Overview of the types of dive lights.

[Dr. Lecter]

What colour temperature does your HID light generate?

R..

Since my old Salvo 21W was recently rebuilt by LM, including a new ballast and I put in a new bulb, I suspect the current LM 21W HID figure of 6500°K is correct.

---------- Post added May 14th, 2014 at 03:04 PM ----------

And it seems like DGX light is better than Light Monkey's that costs almost twice as much.

What led you to that conclusion about a NiMH-powered light with a 3 hour burn time? DGX's light is probably perfectly servicable, but LM's light is going to have better tech driving the LEDs and a much better battery (though there are aguments in favor of the old NiMH tech that DGX uses). The unsealed DGX battery is not going to be as flood-tolerant as the sealed LM LiPo, either.

 

[Diver0001]

Since my old Salvo 21W was recently rebuilt by LM, including a new ballast and I put in a new bulb, I suspect the current LM 21W HID figure of 6500°K is correct.

The Greenforce 21w LED generates 6300 according to their website. The angle is 10^o so if yours is generating say 1500 lumen @ 6^o or 7^o then your light might look brighter in poor visibility.

I really do get the impression, at least from this one line of lights, that the differences have become marginal over the last, say 5, years or so. Perhaps not all manufacturers have made a concerted effort to introduce the technology intelligently yet but LED, if it hasn't already caught up, is on the heels of HID and without all the ballast/ignition problems.

As I said above, I'm still using a HID head on my light but that's just because it still works and I don't see a need to replace it yet. My backup is LED though and my next primary lamp head will be an LED too.

YYMV etc. etc.

R..

 

[supergaijin]

I use the DRIS 1000. For the price ($90) it is an incredibly strong light and I heartily recommend it.
DRIS 1000

 

[HungoverDiver]

What led you to that conclusion about a NiMH-powered light with a 3 hour burn time? DGX's light is probably perfectly servicable, but LM's light is going to have better tech driving the LEDs and a much better battery (though there are aguments in favor of the old NiMH tech that DGX uses). The unsealed DGX battery is not going to be as flood-tolerant as the sealed LM LiPo, either.

Haha, see? That's why I'm asking! Ok so LM's light has got some magic battery?

 

[Diver0001]

Not all batteries are created equally. It's a matter of pros and cons.

LiPo batteries have a low internal resistance and continue to deliver stable voltage even when they're fairly heavly loaded. A NiMH battery can't do that. In human language that means that you'll have more joy with a brighter light head, or in colder water using a LiPo battery than a NiMH one. The down side to them is that you need some electronics to defend them from being deeply discharged, which means more design and engineering etc. NiMH batteries are much cheaper but less joy.

On one level you can say, "what works, works" so if the light with the cheaper battery does what you need it to do, then what's the problem? On the other hand, having a nice bright light that stays bright longer and stays bright in lower temperatures is nice.... is it twice the price nice? That's somewhat subjective.

R..

 

[victorzamora]

LED is more durable than HID, typically uses less power per light output than HID, but a focusable LED is harder to achieve and is less efficient than a focusable HID. HIDs typically have better "punch" through low-viz waters, due to their tighter beam angle. LED light heads are usually smaller than HID light heads, so there's less on your hand. Beam angle is the angle of the beam opening. A laser would have a beam angle of practically 0. A light bulb has a beam angle of nearly 360.

 

[HungoverDiver]

NiMH batteries are much cheaper but less joy.

LiPo = better battery
NiMH = cheaper battery

Got it. Thank you for the explanations between the two.

Beam angle is the angle of the beam opening. A laser would have a beam angle of practically 0. A light bulb has a beam angle of nearly 360.

Cool. That makes sense.


So what's this thing I've read about 6500°K. Light temperature? This is the temperature of daylight? That doesn't make sense...

 

[Diver0001]

So what's this thing I've read about 6500°K. Light temperature? This is the temperature of daylight? That doesn't make sense...

Think of it as a frequency. In music low frequencies make deep tones, high frequencies make high tones.

You can say the same about light in the visible spectrum but it's wavelengths instead of frequencies. You can see that light has different wavelengths from a rainbow. Red is lower, blue is higher. The "temperature" of the light has to do with the hue or the colour of it. That's not the whole story and I'm not a physicist so I don't know why they decided to express it in terms of a temperature, I just accept that they did.

What's important is what that temperature means. 6500^oK is about the same colour (wave length) as light coming from scattered sunlight at midday. For some reason light manufacturers decided that this particular colour is what people want. So that's what they normally aim for.

Lower temperatures tend more toward the yellow end of the scale (like an incandescent light bulb) and higher temperatures tend more toward the blue end of the scale, like those blue looking headlights you see on some German luxury cars.

R..

 

[HungoverDiver]

the blue end of the scale, like those blue looking headlights you see on some German luxury cars.

I hate those damn blue headlights! Too bright! I always think it's the police!

Thanks for the explanation. I read up a bit on wikipedia, and that was marginally informative.

 

[victorzamora]

The post I didn't get to finish should've also had: LED are getting MUCH better nowadays. Underwater Light Dude lights are far and away my favorite of any lights, and they're all LED. I have an HID and have dove many HID and many LED lights and have yet to find any light I'd prefer over an Underwater Light Dude light. His "biggest" primary has a 3500lm output at 30W, and his numbers are both conservative (actually a little less power and actually a little more light). HIDs start making a lot of sense above 30W, however I wouldn't trade my LED for ANY HID on the market, regardless of price.....just for the performance attributes specific to LED (absolute durability, lack of ballast, tiny head, and multiple power settings).

LED also has 10,000+ hour emmitter life, whereas lucky divers with good HID bulbs can't hit anywhere near that long of a life. AND LEDs can typically be used on land, which has come in handy while inspecting my house .

Lumens: There are many people much better versed on this than I, but I will tell you my issue with this. My issue is the manufacturers. Many manufacturers claim WAY more output than they really achieve. I've had a "claimed" 1000lm light next to a claimed 1800lm light next to a claimed 220lm light. Guess which light I take with me on all of my dives....the 220lm, as it is brighter AND more usable. Then I've seen claimed 1000lm lights that put out every bit as much light as a 21W HID, claiming to put out over 1500lm. The little LED was like a tenth the price of the HID, and less than a tenth the weight.

Lumens vs Lux: There are a couple (mainly one) light manufacturer claiming performance in Lux. The problem? Unless all the lights are tested on the same rig, on the same box, on the same day, under the same conditions, under identical circumstances, there's no way of truly measuring lux. UWLD made a light box for testing their lights and offered Lux meter testing to all other light manufacturers, just to see what happened. No mfg sent their lights in, even the one claiming that lux was more important in every aspect than lumens. So, while lux is a theoretically better metric by which to compare lights....there's no standard in lux measurements.

As for which to get......you can go two ways, in my opinion. Super cheap or super nice. I got a $100 used HID canister. The light is great, but the canister is huge and the batteries are very ghetto (my own design, with a charger that half works). The DGX is a great option for a cheap, new, retail light. There are a few people that sell cheap "homebuilt" canisters that seem to have great performance for the price. That way, you can figure out what you want and what you want to do and if you "need" a better light. Then your cheap one can become your backup. OR, you go to the absolute top of the line. Then you only have two decisions to make: "HID or LED?", and then "How big?"

If HID, don't get anything that's not a Light Monkey. If LED, don't get anything that's not UWLD. Don't compare them, they're apples and oranges. Compare HID vs LED and pick which you like best. Then pick the biggest light you [-]think you might need[/-] can afford, and be happy for a LONG time to come.