catching the light of the moon

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djozz
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catching the light of the moon

Tonight the sky is very clear over Amsterdam, with an almost full moon shining om my balcony (as photographed above through binoculars). Which gave me the opportunity to try something that I was pretty sure of that it would not work: recording a moon spectrum on my handheld spectrometer.

The minimum illuminance that it can record a spectrum of is about 10 lux. So I concentrated the light with some cheap plastic magnifyer and behold, it worked. The projection of the moon on the sensor was made as sharp as possible and was a bit smaller than the sensor surface of the spectrometer, so I think that chromatic abberations of the magnifyer were reasonably averaged with the rest of the light by the diffusor of the sensor so I rather trust that it is an accurate spectrum of the moon as it shines over Amsterdam tonight.

So here it is, how fun is that! And no PWM was measured Smile

Edited by: djozz on 09/23/2018 - 19:25
CRX
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Smile
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Awesome! It’s amazing that the CCT is 4253K, moonlight always appears a lot cooler.

djozz
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gravelmonkey wrote:
Awesome! It’s amazing that the CCT is 4253K, moonlight always appears a lot cooler.

I just looked it up, there ‘s more people who noticed that. Here’s the long answer (but a good read): https://physics.stackexchange.com/questions/244922/why-does-moonlight-ha...
Boaz
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   That's cool ....

 

  I mean neutral 

 

 4253K  can be a really a nice tint 

 

 Hey DJOZZ have you contacted the manufacturer? If there is a group buy I'm in for 2 .

 

   "The Purkinje effect makes us perceive faint light as bluer (higher colour temperature) than we would perceive a brigher light with an identical spectrum"

  << this may explain why Hi Cri lights look much better on med. or high compared to low or moon modes.

       καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

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    Still selling diffuser film  >…  http://budgetlightforum.com/node/42208

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djozz wrote:

Moonbeam Love! Wink

EasyB
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CRI snobs. Facepalm Thumbs Up

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98 CRI & 4253K – I knew there was a reason I was such a lunatic about hi-cri at those temps

Move towards the light.

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It would be nice if LED light bulbs came in 4250K with 98 CRI. That’s pretty much perfect for both indoor and outdoor lighting. I generally never see anything between 3000K and 5000K in stores though, so I have to mix multiple bulbs to get the right temperature.

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First, djozz, super cool to know this. Like others, I would have thought it cooler as well.

ToyKeeper wrote:
It would be nice if LED light bulbs came in 4250K with 98 CRI. That’s pretty much perfect for both indoor and outdoor lighting. I generally never see anything between 3000K and 5000K in stores though, so I have to mix multiple bulbs to get the right temperature.

TK, not sure if you have a Rural King in your area, but I just picked up a couple boxes of ‘Tool Shed’ brand LED bulbs rated at 4000K. Cheap brand, I’m sure, but I surprisingly liked them so much, I picked up an extra box and replaced all my basement bulbs with them. They are ‘just right’.

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Wow, pretty neet. Seems the moon sets a good standard for leds to try and match. I’m surprised to see the red part of the spectrum is so full.

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electricjelly wrote:
Wow, pretty neet. Seems the moon sets a good standard for leds to try and match. I’m surprised to see the red part of the spectrum is so full.

The link in post #4 gives some good information on the physics behind moonlight and the perception of it.
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Here in Australia 90+cri 4000k bulb are common but the tints seems much cooler than a 4000k maybe its the white plastic diffuser they use.

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Djozz, do you have a jar big enough to fit your spectrometer?

If so, you should take another measurement, and take pictures of the process. Because it would prove that you actually caught moonbeams in a jar.

djozz
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ToyKeeper wrote:
Djozz, do you have a jar big enough to fit your spectrometer?

If so, you should take another measurement, and take pictures of the process. Because it would prove that you actually caught moonbeams in a jar.


That sounds like a wonderful thing to do.
I do have a jar big enough, but how to push the button while the spectrometer is inside?, sure the moonbeams will try to escape if I keep the lid off. Smile
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The light from the moon is reflected sunlight , Grad

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gravelmonkey wrote:
Awesome! It’s amazing that the CCT is 4253K, moonlight always appears a lot cooler.

The ambient light from the moonlight is so dim that you are using your rod cells, not your cone cells, hence you are not perceiving that the ambient light is in fact warmer/yellower than the ambient light under sunlight (light of the sun + light from the sky (blue)).
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Tally-ho wrote:
gravelmonkey wrote:
Awesome! It’s amazing that the CCT is 4253K, moonlight always appears a lot cooler.
The ambient light from the moonlight is so dim that you are using your rod cells, not your cone cells, hence you are not perceiving that the ambient light is in fact warmer/yellower than the ambient light under sunlight (light of the sun + light from the sky (blue)).

Yeah I assumed that was the case, djozz replied with a pretty good link in post #4.

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As others have said, I’ve always found this to be the sweet spot for CCT at night time and roughly 3B tint for daytime (about 5200K). The latter is apparently the CCT at sunrise/sunset .. It’s always cool to see these preferences and ‘attractions’ be correlated to things in nature.

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JaredM wrote:
As others have said, I've always found this to be the sweet spot for CCT at night time and roughly 3B tint for daytime (about 5200K). The latter is apparently the CCT at sunrise/sunset .. It's always cool to see these preferences and 'attractions' be correlated to things in nature.

 

 I've heard Jon Slider talking about this too and have problems understanding people talking about using flashlights during the day ...Just makes no sense to me .If i use a flashlight in the day it's for 11 seconds to find my pen that fell behind the stereo speaker.tint isn't an issue at that point . where do people use a light in the day ?

       καὶ τὸ φῶς ἐν τῇ σκοτίᾳ φαίνει καὶ ἡ σκοτία αὐτὸ οὐ κατέλαβεν

                                  https://www.gty.org/

 

    Still selling diffuser film  >…  http://budgetlightforum.com/node/42208

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This thread got me thinking about how the amount of moonlight (reference a full moon at latitudes < 40 degrees from the equator) compares to what we call “moonlight mode” (typically less than a lumen). Perhaps a different thread?

PocketSammich wrote: I don’t need this, but I want it. Please sign me up.

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stupid thread got me doing a 6 hr study on black body and quantum physics.

Thanks now i'm more confused .

 

reading is hard

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    Still selling diffuser film  >…  http://budgetlightforum.com/node/42208

djozz
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Last night I recorded another full moon:

Apparently the one full moon is not the other. This time it was warmer, 3400K. The luxvalue was lower than the first recording in september last year. It is attractive to speculate that more haze in the atmosphere (the sky looked very bright though) caused more scattering (affects blue the most) and warming up the CCT. Or the moon was lower than last time (it was), so the light travels a longer distance through the atmosphere, again more scattering.

Whatever the reason, the CCT of moonlight seems pretty variable, but the CRI is invariably high. Let’s wait for a very high moon next time and see what the CCT does then.

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This was very interesting, I had no idea this could be done. Thank you.

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Funny how no one mentioned the positive DUV. I’m surprised you guys can stand to go outside without it being rosy negative DUV Facepalm

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contactcr wrote:
Funny how no one mentioned the positive DUV. I’m surprised you guys can stand to go outside without it being rosy negative DUV Facepalm

That’s why I wear Lee minus green filters in my glasses Cool

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Nice read Djozz, looking forward to the next.

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MAybe they are using a new clone moon emitter Smile
T
The Chhinaaa man must have caused it. LOL

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Quote:
the moon was lower than last time (it was), so the light travels a longer distance through the atmosphere

I just saw that as an explanation for why this month’s full moon looks more pink — it rises only to the lowest angle above the horizon.

I’ve seen some wonderful outdoor time exposures of Yosemite waterfalls made with moonlight. They make “moonbows” too dim for the eye that cameras can capture.

https://www.google.com/search?client=firefox-b-1-d&channel=tus&q=moonbow...

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contactcr wrote:
Funny how no one mentioned the positive DUV.


There’s no need to mention it.

Everyone already knows the moon is made of green cheese.