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comment by snoodog
snoodog  ·  3051 days ago  ·  link  ·    ·  parent  ·  post: The L.E.D. Quandary: Why There’s No Such Thing as “Built to Last"

    I cannot handle your pugnacious idiocy today.

Uncalled for man. Im merely responding to the fancy LED fixtures that you linked that while they look amazing do no appear to have standard MR16s in them. A lot of the really cool ones have CREE XR-E or similar mounted on custom boards. While cool maintainability isnt all that great.

Here is the degradation curve of LEDs im guessing these are IDEAL curves based on perfect heat management. If you drive them hard in a hot environment its significantly worse.

Then there is the power-supply that always get omitted from the discussion. In order to drive the LED's correctly you have to have pretty clean DC power at a constant current. The circuitry for that isnt all that expensive but QC on many components is shit so its not uncommon to get flicker in LED's because there is a poorly rectified frequency in the output. Also these cheap components fail and when they do the whole thing becomes a paper weight.

Finally there is the whole color spectrum problem with LEDs. As im sure you are aware white LEDs are blue leds with a prizim so the color band is really narrow. Im surprised that doesn't cause you cinematography problems actually. For most application its not an issue but its worth considering. Personally i like the wide spectrum produced by Metal Halide but that's just me .

As for Livermore lights, they have their place in dark places like bars and certain coffee shops where you dont want to deal with fancy fixtures and its easier to put them in and get the ambiance you want than to do something else. Id never have them in my house though.





Devac  ·  3051 days ago  ·  link  ·  

    If you drive them hard in a hot environment its significantly worse.

Not all types of LED are so fragile. GaN LED show negligible decay even with heat-sink temperature at 105 degrees Celsius when compared to one whos heat-sink maintained 55 degrees Celsius. Yes, I know that this is just a recent research paper and not something available right now, but your point regarding temperature dependence might be much less significant in the near future when compared to current state.

snoodog  ·  3051 days ago  ·  link  ·  

Eventually maybe but my point is that at the moment the tech isnt quite there and LEDs are complex, finicky and difficult to drive correctly. The article says

    It is very challenging to grow high quality GaN on Si substrates because of the huge mis-

    match in the coefficient of thermal expansion

so im guessing that means were a decade out before they are affordable.

It took forever to get decent 3W leds out there into the market at a resonable price. Even now 100lm/watt LEDs are pricey.

kleinbl00  ·  3051 days ago  ·  link  ·  

I know. I'm sorry. My back is killing me, i'm on 5 nights of little sleep but you're still snarking at the margins to undermine my larger point and it's bullshit.

snoodog  ·  3051 days ago  ·  link  ·  

Sorry if it came off that way. The larger point im trying to make is that LED tech isn't always a great 1:1 replacement for incandescent and that doing LEDs correctly is darn hard. Both have their places and we shouldn't use LEDs as a replacement in all applications.

Also I wanted to mention that the entire advertised life of the bulb is unlikely to get realized. While the bulb has a theoretical life of 10k hours. It is unlikely to be realized due to the poor construction of the subcontinents, poor thermal management, and poor power rectification in the design. This is true for incandescents too but is much less of a problem when the bulbs are replaceable and $1 each.

My third point is that a lot of great tech dies at the margins for retrofit applications. Yeah LEDs might look great on street lights and are a good choice for new construction but once you factor in retrofit costs it may be cheaper to use the existing HPS bulbs in street light fixtures. LED fixtures need to be designed from the ground up and are sensitive to all sorts of factors that incandescent lights care little about therefore initial cost is high.

Also for cinematography purposes the LEDs may have a ripple flicker the really fucks up your shots so keep that in mind.

kleinbl00  ·  3051 days ago  ·  link  ·  

MY larger point is 1:1 replacement is pointless when I can whip out something the size of a Mars bar that puts out more light than my car's headlights.

For two hours.

Off a 3 hour USB charge.

And LEDs are cheap. They used to not be but they're getting stupid cheap. Especially when you factor in the power savings. Grow houses became effectively invisible once LED lights became viable. Los Angeles is saving $5 a year per streetlight. The switch cost is already paid for. So yeah - LEDs aren't bulletproof and they aren't magical but they absolutely, positively kick the shit out of incandescents for almost any application.

Yeah they suck ass for cinematography of any kind. The awesome part is in addition to the flicker the RGB ones have the same peaks as the CMOS most cameras use so they look all kinds of jacked.

But I ain't a cinematographer so no fucks given.