Advice on dive lights for my advanced course

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I'm not a fan of the D26 only because finding quality 26650 batteries is very difficult. I refuse to allow any battery with "fire" in the name in my house or anywhere near anything important, and there aren't a lot of 26650's out there without "fire" in the name.
I'll stick to 18650's and know that i'm using quality cells and sacrifice some burn time. An hour on high is more than enough for most diving and anything that I need significantly more burn time for will use a canister
 
Just saw this one for 30 bucks with the batteries. It's similar to the ones on Amazon and although it says 800 lumens it has the same Cree light announced as 1000 lumens on other lights.

I bought that same light (different brand markings, but same light) on Amazon for under $25. It's good. Two of those and the batteries/charger tbone suggested are what I use in cave diving and I like them a lot.
 
I'm not a fan of the D26 only because finding quality 26650 batteries is very difficult. I refuse to allow any battery with "fire" in the name in my house or anywhere near anything important, and there aren't a lot of 26650's out there without "fire" in the name.
I'll stick to 18650's and know that i'm using quality cells and sacrifice some burn time. An hour on high is more than enough for most diving and anything that I need significantly more burn time for will use a canister

Soshine 5500mAh 26650 batteries are abundant on eBay. And cheap. Around $25 for 4. Mine have tested around 5300mAh in my Opus charger/tester. I got them at the beginning of last July and they still work just fine.

I just ordered some more today for my new video lights.

4x Soshine 5500mAh 3.7V 26650 Li-ion Rechargeable Battery PCB Protection US G5I3 | eBay

I'll test these when they arrive to make sure they are also good.
 
I'm about to start my advanced adventurer course and need to buy a primary and backup light.
Why? Night dive? Wreck dive? Not needed for most of the adventure dives.....
 
"Lumen" ratings are usually deceptive. Unless they state "## lumens over ## square feet at a distance of ## feet" they mean nothing, because lumens refer to how much light is falling on a specific area--not the overall light output.

So if your light, held ten feet away from a wall, makes a nice bright circle that is two feet wide, and my light makes a circle that is three feet wide, same appearance? Then my light would need to be rated roughly twice as many lumens as yours. But, to the eye (or meter) THEY ARE EQUALLY BRIGHT. The difference is in how tightly they are focused. A lot of the cheap lights have high lumen ratings--because they are pinpoint lights, they do not cast a wide beam.

FWIW.

Wasn't it the Talking Heads who sang "They Blinded Me With Science!" ? Yeah, that's lumens.
 
@Rred lumens you kind of talked yourself in a circle there.... Lux is deceptive, lumen is fixed. lux ratings can be skewed by having a tight beam angle, see halcyon, but total lumen output is not able to change.

lux is what you are talking about, which is lumens per unit area measured at a distance. Lux is very deceptive because of the example you gave. The issue there is that the 3ft circle might be more useful for what you are doing.

Perfect example is in cave diving. Halcyon and Dive Rite love to talk about lux instead of lumen because their lights are severely lacking in the lumen department at around 800 lumen each *same as a backup light*, but they have more useful light because of having much tighter beam angles. Conversely, UWLD has a wider beam angle at 8* instead of 6*, but they can put out 4+ x as much light, so the lux numbers are still higher, but the useful light is also considerably higher. Halcyon puts a very tight spot in the middle of their light to crank their lux numbers up, but the spill is pretty weak so it's great for signalling, but not a whole lot else. Great source of tunnel vision.

If we look at the image below, the most similar comparison would be done with the UWLD LD-15 and the Light Monkey 21w HID. They are throwing a similar lumen output of 1300-1500 lumen, but the 21w HID has a tighter beam angle so it has more lux. Notice how much more area around the hot spot is illuminated and how much more you can see. Sure the hot spot is light up brilliantly, and it could punch a hole through granite, but is it useful? I'd argue it isn't. Lux is important, but because the readings can be so variable *a single mm of movement can throw the lux readings all over the place*, having a total light output against a beam angle is a much more useful comparison for lights.

Key-Frame-2.png

image taken from this link, which has the videos that are important to watch as well
Beam Comparison

your comment about the cheap lights is actually backwards because Lumen can't change so I think you may have talked yourself in a circle.
Halcyon Focus and Flare - Halcyon Dive Systems
Looking at Halcyons site, the exact same emitter is able to produce 11,500 lux on the flare, but go all the way up to 39,300 lux on the Focus. The Focus is able to get the beam angle so tight that it basically tricks the lux meter because the meter is not measuring a large area, only the small bit in the center. Both are 710 lumen. Beam angle can't change the lumen rating, only the lux rating. It can change useful lumens, but since LED's are forward facing emitters, it is essentially all useful lumens vs. something like an HID which is a side emitter and may have non useful lumens if it isn't focused properly.

No one that I know of measures lux with large enough of a sensor to make it a useful measurement which is why I don't know of any dedicated manufacturers of dive lights that use them despite Halcyon claiming it's the industry standard. I only know of them and Dive Rite that use them, everyone else used just wattage in the HID and Halogen era *and Light Monkey still does unfortunately, though that's to hide a lot of other issues with their LED's*, and everyone else uses lumens and beam angle since it's a better way to compare lights.

one word of warning though, most manufacturers are quoting lumen behind the lens because the equipment to test lumens is horrifically expensive, so expect to see up to 20% drop in lumens in the front of the glass in the real world. Thankfully since most everyone quotes behind the glass, it's at least on the same page. Also important to note, there are many manufacturers, with Big Blue being the largest offender, that quotes some pie in the sky theoretical lumen number but can't actually achieve it, and if they do, it is only for a minute or two because they are not using constant output drivers. After about 30 minutes, the Big Blue lights drop to roughly 30% of their claimed lumen output and will maintain that for the rest of their burn. They only achieve about 80% of their claimed lumen output but it is essentially a linear drop from 80% to 30% in the first 30 minutes of their burn. Most of the high end lights do not exhibit this behavior, Halcyon, Dive Rite, Light Monkey, UWLD, etc. so just be mindful when you purchase a light from Big Blue and a bunch of other budget manufacturers, that you should factor that into your purchase
 
Thanks, tbone. And I suppose if we really wanted to pick a part lights...they "overamp" the LEDs, the same way that dive lights use to overvolt conventional filament bulbs, to get more brightness out of them. Without discussing how that can radically affect LED life.

I think it is Underwater Kinetics ? that has some kind of thermal sensor in the light, an aluminum bit that comes through the front lens and senses whether the lamp is being cooled (by water) or used in the air, where the LED would have to be throttled back a bit.
 
Thanks, tbone. And I suppose if we really wanted to pick a part lights...they "overamp" the LEDs, the same way that dive lights use to overvolt conventional filament bulbs, to get more brightness out of them. Without discussing how that can radically affect LED life.

I think it is Underwater Kinetics ? that has some kind of thermal sensor in the light, an aluminum bit that comes through the front lens and senses whether the lamp is being cooled (by water) or used in the air, where the LED would have to be throttled back a bit.

the high quality LED drivers will have temperature sensors on the boards that will kick down their brightness if they start to overheat.

overdriving the LED's is well within spec and is a sacrifice over their idiotically long life span for light output. Not something they would have to publish, but I don't know of anyone off the top of my head who is overdriving the XML's.
 
I don't know any names either, but considering the way that so much stuff comes out of China with "Genuine CREE", when CREE doesn't seem to be aware of that production, and the way that so many LED lights in general seem to have lives very much shorter than the 50,000 hour norms, I wouldn't be surprised. Of course compared to mattress companies, all the dive light & equipment makers are upright, honest, and trustworthy.(G)
 

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