Mine is mapping. I am a big OpenStreetMap contributor and I have mapped many towns near me that were previously completely unmapped.
Mine is mapping. I am a big OpenStreetMap contributor and I have mapped many towns near me that were previously completely unmapped.
My most stereotypical special interest (in that it’s something really random that you might assume there’s not a lot of depth to) is artificial lighting technology.
But I have a lot of stuff I could infodump about: computers, video games, TTRPGs, world building, neurology, etc.
One of my daughter’s old classmates is currently studying the effects of artificial lighting from port cities on local sea creatures - how it affects their day/night cycle - that’s the gist I got anyway.
I have a question for you that I’ve not been able to get answer to by normal googling or asking the GPTs.
I need to focus light from cinema projectors using camera lenses. As you might be aware, projectors may use lamp or LED as their primary light source. The former used more wattage for producing same lumens of light.
My question is: if I choose two projectors of each type that give out same lumens of light and I focus all of it with my lens, will one of them heat up my lens more than the other? I’m other words I’m just talking about the heat perception of light of equal intensity from the two sources and not how much heat is generated in creating them, if that makes any sense.
Thanks!
It kinda depends on my much IR light your camera lens absorbs.
A certain percentage of the light produced by the lamp (whether it’s incandescent or an arc lamp) is infrared light. This is the same as the radiant heat you can feel coming off of a fire, for example.
Whereas with the LED light almost all of the photons it’s emitting are going to be in the visible band. High intensity LEDs do produce some amount of waste heat, but this is in the form of heating up the structure they’re connected to. So not only do they waste less energy, the energy they do waste isn’t shooting out the front in the form of IR.
To be clear, visible light also turns into heat when it’s absorbed, but with the LED you’d just be shooting visible light through your lens, whereas with a lamp you’d be shooting the same amount of visible light (same lumen value) plus a bunch of IR. So in the latter case there’s a greater total amount of energy flowing through the lens.
All of this is to say that an LED emitter of the same lumen value of almost certainly has less of a potential to heat up your camera lens. I guess if IR just passed right through it (and none of it got absorbed in the glass or in the tube of the lens) then it might not be much of a problem, and you’d just be heating up your projection screen slightly more. But I don’t know enough about camera lenses to say if that’s the case.
Thank you so very much! This makes sense and answers my question perfectly.
Have you seen the technology connections videos on lighting? The one about the Balafire is interesting, and he also recently discovered some excellent Christmas lights.
I have, I like his channel a lot.
Could you tell me some cool stuff about artificial lighting technologies? That sounds interesting!
Probably the weirdest kind of lightbulb I’ve heard of is the electron stimulated luminescence bulb.
They were basically little CRT screens that produced white light instead of a picture. They had about the same efficiency and lifespan as CFL bulbs (which were around at the same time) but better color rendering capability (higher CRI). They also didn’t use mercury in their construction.
They never caught on probably because of how bulky they were, with cost probably being a factor as well (though if they were as manufactured at the scales CFLs were the cost may have come down). Today LEDs are better than both of course.
Speaking of cost and LEDs, it’s pretty remarkable just how cheap lighting has gotten. Consider this article, where they talk about the cost of producing light with candles vs with incandescent bulbs. But since 2006 we have developed some LED bulbs that approach or exceed 200 lumens per watt. That’s a more than 11x improvement over the 17 lumens per watt figure given in that article. That adds another .9 to the percentage cost drop before we even consider the longer lifetime of the LED bulb.
I think I calculated at some point that Philips Ultra Efficient bulbs cost less than $1 per year per bulb to operate if you add the cost of power + the purchase price of the bulb amortized over its lifetime. At this point lighting up a room is almost free.