New diver beam angle questions

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tdallen

Contributor
Messages
131
Reaction score
37
Location
Somewhere south of Boston
# of dives
50 - 99
Hi, I'm a new recreational diver with a couple of questions related to beam angle. I'm looking to buy my first light or two. They'll be used for dark areas on daylight dives and possibly some night dives, in New England as well as some warmer/clearer parts of the world. No video or photography, just want to see what's down there.
  • In New England water I know backscatter becomes an issue. But what beam angles work well in silty water? I'm sure 60*+ becomes a mess, but what about 30-40*? 15-20*? Is it necessary or advisable to go all the way down to 8*?
  • Do the focusable lights like the ones from Bigblue and Tovatec work well?
  • Do you consider beam angle when picking primary vs. backup? I.e, a wider light for primary and a narrower one for secondary?
  • Should I even worry about this, or just buy a decent looking light? :D
I've got no real experience and it seems like there are tons of choices, so any advice appreciated!
 
For any given light, the tighter the beam, the more light you have directly where you are pointing the light. I've got two lights, one with a 40* beam and one with an 8*. I find that the 40* just doesn't have enough light for my tastes. The 8* beam covers pretty much the area I am looking at during any given moment, so I much prefer it.

Of course you can spend a lot of money on high powered lights that can give you a nice bright, wide circle, but for my money, I've been pretty happy with some of the tight focused lights. FWIW, I use the handheld LEDs from Dive Gear Express.
 
I like a fairly tight spot, like 15, but with plenty of spill out to 60 too. You would not want a perfectly focused projector, the spill is important. Never used a focusable underwater, but suspect it would be more trouble than it's worth; they always have weird artifacts anyway. With the advances in batteries and LEDs the least few years, my 'primary and secondary' are identical cheap chinese things that get the job done. Don't stress too much on it unless you are doing serious video or technical stuff. Spend that cash on more tank fills!
 
tighter beams have more punch, particularly for signaling in silty water. In open water, I prefer a wide beam. I don't think I'd use an 8° beam except for cave diving or wreck penetration.
 
After reading John and Kelemvor's posts I should probably follow up with a caveat. I've spent most of my adult life working in forests at night, where it is really dark! As such, I'm quite comfortable being in very dark places. Whether topside or underwater, I've found that I like having a nice bright spot to illuminate the area where I'm looking. Underwater, I find the the spill from my 8* beam adequate to illuminate the area that I want to look at. Some folks may simply prefer a wider angle.
 
In New England water I know backscatter becomes an issue. But what beam angles work well in silty water? I'm sure 60*+ becomes a mess, but what about 30-40*? 15-20*? Is it necessary or advisable to go all the way down to 8*?

The really wide beams, such as those in the range of 40-60 degrees, are usually marketed for video. I agree they might make "a mess" in silty water.

The 6 and 8-degree lights are marketed mainly for cave and wreck divers. The tight beam satisfies cave and wreck divers' need to communicate with each other by light signals. We recreational divers don't typically rely on light signaling to the same extent they do. Traditionally, a cave or wreck diver would use a handheld light as a backup light and use a larger, more powerful, and possibly focusable (so as to allow both signaling and looking around) light as their primary. Such tech-oriented lights with long burn times tend to be very expensive. If a tech diver has switched to their backup light, it's because their primary light failed, and the diver is making an exit from the cave or wreck, so a wider beam is not useful. That said, there are apparently people like RyanT who like such tight beams as primary recreational lights. I would guess that most recreational divers find such a beam too narrow for their tastes.

I don't dive in silty conditions, so I can't comment directly. If you are truly doing most of your diving in nasty conditions, then maybe consider the same kind of powerful primary light used by cave and wreck divers. Keep in mind that in clear, tropical conditions, those lights will scare off critters as you approach. For tropical night dives, I use a surprisingly low-power light.

For recreational dives, there is no inherent reason why your primary and backup lights cannot be identical. Mine are. The terms "primary" and "backup" don't really have much meaning--whichever light is in my hand is the primary, and the one that is stowed in case the primary fails is the backup. But they are identical lights.

For recreational diving, I could see using a focusable light if you want to shoot video as well as look around, but that's about it. Getting a focusable light (which I assume is relatively expensive) just because you sometimes dive in silty conditions for which a narrow beam might be ideal seems like overkill.
 
For recreational dives, there is no inherent reason why your primary and backup lights cannot be identical. Mine are.

Indeed, with LED technology there are quite a few small, but bright lights available that are easily stowable when not in use.
 
Thank for all the feedback.

I like the idea of a larger visible area than 8*, either with a wider beam or a light that throws a halo around a hotspot. I like to vacation in warm, clear water but here in New Englance I know (but don't have much experience with) that the water visibility can cloudy as the summer goes on. The few videos I've been able to find of water conditions like that only show the hot spot cutting through...
 
In very clear water, you may be happy with a wide angle and very powerful light. However, diving New England, in most situations the visibility is going to limited, often with a good degree of plankton and particulates in the water.

In these types of situations, the particulates act quite similar to a fog. As in driving your car, you blast into it with bright lights and all the particles are illuminated, the fog "glows" and you end up with a bright haze in front of you with poor visibility at distance. This is very similar to diving, in turbid water.

You want to penetrate the water and light up things "past" the water, not make the water in front of you glow. A tight angle light will be much more effective under these conditions, even though a relatively limited portion of the underwater scene will be illuminated by your light. There is no doubt that you will see farther with a tight focused light

We offer a wide angle, video light - 890 lumens, a great video light, but not so good for turbid water and general diving.

Our 680 lumen light has a very compact and focused beam and you will be much happier with this light when the visibility is 6 to 20 feet.

680 Lumen Dive Light | MAKO Spearguns

M680DL-2T.jpg




We recently added another light to our collection. This is an amazingly small and quite powerful and very focuses LED light which has a very secure clip for mounting on your mask. This is a great light for scuba divers at night or very dark conditions, to allow them to see their gauges and more or less anything which is in front of them. So small you can wear two of them and if you buy a pair we discount them.. $20 a light, $32 for a pair. FYI, the lanyard is not used when worn on the mask strap. It can also be carried as an extremely small back up light for emergencies, will fit into any BC pocket. This light is about as big as a man's pinkie finger and a little bit longer - takes one AAA cell.


Both lights are high quality, anodized aluminum.

Mini Dive Light | MAKO Spearguns

MMDL-2T.jpg
 
https://www.shearwater.com/products/perdix-ai/

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