Lumens for primary?

[kwinter]

Going back to the original post, there are some things to point out.

1. Lumens vs lux. This is a very tough one because it isn't as simple as I'm going to present it, and most manufacturers do not list lux. If you could somehow capture all of the light coming out of the lighthead, that is a measure of lumens. But it has nothing to do with how much light hits a target in front of you. Lux is the more appropriate measure of "brightness" of a light. One lux is equal to one lumen per square meter. So if you are aiming a light 2 meters in front of you at a bullseye, lux is a measure of how much light actually hits that bullseye. It takes into account the spread of the light beam as well as the "penetration" of the light. Very few manufacturers list lux measurements. And, as has been clearly stated by others, many manufacturers grossly overstate their measure of lumens.

2. Penetration. Many people feel strongly that HID has more "punch" through murky water than LED. LED technology is improving at a ridiculous pace, but if your diving will mostly be in particulate loaded water, you might consider the claims of HID being superior. There are disadvantages as well, including lifespan and cost of replacement bulbs, and the larger size of the lightheads.

3. The need for a canister. Many folks are eschewing the traditional wired canister as the freestanding LED lights offer more and more burn time. And as others have pointed out, it can be cheaper and more reliable to buy several standalone lights instead of one wired canister light. Of course the cheaper Chinese made canister lights like the Brinyte bring the cost of a long burning bright light down to a very reasonable cost.

Just some thoughts about the initial question. You've received some great advice so far. But take anything your instructor tells you with a grain of salt. He might have an agenda toward a traditional wired canister from one of the established companies because that's the way things have been for a long time. Just keep in mind that the times they are a changing. I'm looking forward to seeing what Chris has done with the Deep Six stuff.

 

[stuartv]

Nobody seems to, as yet, directly addressed my question about the possibility of a really bright light actually making it harder to see very far in turbid water. Does it just not work out that way?

 

[buddhasummer]

Nobody seems to, as yet, directly addressed my question about the possibility of a really bright light actually making it harder to see very far in turbid water. Does it just not work out that way?

Not sure I understand exactly what info you are looking for but it depends on beam angle, a tighter beam will punch through murk, a wider beam will make it harder to see, think high beams in fog, as the light bounces back off the particulate. Obviously a high output tight beam will work better that a low output tight beam, or a high output wide beam. So to "directly" address your question, no I don't think a really bright light will make it harder to see very far in turbid water assuming tight beam angle.

 

[stuartv]

That's exactly what I'm talking about. I even used the high beam-in-fog example earlier in this thread when I asked this question.

High beams in fog make it harder to see. So, if I have a choice of a really bright 8 degree beam or a less bright 8 degree beam, in turbid water, is the really bright beam going to create more glare from the backscatter and actually make it harder to see?

 

[bradells]

That's exactly what I'm talking about. I even used the high beam-in-fog example earlier in this thread when I asked this question. High beams in fog make it harder to see. So, if I have a choice of a really bright 8 degree beam or a less bright 8 degree beam, in turbid water, is the really bright beam going to create more glare from the backscatter and actually make it harder to see?

Yes and no. In a car, the lights are fixed and pointed directly infront of you, creating a 'harder to see experience.'

This is similar to Backscatter.

With a handheld light, your pointing it not directly infront of you, so that glare and such isn't an issue, and you can see farther because of it.

But giant chunks of snot, silt and debris will kill any light penetration.


BRad

 

[Dirty-Dog]

That's exactly what I'm talking about. I even used the high beam-in-fog example earlier in this thread when I asked this question.

High beams in fog make it harder to see. So, if I have a choice of a really bright 8 degree beam or a less bright 8 degree beam, in turbid water, is the really bright beam going to create more glare from the backscatter and actually make it harder to see?

Particulate matter in the water is not likely to be reflective like fog or snow.

I've been in an unmapped cenote with calcine flakes falling from the ceiling (because of our bubbles hitting them), and while it looked like it was snowing, the flakes were not reflective and didn't cause the sort of glare high beams from a car would.

 

[eelnoraa]

Nobody seems to, as yet, directly addressed my question about the possibility of a really bright light actually making it harder to see very far in turbid water. Does it just not work out that way?

That's exactly what I'm talking about. I even used the high beam-in-fog example earlier in this thread when I asked this question.

High beams in fog make it harder to see. So, if I have a choice of a really bright 8 degree beam or a less bright 8 degree beam, in turbid water, is the really bright beam going to create more glare from the backscatter and actually make it harder to see?

The reason no one address your question is because your question is so focus on one single combination of corner cases, which is usually a low priority for most diver.

The general answer from me is that if you have a brighter light, you will be able to see better even in relatively low viz water. Now, if you are diving in zero viz water most of the time, then a 8 degree LED is probably the wrong light for the job to begin with. You will be better off with a HID.

I would still say more light is better in general for two reasons: 1)ambiemt light matters, the higher the ambient light, the less visible your light beam is. So you want more light. 2)half, if not more, of the whole purpose to have a light in tech diving is for others to see you. I have use 21W HID and 35W HID side by side. I do like 35W better in 5ft viz water. However, 35W come at cost of bulkier battery and/or shorter run time. So I ended up selling the 35W.

The thing is choice of gear is very personal. You don't need to justify a lower output light because it works better in low viz water. If that is what you need and you are happy with it, look no further. Now if that is not what you want, no amount of justification from us can make you happy. We made suggestion based on your initial post, where you stated you don't want to buy twice. And in the path of technical training and diving, $1000 is really peanuts in the grand scheme. That is why we suggested one of the proven lights.

If cost is an issue at this moment, I would even suggest start your tech training with something like DGX600 backup if your course allow it. If not, borrow a light from your instructor for the class. After you have some experience with a canister light, you will be able to make better judgement of what you need.

 

[tbone1004]

I'll echo above. You really have 2 choices in primary canister lights right now.
UWLD-35 with the big battery. $1750
LM 21/35 HID-$1300-$1900 depending on preference.

LM just doesn't have the same quality LED as the UWLD, and the UWLD has the switch on the head, which is a HUGE feature especially in sidemount, but even in backmount if you have any stages/deco bottles on the right side flipping that switch can be cumbersome. LM still makes great HID's, but you need to evaluate if you really need/want an HID.

Your question about more light is "it depends", just because two lights have an 8* beam doesn't mean that they have the same corona, the corona is what will make or break the backscatter. The UWLD comes with 3 settings so you can just tap the light head and reduce output. HID's are fixed. If you do video, the HID is basically unusable with a fixed beam pattern because it will create a wicked hotspot, but that same hot spot will allow you to signal in OW better.

Dive Rite is convinced that canisters aren't going to be needed with upcoming battery technologies for "normal" diving. Also remember where we came from, 10w HID's were the standard for a very long time and your little backup lights put out a similar light output to the 10w HID's. If they were good enough 5 years ago, they should still be good now as long as your buddy isn't blowing you out of the water. I use a LD15, my buddy has a LD35, I have to be in front because I can't signal him in a cave if his light is on high. Personal preference, but for what I do, I don't see the need for any more light until I upgrade to the LD-60V for video. In the ocean I use little backup lights because they are tiny, cheap, and takes a cord out of the way. I would recommend the same unless you need the extra burn time, which you won't for a while since you won't have your light on after you start ascent, or you want more light. Not need, want more light.

 

[Lorenzoid]

Used 21W HID lights seem to come up for sale on a regular basis. There may be "better" available, but 21 W HID is a solid choice that nobody can seriously criticize. I got one this way. If I end up buying newer technology in five years, so be it.

 

[Tony387]

I dive with a 10W DR HID light and I love it. I dive almost exclusively in low viz texas lakes and it works like a champ, during the day as well as at night. It's beam really cuts through murky water. As someone else already mentioned, you can pick them up for a good price ($250-350 range).