the inexpensive analog meter came in.  From the description, it looks like everything I wanted and seems to respond to changing light conditions well.
2.  First app I downloaded,Whitegoods,  has calibration ability and when I calibrated it to the analog meter last evening, it seemed to work well.
3. Second downloaded app, Lux Camera, cannot be calibrated, but last evening the first reading looked good.
4. Comparison of analog reading with Lux camera first reading.

I'll try some other apps and update if I figure it out.

The analog meter you have is for reading footcandles .

[Urban Elements]

You should be more focused on PAR  reading.
I think Lux is mainly used for photographers.

I mentioned that before and it is partially true, because:

Sunlight does always havethe same spectrum (might chang a little bit when its clowdy) therefore we can compare the lux readings we get from sunlight and compare it. Cheap.

On the other side, when it comes to artificial lighting you are correct: There is no point in getting lux readings from our LEDs, MHs, CFLs ... and compare them, that would require a $$$ PAR meter.

Europe PAR = 0.48 x Solar radiation and in North America PAR = 0.45 x Solar Radiation.
It is generally accepted that: 1800 micromols m-2 s-1 ≡ 427 W m-2 but this equation was estimated for sunlight.

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[BubbleCat]

0.45 and 0.48, close enough for our purposes

I bet thats well in the tolerance of any affordable device anyway, especially apps.

[plantlight]

The analog meter you have is for reading footcandles .

It has a lux scale as well as a footcandle scale.  I'm not an expert but it appears to be simply a unit of measure.

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[plantlight]

You should be more focused on PAR  reading.

I appreciate your comments   and for artificial lighting, I would agree but we're measuring sunlight.

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[Urban Elements]

You should be more focused on PAR  reading.

I appreciate your comments   and for artificial lighting, I would agree but we're measuring sunlight.

Lol... https://en.m.wikipedia.org/wiki/Photosynthetically_active_radiation

https://en.m.wikipedia.org/wiki/Lux

[plantlight]

Lol... https://en.m.wikipedia.org/wiki/Photosynthetically_active_radiation

https://en.m.wikipedia.org/wiki/Lux

Not sure what is funny.  I agree when using artificial lighting that can be controlled it would be an advantage to measuring photons.  However, since I grow outdoors my requirements are more simple.  I don't think there is much that I can control except perhaps the maximum intensity of sunlight my plants are exposed to. 

What do you have in mind?

[Urban Elements]

Lol... https://en.m.wikipedia.org/wiki/Photosynthetically_active_radiation

https://en.m.wikipedia.org/wiki/Lux

Not sure what is funny.  I agree when using artificial lighting that can be controlled it would be an advantage to measuring photons.  However, since I grow outdoors my requirements are more simple.  I don't think there is much that I can control except perhaps the maximum intensity of sunlight my plants are exposed to. 

What do you have in mind?

I laughed due to a comment that's posted in that link.

PAR measurement is used in agriculture, forestry and oceanography. One of the requirements for productive farmland is adequate PAR, so PAR is used to evaluate agricultural investment potential.

[plantlight]

Yeah, saw that.  Probably of value when considering initial growing location.  Unfortunately, I'm stuck where I am, right now with very little growing space.   Mostly I'm concerned with Psychotria viridis and proper placement in my mostly shady yard.

[plantlight]

I think that this is the area where PAR meters are superior to LUX.

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[BubbleCat]

Actually it depends. If the LEDs are suitable for plants the PAR meter will give it a much higher rating compared to the tubes. That is because the LED, if made specifically for plants, will exactly target those areas with narrow spikes in bandwith that a PAR meter would account for with a factor close to 1, whilst the  tubes emit light over a wide bandwith including such light as green that a PAR meter will acoubt for with a factor close to 0.
Also make sure they iluminate the same area when testing.

Again: When we want to compare DIFFERENT light sources we either need a PAR meter or a lux meter and a graph that shows the wavelengths emitted by said light sources and some math.

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[BubbleCat]

Have a Mimosa ? Mine closed leaves about when Lux dropped below 100.

[Urban Elements]

Have a Mimosa ? Mine closed leaves about when Lux dropped below 100.

Haha, we use a sensitive mimosa at the nursery to check things like temp fluctuation and light intensity.  Just drop one in a location of question and check it after the day ends.

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[BubbleCat]

Yeap, on some other thread someqhere on here I mentioned pretty much doing the same, I use my mimosa as an indicator of light mainly