Replacing Xenon headlights

[nitely]

[QUOTE=Phatty McPatty;186773]Yes, 6,500k is considered daylight, just as much as 3,000k and everything in between (sunrise, sunset, noonday, cloudy, foggy -- they're all considered daylight; and all have very different "white" hues). Daylight is as vaguely defined as "warm" or "best" or for this argument, "white" or "bright". As njjoe said, it's all relative. Speaking of bright, don't confuse color temperature with brightness. 6500k is not "the brightest" anything; it's simply a specific measurement of white light.


I meant whitest daylight available--seems like people are trying to get to as close to a white light as possible and veering away from the yellowish/traditional spectrum.




Sure, that's because blue light has a higher frequency than green and red light. But what does that have to do with human sight and safe road illumination? To the human eye, intense blue light equates to intense glare. Have you ever driven by a police car at night with flashing blue LEDs? It's downright disorienting because intense bluish light quickly overloads your vision; ie glare.

Just to point out that above this temp its not as useful to the human eye specially in driving which some people seem to think.



There is no such thing as a 50-watt ballast or 50-watt HID bulb in the automotive world.

Just giving a comparison that higher wattage ballast and bulb will give you better coverage. Not yet delve into the auto world HID bulb availability.



Actually you can -- that's what a "50-watt HID kit" is. It's an over-driven 35-watt ballast and bulb. You're right though, their lifespan is greatly decreased by the increased voltage.

That does not make sense at all. Why use it if you'll burn it real fast. That does not sound a viable application to me. What do you mean over driven 35 ballast and bulb? If its ballast has bigger wattage than the bulb, then they are doing it wrong already.

I have dealt with HIDs---metal halides in my 180g reef tank for 15+ years trying to mimic natural daylight in the reef and making the live sps corals aesthetically pleasing to the eye. Have seen how the bulb industry improve/change to give the whitest possible daylight bulbs you can get. Which seems to be the trend. Anyways, I do have a little understanding on the matter. HID bulbs color temp also drops after so many hours of burning. Once you have the 6500K color later you drop to 4000k color which reef aquarist hates--everything gets yellowish. So we end up changing bulb even before it burns out. Supplement of the blue/actinic O3 light bulb is also used.

[Phatty McPatty]

Originally Posted by nitely

I meant whitest daylight available--seems like people are trying to get to as close to a white light as possible and veering away from the yellowish/traditional spectrum.

I don't know why! Actually, I do -- hype, bling, skewed / misunderstood data and of course the consumer masses drinking the kool-aid offered by persuasive advertisers.

Originally Posted by nitely

Just to point out that above this temp its not as useful to the human eye specially in driving which some people seem to think.

Very true.

Originally Posted by nitely

That does not make sense at all. Why use it if you'll burn it real fast. That does not sound a viable application to me. What do you mean over driven 35 ballast and bulb? If its ballast has bigger wattage than the bulb, then they are doing it wrong already.

You're preaching to the choir my friend. If that's what you're arguing, then it seems we're arguing the same point! Over-driving HID bulbs is achieved by using a capacitor with a rating too high for the fixture. Although light output may increase, the excess wattage dramatically increases operating temperatures of electrodes, arc tubes and bulb walls. The arc tube may bulge and possibly shatter. Lumen maintenance and lamp life also are significantly decreased.

Originally Posted by nitely

I have dealt with HIDs---metal halides in my 180g reef tank for 15+ years trying to mimic natural daylight in the reef and making the live sps corals aesthetically pleasing to the eye. Have seen how the bulb industry improve/change to give the whitest possible daylight bulbs you can get. Which seems to be the trend. Anyways, I do have a little understanding on the matter. HID bulbs color temp also drops after so many hours of burning. Once you have the 6500K color later you drop to 4000k color which reef aquarist hates--everything gets yellowish. So we end up changing bulb even before it burns out. Supplement of the blue/actinic O3 light bulb is also used.

I haven't seen data to support that. During the lifespan of the bulb, the electrode material evaporates and deposits itself onto the inner surface of the arc tube, which results in darkening and overheating of the arc tube. As the gap between the electrodes increase, the output characteristics change (the CCT shifts upwards). Do you know what brand of bulb you're using? I've read that Osram-Sylvania bulbs tend to turn pinkish rather than bluish.

Originally Posted by njjoe

Unfortunately, this debate is never-ending.

Yeah. But this forum tends to be well-informed -- unique in the automotive forum world. Since I know much more about the lighting world than I do of the mechanics of the MO, it makes most sense to contribute to this topic (even though I know that the facts are unpopular). I hope the data I provide will enlighten at least a few members.

[nitely]

Originally Posted by Phatty McPatty

I haven't seen data to support that. During the lifespan of the bulb, the electrode material evaporates and deposits itself onto the inner surface of the arc tube, which results in darkening and overheating of the arc tube. As the gap between the electrodes increase, the output characteristics change (the CCT shifts upwards). Do you know what brand of bulb you're using? I've read that Osram-Sylvania bulbs tend to turn pinkish rather than bluish..

I've seen it first hand. On a 5500K 175 watt mogul base venture bulb. When you replace the old with the new you can readily tell that the new is a bit whiter than the old-yellower. Color of Light I have also used 6500K iwasaki for a couple of years which was a little improvement from the 5500Ks. This was the only available metal halide during the late 80s to mid 90s. Later came higher wattage halides with more color temp choices--demanded by the reef aquarium industry. I use the ushio 10000K 250 watt bulb mogul base the longest. My set up was 4 of these bad boys over the 2' X 6'X 2' tank. 1000 watts of light beaming down my frags and green staghorn on a 12 hour day schedule. Man! they sure were happy. My electric bill on the other hand was a different story. I also tried the 250 watt 13000K double ended bulb by aqualine AB. you need a uv shield to run those. BTW, in reef aquarium industry, osram/sylvania is at the bottom of the list. The general idea is to give the corals the beneficial blue spectrum without lookin psychedelic and at the same time giving the whitest possible light to see the coral on its proper natural color. That falls between the 10000K 13000K range bulb which the majority likes to use.

[Phatty McPatty]

Ok, I see the discrepancy. I'm talking about metal-halide lamps with xenon gas, you're talking about metal-halide lamps with argon gas. They're similar in that they are both arc lighting, but have different lighting characteristics due to having different fill gases. I think we're on the same page now!