Primary light for cave diving

[MarkHerm]

At the moment I am in the business of buying my first can light as I want to progress to cave diving maybe within the next 2 years.
I totally understand that communication is vital in caves and that your light source is your primary communication device. Hence I see that cave divers look for a focused beam. While researching different options and brands I often come across folks praising a light for its tight beam with almost no spill. Please forgive my ignorance but is a very focused beam with basically no spill really the thing you are looking for in a primary light for cave diving? Isn't a good amount of spill/corona necessary to illuminate the cave? After all I assume that you not only want to communicate in the cave but also look around a little?!
Still I rarely see this aspect discussed when choosing and comparing primary lights. Is it a none-issue?

Just to give you an concrete example, I was researching the Light-for-Me 4TEC LED primary light which is quite popular around here in Europe. It is praised as being almost as bright as a 21w HID but being half the cost. I came across this youtube video where it is compared to a 21w HID in the pool by night. The beam tightness and brightness seems to be relatively equal but if you look at the light spill, the 21w HID seems to be the winner. Just have a look at the last twenty seconds of the video (starting at 2:12; especially the last two seconds of the video) and compare the spill on the ground of the pool of the two lights. The 21w HID clearly illuminates the pool floor but the LED seems to only have very little spill. Still I have never heard anyone complaining about the LED having too litlle spill...


So how are active cave divers see this? Do you go for the tightest beam possible? Do you care for the light spill of your primary light? If you can adjust the focus on your primary light, will you always go for the tightest setting possible when cave diving?

I really appreciate your input as a can light is a heavy investment and I don't want to get the wrong tool for my goal (=cave diving)...

[saxplayer1004]

the problem in that video is that the hid is a hair brighter than the led so it's drowning it out. both lights are about equal from what i can tell in focus points and corona but the hid is a bit brighter. I'd take that LED over the HID for price and durability factors alone. It's difficult in a cave to have different strength lights because they wash each other out. Having the tight beam is much more important in tannic waters and great lakes type diving here where there is limited visibility. In the caves the tight beams are useful in brownouts, but during a brownout the people I dive with will go to black out diving configuration. get on the line and touch contact. Just makes it easier, especially because most of us close our eyes during brownouts anyway to avoid vertigo.

[PfcAJ]

"Brightness" is a tough thing to quantify without things like lux and lumens.

From my experience, LED anything doesn't penetrate murky water (tannins, silt, sulfide, etc) the same way an HID does (at least not yet). Narrow beam is what you want for signaling, esp through murky water. A wide beam just doesn't cut it.

I'd go with a proper 21w HID with a 9ish amp hour battery. Enough power to cut through the muck, with enough spill to see the cave. That will carry you a very long way in cave diving. The 21w bulbs are quite robust, and a 9ah battery will give you about 4 hours of total burn time. Used ones pop up pretty frequently and reasonable prices, but make sure the seller knows the burntime of the battery.

[BabyDuck]

i'm sure the guys are right, and don't have anything to add about 'what you want'.

just a small point, because i see what you mean about potentially wanting to 'light up the cave to see more'. you will look wherever the light is. it's sort of like having one of those camping headlamps on - even a smaller light is adequate (provided it matches your buddy's), because you'll be looking at whatever you're pointing your light at. it's not like walking around outside in daylight, it's like walking around outside at night with a flashlight - there's no need to light up the next quarter mile, just your next couple of steps. so unless you're doing pictures or video, a tight spot is fine.

[TSandM]

I asked a similar question years ago, and the answers were right, once I got there to see. First off, white limestone reflects light, so the amount of light in the cave is more than the focused beam you bring. Second, most cave diving is done in teams, so you have more than one light operating at a time. Third, you "paint" the cave, and your brain puts the lighted parts together into a picture that is brighter than what you actually saw. (I'm always amazed, on my first dive of a trip, at how much darker the cave is than I remember.)

You need an adequately focused beam to communicate well, but some spill is not a problem, once your buddies are used to it. If I were going to buy a light today, I'd probably go with an LED, for reliability and durability, even though they aren't quite as bright.

[Doppler]

Allow me to add a totally different two cents-worth.

At a guess, I have 'invested' in more than 15 cave lights over the years... My first a monster built by Lamar English, the last something altogether different from the guys at Light Monkey.

I no longer use a canister light. I feel they are old technology and above all boast so many failure points they are a joke. My current cave light is a sealed system handheld LED.

Look at what's out there and investigate alternatives to the traditional canister light... I think we are at a tipping point of sorts.


Just saying

[ajduplessis]

This is something I posted a while ago when someone asked about LED vs HID. These are my views.



You are going to get various responses based on what diver’s use, what instructors recommend and what people believe is the way forward. I am no different and use a Halcyon 12w LED, thus my opinion below. I love my light and have dived it in a team of 21w HID’s and other LED’s.

You want a very reliable high performance light/bulb, long burn times, deep depth rating, short recharge cycles and should have a focused beam of around 8 degrees.

I would like to use my Halcyon 12W LED as “soundboard” to highlight pros and cons between HID and LED dive light. You can make up your own mind on what is good, bad or BS.

Firstly the matter of reliability. HID bulbs do break when bumped or dropped by accident unlike LED’s and in my opinion then less reliable. HID bulbs are also costly to replace.
Secondly a dive light should have long burn times. HID lights eat battery power and you require increasingly larger packs to increase burn times. I have a 4.5amp hour pack and will burn for 5 hours at 100% (double that on 50%). A typical HID would only last around 2 hours on the same pack. My 4.5ah pack only requires a 45 min to charge which is great. Please also remember that it is a small pack and thus less buoyant compared to 9 or 13ah packs.
Thirdly a dive light should have a tightly focused beam. The light I have is not as focused as a typical HID (10degrees only) and some would say not any good for signalling/tracking. I disagree, if you can’t see me signalling you are blind or 3000 feet away. As mentioned I have dive this light in a team of other 21w HID and performed great!!
Lastly we need to look at performance. 21w HID lights are more powerful with regards to punch, but not by much. Please remember that I am comparing a 12w LED to a 21w HID. The LED IMO has a whiter and brighter beam.

I have dived this light with cavers using 21w HID and they are comfortable to have the 12w LED within their team and was “impressed” by its performance.

I believe that LED is already to a standard and in some cases starting to surpass HID in performance.

[Dive Bug Bit Me]

I dive with the HID technology and it works just fine for me. I have had buddies with both LED and HID in caves and wrecks. It might be just me, but the world does feel like it's moving towards LED's as the dominant light.

I find the HID is a little brighter. This has benefits when looking around, but drowning out your buddy's light makes keeping an eye on him a pain. It can be done but you need to be more focused on this.

I have quite a lot of scatter from my HID. This does mean I have needed to adjust my signaling. My arm movements need to be more vigorous than most as I need to Swing the full light beam (plus scatter) over the diver to get attention. The plus side is I find it easier to see more of the cave (a personal thing).

Technology is getting better all the time. This means LED's produce ever improved beams, but it also the HID's burn times are improving and the they are becoming more robust. My HID has a tough life and would have about 20000 air miles, 100 boat launches, numerous falls and bumps and so far only one bulb.

I guess that ultimately it comes down to personal choice. Either are good and will do the job.

[mathauck0814]

I dive with a 21w LED and find the light to be whiter than my friends' equivalently powered HID. The LED lacks the "punch" of the HID, however we travel a lot and I can check my bag while he carries his on (to baby the fragile and expensive bulb) so I think the trade off is worth it.

[MarkHerm]

Thanks guys!
I get from your feedback that spill light doesn't seem to be a major consideration when selecting a primary. Most of the better primaries let you see what you want to see in a cave...
With respect to HID vs LED I am pretty much settled on LED because of reliability considerations. Additionally LED tends to be less expensive and I don't think I need the ultimate "punch" that HID may provide for my first can light. LED technology is improving fast at the moment so personally I will not get a top of the line light now as I suspect a major change in the not too distant future.

Allow me to add a totally different two cents-worth.
I no longer use a canister light. I feel they are old technology and above all boast so many failure points they are a joke. My current cave light is a sealed system handheld LED.

That is an interesting comment. I already did some research on non-canister primary lights but always got the impression that we are not quite there at the moment (either they lack power or lack burn time or both). What do you use?