9 ms·

One thing: most LEDs suck at mimicking daylight. The cheap ones are bad at delivering the full light spectrum. The higher end of LED is slowly getting there. T

by atoav 4y ago

One thing: most LEDs suck at mimicking daylight. The cheap ones are bad at delivering the full light spectrum. The higher end of LED is slowly getting there. The measurement one should be looking for there is CRI ("Color Rendering Index"). The sun has a CRI of 100. Any lightsource above 90 to 95 CRI is (to my experience) indistinguishable from daylight. The best stuff there currently is are (of course) the Skypanels by ARRI for laughable 6800 USD per panel (film equipment is expensive as usual). Blasting a 2.5 kW HMI lamp ("Hydrargyrum medium-arc iodide lamp") trough a window from the outside is a good emulation of daylight. So good in fact that the poor souls shooting films inside will have their bodies in confusion as they exit the room and realize in horror that it is dark outside. The electrical bill of anything emulating the sun is no joke tho.

korm 4y ago
Very true, color rendering, or god forbid flicker, are the main culprits to me. Over the last few years a ton of players have entered the film lighting space, with many offerings exceeding Arri's color rendering for far cheaper. Yuji LEDs or iFootage for example make some of the most accurate lights at 98+ cri. The film industry will still go for Arris for other reasons, but at home we have lots of options nowadays. Amazon listings will always claim ridiculous cri numbers, try to find a 3rd party measurement. https://indiecinemaacademy.com/complete-led-color-database-cri-tlci-cqs-tm30-15 https://indiecinemaacademy.com/complete-led-color-database-c.... https://youtu.be/qCyKdIgRVTk https://youtu.be/qCyKdIgRVTk
- xxs 4y ago
  >or god forbid flicker That's just terrible drivers - likely an unisolated AC with a single coil. Flicker is trivial to defeat sacrificing the power factor (just add filtering caps). Overall there is nothing hard about using constant driven high-freq (over 30KHz, so no sound interference, either) LEDs. Side note: in the days of home video calls, you can tell how many have terrible lights as the flicker is visible on the even camera.
  - dx034 4y ago
    The problem just is that it's really hard to find good LEDs. Maybe they're all being sold to industrial consumers, but it's been a pain to find good LEDs if you're looking for anything more "exotic". E.g. dimmable LEDs work and are available, but there is so much cheap trash out there while good brands are often sold out. And for many sockets, there's maybe one manufacturer offering it, if at all. I've had instances where only cheap vendors offered LEDs for a certain socket.
    - xxs 4y ago
      Hmm, It'd appear you wish to retrofit LEDs in existing fixtures. That's the rub - they are not designed to work well - there is so much space for a LED driver + LEDs + cooling + looking nice. Most LEDs are overdriven to show higher lumen numbers (and watts) on the tin, which means a short life. Dimmable LEDs with a standard triac based dimmer for incandescent bulbs is a bad idea overall. The decent LED fixtures are designed to be a single unit, e.g. near ceiling light, dimmable w/ remote/blue tooth. Unfortunately, not possible to replace parts of them, and if they are poorly built - also overdriven. OTOH, they are trivial to repair with some electronics background - often times, the driver is replaceable entirely. LEDs need to stay cool (below 60C) to have prolonged life - say 40K hours to stay at 80% brightness. That means large heatsinks, enough space to dissipate the heat.
      - dx034 4y ago
        I've already replaced dimmers to work with LEDs. But changing all fixtures would be way too expensive, it'd then be cheaper to just stick with Halogen. And I don't need any "smart" features, an LED that can be dimmed via an external dimmer would be enough. But they're harder to find than all these "smart" devices that might stop working after a few years and can send data to who-knows-who.
        LargoLasskhyfv 4y ago
        Check these out: [1] https://www.osram.com/ecat/Professional%20LED%20lamps%20with%20filament-style%20LED%20technology-LED%20lamps-Lamps-Digital%20Systems/com/en/GPS01_3122242/ https://www.osram.com/ecat/Professional%20LED%20lamps%20with...
Youden 4y ago
There are plenty of high-CRI LEDs available at reasonable prices. Bridgelux [0] and Yuji [1] are a couple of examples off the top of my head. So I don't believe it's the LEDs that are the problem. And yes, by modern standards they can suck some juice but even a large ARRI Skypanel only draws 1500W [2], which is similar to a small air conditioner. [0]: https://www.bridgelux.com/ https://www.bridgelux.com/ [1]: https://www.yujiintl.com/ https://www.yujiintl.com/ [2]: https://www.arri.com/en/lighting/led/skypanel/s360-c#F0.00S360C https://www.arri.com/en/lighting/led/skypanel/s360-c#F0.00S3...
- MengerSponge 4y ago
  I added some Sunlike LED bulbs (the GE "sun filled" brand) to my office a few months ago. They aren't expensive, and they are nowhere near as bright as true daylight, but they do the trick. Sunlike LED elements are available in different formats around the world: http://www.seoulsemicon.com/en/technology/sunlike/casestudy/ http://www.seoulsemicon.com/en/technology/sunlike/casestudy/
- onion2k 4y ago
  And yes, by modern standards they can suck some juice but even a large ARRI Skypanel only draws 1500W [2], which is similar to a small air conditioner. Why would you compare it to an air conditioner though? Those aren't equivalents. You need to compare it to an alternative light source. A bright LED bulb uses about 13W. You could have 10 of them and still be using less than 1/10 of the energy...
  - klodolph 4y ago
    The reason you'd compare it to a small air conditioner is because it's an amount of power that you can get from a branch circuit at home. Normal indoor LED lighting is almost a rounding error on your electricity bill these days. Daylight simulation uses much more power.
    - thrashh 4y ago
      But why would you compare when the goal is not to maximize your power usage before tripping a breaker. It is to get light.
zxcvbn4038 4y ago
The trick my local bar uses is to put artificial lights behind a stained glass window. No matter what time you go in it looks like late afternoon, about an hour before sunset. Unless you have a watch or line of sight to the outer door when someone opens it, you can’t tell what time it is. I’ve never seen behind the stained glass but am guessing they have warm light fluorescent bulbs (no heat) and something diffusing the light because it looks evenly distributed. There are no windows on the outside of the building so it seems something you can set into a wall.
- ehnto 4y ago
  Our casino takes a different approach, block all the sunlight so that no matter the time of day, the artificial light is the same.
  - sokoloff 4y ago
    After a very long day playing poker, I walked into the Sky Ceiling area in the Venetian and had a really strong feeling that something was very wrong. (It was probably 2 AM, but the room is convincing enough to make it feel like late afternoon and the disconnect was strong enough that I had to leave the area.)
thrashh 4y ago
A lot of people barely notice poor CRI lights. Heck people will mix bulbs of different color temps and not even bat an eye. The issue is definitely the power usage. It’s not reasonable to dedicate that much power for the relatively minimal gain. Also, CRI is a relatively poor measurement of color quality because it measures a very desaturated color palette. You can have two high CRI lights and they will still not match. There are newer color rendering indices like TLCI, SSI and TM-30 to account for this.
- atoav 4y ago
  Good comment, thanks. Yeah you are right. I tried to simplify this as much as possible while still providing the gist of "various white light sources can have a different coverage of the light spectrum".
- marvin 4y ago
  Ultimatly, what matters is how the light spectrum looks. CRI is just an attempt at reducing that to a single number. Even then, many «daylight» scenes have very different light spectra.
  - thrashh 4y ago
    While daylight definitely varies, I believe the spectra for the sun at noon at sea level is reasonably even and would be the main goal (as opposed to mimicking daylight in the morning or towards the arctic). CRI doesn’t measure vibrant red very well and human skin has that red.
- scythe 4y ago
  Wouldn't mixing bulbs at different colors improve the color rendering? Unless they're the same underlying substrates in different ratios (diode+phosphor), I guess, but I don't think they usually do that.
  - deleted 4y ago
    [deleted]
- 4y ago
prox 4y ago
Do these lights also stimulate vitamine D production?
- saalweachter 4y ago
  UVB is what's required, I believe. 290 to 315 nm.
  - rapjr9 4y ago
    Right, sunlight contains UVA and UVB and the UVB is what creates vitamin D. An indoor light that outputs UVB could be dangerous, the equivalent of laying outside in the sun all day, every day. It would also quickly degrade many materials in your house. UVA would trigger photosensitive eyeglasses turning them dark. Sperti makes a vitamin D lamp and it has a five minute timer and comes with UV blocking goggles (not sure what intensity it is relative to the sun) which suggests significant risk. So you may not want any forms of UV inside your home. Many windows these days have glass formulated to block UV to protect your rugs, drapes, and furniture. I'd question whether anyone would want the IR spectrum from an indoor sun-light also. I think what most people would want would be a high CRI light that has enough blue to trigger the brains time keeper. A bright indoor daylight-like light will make everything look very stark though (black shadows, objects brightly lit so you see all the fingerprints, scratches, and dust everywhere.) Your eyesight may degrade faster if you are constantly in brightly lit areas also. You may find that your autistic friends stop visiting you (or ask you to turn the lights off.) A lot of people who built A-frame houses with floor to ceiling windows at the end of the house found out that all that light entering 1) makes the house really hot 2) interferes with reading, watching TV, and using computers 3) fades their furniture and rugs. Even without the UV, bright indoor light has some issues, though it certainly can brighten dark spaces.
kodisha 4y ago
This made me think how little I actually think deeply about things. I read an OP question, and was like, meh there must be something out there. Then I read your answer, and was like, ohhhh this makes total sense. Of course you can't have equivalent of THE SUN for $50 and consuming couple of watts per day.
valenterry 4y ago
One thing about CRI is reflection though. When you use an LED with a high CRI then when it illumates your furniture, objects, people etc. it will look like as if the sun shines on it (in terms of colors). But what I would like to have is indirect light. E.g. point the lights to the ceiling and have the ceiling illumate the rest of the room. Not only is this less efficient in terms of electricty (but there isn't really a way around it) but it AFAIK also impacts the CRI depending on what material the ceiling/mat is made of. Any insights here?
- sparker72678 4y ago
  High quality glass diffusors so at least the light is more indirect?

by atoav 4y ago

korm 4y ago

Very true, color rendering, or god forbid flicker, are the main culprits to me. Over the last few years a ton of players have entered the film lighting space, with many offerings exceeding Arri's color rendering for far cheaper. Yuji LEDs or iFootage for example make some of the most accurate lights at 98+ cri. The film industry will still go for Arris for other reasons, but at home we have lots of options nowadays. Amazon listings will always claim ridiculous cri numbers, try to find a 3rd party measurement. https://indiecinemaacademy.com/complete-led-color-database-cri-tlci-cqs-tm30-15 https://indiecinemaacademy.com/complete-led-color-database-c.... https://youtu.be/qCyKdIgRVTk https://youtu.be/qCyKdIgRVTk

xxs 4y ago
>or god forbid flicker That's just terrible drivers - likely an unisolated AC with a single coil. Flicker is trivial to defeat sacrificing the power factor (just add filtering caps). Overall there is nothing hard about using constant driven high-freq (over 30KHz, so no sound interference, either) LEDs. Side note: in the days of home video calls, you can tell how many have terrible lights as the flicker is visible on the even camera.
- dx034 4y ago
  The problem just is that it's really hard to find good LEDs. Maybe they're all being sold to industrial consumers, but it's been a pain to find good LEDs if you're looking for anything more "exotic". E.g. dimmable LEDs work and are available, but there is so much cheap trash out there while good brands are often sold out. And for many sockets, there's maybe one manufacturer offering it, if at all. I've had instances where only cheap vendors offered LEDs for a certain socket.
  - xxs 4y ago
    Hmm, It'd appear you wish to retrofit LEDs in existing fixtures. That's the rub - they are not designed to work well - there is so much space for a LED driver + LEDs + cooling + looking nice. Most LEDs are overdriven to show higher lumen numbers (and watts) on the tin, which means a short life. Dimmable LEDs with a standard triac based dimmer for incandescent bulbs is a bad idea overall. The decent LED fixtures are designed to be a single unit, e.g. near ceiling light, dimmable w/ remote/blue tooth. Unfortunately, not possible to replace parts of them, and if they are poorly built - also overdriven. OTOH, they are trivial to repair with some electronics background - often times, the driver is replaceable entirely. LEDs need to stay cool (below 60C) to have prolonged life - say 40K hours to stay at 80% brightness. That means large heatsinks, enough space to dissipate the heat.
    - dx034 4y ago
      I've already replaced dimmers to work with LEDs. But changing all fixtures would be way too expensive, it'd then be cheaper to just stick with Halogen. And I don't need any "smart" features, an LED that can be dimmed via an external dimmer would be enough. But they're harder to find than all these "smart" devices that might stop working after a few years and can send data to who-knows-who.
      - LargoLasskhyfv 4y ago
        Check these out: [1] https://www.osram.com/ecat/Professional%20LED%20lamps%20with%20filament-style%20LED%20technology-LED%20lamps-Lamps-Digital%20Systems/com/en/GPS01_3122242/ https://www.osram.com/ecat/Professional%20LED%20lamps%20with...

Youden 4y ago

There are plenty of high-CRI LEDs available at reasonable prices. Bridgelux [0] and Yuji [1] are a couple of examples off the top of my head. So I don't believe it's the LEDs that are the problem. And yes, by modern standards they can suck some juice but even a large ARRI Skypanel only draws 1500W [2], which is similar to a small air conditioner. [0]: https://www.bridgelux.com/ https://www.bridgelux.com/ [1]: https://www.yujiintl.com/ https://www.yujiintl.com/ [2]: https://www.arri.com/en/lighting/led/skypanel/s360-c#F0.00S360C https://www.arri.com/en/lighting/led/skypanel/s360-c#F0.00S3...

MengerSponge 4y ago
I added some Sunlike LED bulbs (the GE "sun filled" brand) to my office a few months ago. They aren't expensive, and they are nowhere near as bright as true daylight, but they do the trick. Sunlike LED elements are available in different formats around the world: http://www.seoulsemicon.com/en/technology/sunlike/casestudy/ http://www.seoulsemicon.com/en/technology/sunlike/casestudy/
onion2k 4y ago
And yes, by modern standards they can suck some juice but even a large ARRI Skypanel only draws 1500W [2], which is similar to a small air conditioner. Why would you compare it to an air conditioner though? Those aren't equivalents. You need to compare it to an alternative light source. A bright LED bulb uses about 13W. You could have 10 of them and still be using less than 1/10 of the energy...
- klodolph 4y ago
  The reason you'd compare it to a small air conditioner is because it's an amount of power that you can get from a branch circuit at home. Normal indoor LED lighting is almost a rounding error on your electricity bill these days. Daylight simulation uses much more power.
  - thrashh 4y ago
    But why would you compare when the goal is not to maximize your power usage before tripping a breaker. It is to get light.

zxcvbn4038 4y ago

The trick my local bar uses is to put artificial lights behind a stained glass window. No matter what time you go in it looks like late afternoon, about an hour before sunset. Unless you have a watch or line of sight to the outer door when someone opens it, you can’t tell what time it is. I’ve never seen behind the stained glass but am guessing they have warm light fluorescent bulbs (no heat) and something diffusing the light because it looks evenly distributed. There are no windows on the outside of the building so it seems something you can set into a wall.

ehnto 4y ago
Our casino takes a different approach, block all the sunlight so that no matter the time of day, the artificial light is the same.
- sokoloff 4y ago
  After a very long day playing poker, I walked into the Sky Ceiling area in the Venetian and had a really strong feeling that something was very wrong. (It was probably 2 AM, but the room is convincing enough to make it feel like late afternoon and the disconnect was strong enough that I had to leave the area.)

thrashh 4y ago

A lot of people barely notice poor CRI lights. Heck people will mix bulbs of different color temps and not even bat an eye. The issue is definitely the power usage. It’s not reasonable to dedicate that much power for the relatively minimal gain. Also, CRI is a relatively poor measurement of color quality because it measures a very desaturated color palette. You can have two high CRI lights and they will still not match. There are newer color rendering indices like TLCI, SSI and TM-30 to account for this.

atoav 4y ago
Good comment, thanks. Yeah you are right. I tried to simplify this as much as possible while still providing the gist of "various white light sources can have a different coverage of the light spectrum".
marvin 4y ago
Ultimatly, what matters is how the light spectrum looks. CRI is just an attempt at reducing that to a single number. Even then, many «daylight» scenes have very different light spectra.
- thrashh 4y ago
  While daylight definitely varies, I believe the spectra for the sun at noon at sea level is reasonably even and would be the main goal (as opposed to mimicking daylight in the morning or towards the arctic). CRI doesn’t measure vibrant red very well and human skin has that red.
scythe 4y ago
Wouldn't mixing bulbs at different colors improve the color rendering? Unless they're the same underlying substrates in different ratios (diode+phosphor), I guess, but I don't think they usually do that.
- deleted 4y ago
  [deleted]
4y ago

prox 4y ago

Do these lights also stimulate vitamine D production?

saalweachter 4y ago
UVB is what's required, I believe. 290 to 315 nm.
- rapjr9 4y ago
  Right, sunlight contains UVA and UVB and the UVB is what creates vitamin D. An indoor light that outputs UVB could be dangerous, the equivalent of laying outside in the sun all day, every day. It would also quickly degrade many materials in your house. UVA would trigger photosensitive eyeglasses turning them dark. Sperti makes a vitamin D lamp and it has a five minute timer and comes with UV blocking goggles (not sure what intensity it is relative to the sun) which suggests significant risk. So you may not want any forms of UV inside your home. Many windows these days have glass formulated to block UV to protect your rugs, drapes, and furniture. I'd question whether anyone would want the IR spectrum from an indoor sun-light also. I think what most people would want would be a high CRI light that has enough blue to trigger the brains time keeper. A bright indoor daylight-like light will make everything look very stark though (black shadows, objects brightly lit so you see all the fingerprints, scratches, and dust everywhere.) Your eyesight may degrade faster if you are constantly in brightly lit areas also. You may find that your autistic friends stop visiting you (or ask you to turn the lights off.) A lot of people who built A-frame houses with floor to ceiling windows at the end of the house found out that all that light entering 1) makes the house really hot 2) interferes with reading, watching TV, and using computers 3) fades their furniture and rugs. Even without the UV, bright indoor light has some issues, though it certainly can brighten dark spaces.

kodisha 4y ago

This made me think how little I actually think deeply about things. I read an OP question, and was like, meh there must be something out there. Then I read your answer, and was like, ohhhh this makes total sense. Of course you can't have equivalent of THE SUN for $50 and consuming couple of watts per day.

valenterry 4y ago

One thing about CRI is reflection though. When you use an LED with a high CRI then when it illumates your furniture, objects, people etc. it will look like as if the sun shines on it (in terms of colors). But what I would like to have is indirect light. E.g. point the lights to the ceiling and have the ceiling illumate the rest of the room. Not only is this less efficient in terms of electricty (but there isn't really a way around it) but it AFAIK also impacts the CRI depending on what material the ceiling/mat is made of. Any insights here?

sparker72678 4y ago
High quality glass diffusors so at least the light is more indirect?