@dapperdanman Well retro-reflective surface don't perfectly return light, they just return a main cone back, and a few fainter cones in stranger anglers. If the incoming light is somewhat collimated, both cones could maybe cancel a bit.
@pancooks sounds like a good find. I notice some of the Ali sellers also sell a variety of other brightness enhancement films that are significantly cheaper - unsure how their performance compares.
Do you have any sources for larger sheets? I'm looking to cover approx 0.6mx1m. Also curious how you are mounting them
@dapperdanman When I was looking I concluded the difference in the 3M and the other ones are that the 3M is dual layer / both X and Y prisms stacked together, and the other ones are just a single layer.
I haven't found any good sources for larger sheets. I've been using the 30cm wide rolls in 120x30cm light boxes, with an additional two layers of the milky screen printing film to separate the 4500K light source into 4000K (for the direct light) and 5000k (for the scattered light). Looks quite natural!
I haven't yet found a good way of mounting the film, simply putting it in the film stack of the LED panels I'm using, but it bulges a bit if I accidentally bend the flimsy panel when moving it. Not ideal.
I'm planning a ceiling mounted mirror bounced ETC Source Four as another experiment, where I plan to place the film (just the scattering film) in a glass sandwich. I'll post an update on how that works out.
@pancooks sounds like the 3M is maybe worth springing for then, even if it's a bit pricey. Do you notice the light projecting more into the room when you use it?
I also have some LGT075J diffusion film I was going to use, maybe I'll run an additional layer of brightness enhancement film over the top. The diffusion film already has a light transmission of only 60% or so, so I'm keen not to lose too much additional light. Diffusing light efficiently (high transmission) seems to be a harder problem than I originally thought.
I was going to clamp the film in at the edges of the wooden frame with some aluminium strip. Not sure yet how well that will work.
Would love to see some photos of your setup if you get the chance. I'll also post some of my work in progress.
@dapperdanman Yeah, it throws light well! Here's a comparison I made of one of the 120x30cm panels aimed at the ceiling with and without the 3M BEF film:
A problem I did run into is that I have quite a large living room + kitchen space, and illuminating it with 120x30cm panels very realistically makes it look like I have a huge space with only a couple of tiny windows, even though the light coming from it is quite pleasant. (In the panels I'm using 98+ CRI Seoul Semiconductor LED strips.)
I haven't found a way around that yet, and am only using them in my smaller bedroom at the moment. Regarding the light loss, I ended up running mine at half the max brightness, as too much light with too little surface area was quite blinding. I'm now still running them at around 150W/m². I'm hoping to make a projection based artificial sun for the living room later, working with mirrors to increase the effective surface area, as I feel more surface area is my next point of improvement.
The LED head I bought also costed 220 euros (Nanlite Forza 60B) and has a CCT range from 2700K to 6500K.
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I agree that the use of a finished light source (heat sink, fan, color and brightness adjustment) and projection lenses make the light generation much simpler and i also wonder if building this myself is that much cheaper. I found the rollei (called colbor in other regions of the world) candela 60W or 100W bi-color with a optical spot to be even more affordable.
But there is one caveat with these - how do you control the light color during the day? Yes, there are apps an you can do it via bluetooth from the app. But how do you automate the light changing during a day (and maybe also switching off the light when no one is there as it consumes quiet some power)?
I think the standard in the video lighting is DMX but then again we are talking about a different price range. This might warant doing your own led controller and maybe only re-use the housing and optics of the professional studio lights.
I found this one that has DMX, is only 40W, but has 3 lenses for 5°, 10° or 25° based on distance to mirror: https://www.thomann.de/de/cameo_q_spot_40_tw_black.htm . It can be remotely (e.g. from home assistant) dimmed and can also change its color during the day.
I guess what we are looking for is a "spot" with possibility to change the temperature of the white. The differences in "hard" light modifiers is explained nicely here:
UPDATE: I checked and the 4.5° angle cannot really be changed (it looks like its using a 3D Fresnell lense) and only diffusors can be added that do not provide a sharp frame. So i guess this only works if you have a lot of distance between this thing and the window that you want to shine through. Back to the "classic" permanent lights with optical projector mount from rollei or nanlite.
FINAL UPDATE: I found something that sets you back only 100€: The 40W ULANZI or M60 device is 50 and the optical lens in front to allow to collumate it and become a "spot" or "beam" instead of a "wash" is just another 50€. It certainly is not the quality of the nanlite setup but its a lot cheaper to product the light we need. Key question is still the angle it puts out. But as it can project gobos it should be more around the 10-15° that i think are good for our case. Here is the link - the last option is the optical lense with a mini bowers mount: https://de.aliexpress.com/item/1005006756448852.html?spm=a2g0o.cart.0.0.39994ae4GPaBqn&mp=1&gatewayAdapt=glo2deu
FINAL FINAL UPDATE FOR TODAY: Last option with bi-color that is from a trusted manufacturer and combines the 30W LED with a movable lens. Its not the same sharp light compared to a projection mount but its probably good enough. https://www.smallrig.com/de/RC-30B-COB-LED-Video-Light.html
This post was modified 4 months ago 4 times by marcusbehrens
@bigfield How do your project go? We have a room with no windows which could do with similar treatment so I'm interested in how it went!
I noticed that the Circadian Sky produces an impressive 2,200-40,000k while the LEDstore 300x1200 is a more typical 2900K-5500K. I think that might be less range than my hue bulbs. I use Home Assistant with Adaptive Lighting so our lights are white during the day and warm in the evening - I'd use that for this panel too
This post was modified 3 months ago 2 times by adz74
So as I'm following this thread I wanted to make a summary of the artificial sun possibilities.
Am I correct there are 4 versions mentioned in this thread?
1. simple version
a led inside a white box with a fresnel lens sheet covered with waterproof inkjet foil
(you could stack multiple boxes to get a larger panel)
2. mirror version
a led with a small fresnel lens projecting up to a mirror that is covered with waterproof inkjet foil
3. satellite dish version
a led projecting on a parabolic reflective dish that reflects the light back through waterproof inkjet foil window
4. more complex setups
using multiple parabolic mirrors and stuff, not getting into those 🙂
I'm going with the satellite dish version because I have windows in my basement studio with available space behind them to put the dishes (see pics in attachment). But I have some questions:
1. Is every satellite dish a perfect parabolic shape? This is very important to get perfect collimated light rays (parallel light rays) to get the infinity light effect, correct? I would need an off axis satellite dish so I can place the led in a higher position in front of the dish. Also an oval shape would be best because it could cover 2 windows. But these are harder to find.
2. What is the best reflective foil to put on the dish? Here are some links from the thread:
5. There is also the idea of a parabolic trough (easier to make and can be used with a led strip)
But the light collimation only happens in 1 axis, is this really noticeable and does it produce 'lower quality' sunlight compared to a parabolic dish?
6. The blue sky effect (Raleigh scattering /Tyndall effect) options: what is the best quality? I will go with the waterproof inkjet foil, but maybe there is a real winner for the most convincing daylight effect?
1 soap water: do you have to replace the water often?
2 soap water with jellyfying agent?
3 mixing colloidal silica in epoxy
4 waterproof inkjet foil (multiple layers)
7. What led type is the best to use for an artificial sun that can also be dimmed and tuned in color (to make it more orange to emulate evening sunset light). I understand the CRI must be high enough!
1 single color led: is this always the brightest option?
2 bi color led: we can change the CCT and make it more orange to the emulate sunset evening light
3 rgb led: they can do all colors, but are they bright enough and have a good CRI value?
And what's the best intensity to use? My room is large (100 square meters) but I have 2 blocks of 4 windows each where I could place multiple dishes. So I guess if I would use 4 dishes of 200watt each it would be very bright in there?
8. What about pre made led studio lights? Here's some links from the thread:
For my purpose (the basement studio) the buttons need to be on the inside of the window to be able to adjust the CCT and dimming without having to open the window to get to the led. Maybe I could take them apart and modify them to put the controls inside my room? Cool stuff here is things like effects, dmx control, timed hue changes, ... There's also mention of cheap led headlights?
9. Led cooling: since I have a lot of space behind the windows I could maybe use a very big aluminium heatsink so I wouldn't need fans? I would have space to put a 3 meter long aluminium bar in the space behind the windows.. But maybe this will block a lot of light coming back from the dish?
I attached a picture of my studio windows, there are 2 blocks of 4 windows.
Sorry for the many questions and for repeating a lot of stuff that has been written here already..
Thanks!
This post was modified 3 months ago 2 times by johnnydub
Could we manipulate the spectrum of artificial sunlight to mimic the effects of a sunrise or sunset indoors, potentially affecting our circadian rhythms and sleep patterns?
First time posting here, but I've been reading this thread for about 2 years now 😆 I've been working on a project very much inspired by the original video and this forum thread, and I've finally blogged about it:
Here are some quick pictures, but I go into much more detail in my blog post. Thank you @DIYperks for making a video that has inspired me to work really hard on this project and learn so many things along the way. Thank you to everyone who posted their progress in this thread over the years. I'm happy that I finally get to do the same myself and report on my progress.
Cheers to this community, and long live artificial sunlight projects!
Official Brand Store, diyledu-home.com Our Tik tok account, @diyleduhome Our Tik tok store, https://www.tiktok.com/@diyleduhome
Aliexpress store, https://diyledu-home520.aliexpress.com/store/1101410436
Ebay store, https://www.ebay.com/usr/joy-street, or https://www.ebay.com/str/indeedstore01
Building an artificial sun is an incredible idea, and you're right that optics are a big part of getting it right. If the program you found helps with light modeling or spectrum analysis, it could be a valuable tool for all of us.
I’ve read one article that mentioned the difference between full-spectrum and red-blue spectrum lighting—mainly that full-spectrum mimics natural sunlight and supports a wider range of plant processes, while red-blue is more energy-efficient and targets photosynthesis directly. But I’m not sure I fully understand the trade-offs. When designing your artificial sun, are you aiming for a full-spectrum output or focusing more on red-blue wavelengths for plant growth? What are your thoughts?
Yes, the program does help with light simulation. I'm still deciding between full-spectrum and red-blue—full-spectrum seems better for all-around plant health, but red-blue is tempting for efficiency. Maybe a mix of both is the best option?
