Type of beam? Spot+Spill or pure spot?

Hello divers,

I would like to know your preferences about beams patterns, so that is the purpose of this thread.

When we are out of the water -surface- we usually need a spot+corona beam type. Of course the proportion of those ones can vary depending on the type of light we are using: We can have a "thrower" with a narrow beam and dim corona, or something more balanced, which is usually more confortable when you want to use that light to walk by. In this case a spot too defined or too bright will be against any task on close distances... but again a wide and brigh corona will be against our capability if we want to searc for something far away. (Searchlight)

But into the water the rules change. Even in the clearest water there are a lot of particles in suspension, causing an important backscatter and reflection, and that makes a "light tube effect". This effect in fact is illuminating all the area arround the axis of the beam, reducing the need of spill coming out from the front of the light.

But, even if we can reduce the need of spill, my opinion is that we can not always trust on the conditions of the water to create that peripheral lighting. Peripheral illumination help to orientate us and to warn about dangers and risks coming from the side (The real ones)... and I'm not necessarily talking about sharks or the kraken, but wires, nets, cutting edges...

What do you think? Some of you are already making your own lights with "pencil type" beams? What are your experiences?

Yesterday I took some photos on smoke to see the difference (You can see them in my subforum)... and you will see that there is little difference on regular corona+spot, pure spot and dim corona+bright spot.

Javier

Personally I prefer a very tight spot for daytime use, so I can shine the light under ledges and rocks without having to actually poke the light in close into the ledge.
For night diving my preference for a primary light is about a 20 degree spot, with a 45 degree spill. This allows for some range, but also gives some peripheral vision (the spill gives the ability to check SPG without blinding yourself).
Where I dive in NZ, the visibility hovers around 10 meters, so exceptional throw is not really a requirement.

I like a nice tight beam. 8 degrees or tighter. No spill.
This works well for low viz and helps eliminate back scatter. Its also great for signalling to your buddy.

I dont do much night diving, due to a serious lack of shore dive sites in Auckland and I dont yet have a radar on my boat but a wider beam would be preferable.

With a low lumen light i would go for a tight beam. Then you can light up your target.

If you got plenty of lumen spill is just a plus. As long as the light wil carry the distance you are looking for. Only disadvantige i can see is problems signaling and blinding your friend divers. With my new 3600lumen light this can be a problem(but i'm not the one beeing blinded so there is really not a problem :laughing.

Fluor said:

With a low lumen light i would go for a tight beam. Then you can light up your target.

If you got plenty of lumen spill is just a plus. As long as the light wil carry the distance you are looking for. Only disadvantige i can see is problems signaling and blinding your friend divers. With my new 3600lumen light this can be a problem(but i'm not the one beeing blinded so there is really not a problem :laughing.

Click to expand...

What light do you have? 3600 lumens sounds nice to me :thumbsup:

300winmag said:

What light do you have? 3600 lumens sounds nice to me :thumbsup:

Click to expand...

By the sound of it should be DIY or a Metalsub HID200.

Greetz Johan

I think it's his quad P7

heffay said:

I think it's his quad P7

Click to expand...

My friend, that is music to my ears! :twothumbs

Personally i like about 10 deg. Then you get the best of both.

Yes, Gav, but... 10º and no corona??

I have been doing some tests on murky water. You can see them under Barbolight subforum.

I'll keep on with that testing this week, comparing to a reference 10º 50 Watt Mr16 Halogen.

My conclusions are:

Pure spot lights are unconfortable unless you have enough ambience light. They make a tunnel vision, and difficult orientation.

Here you can see a picture comparing a U-04 Dive, 27 mm reflector, vs a U-04 proto aspheric. Both use same driver, same LED, fresh from the charger battery.




As you can see even on quite murky waters the reflected light coming from the main beam is not enough to make a usefull peripheral vision. Anyway, we are working on it.

Regards,

Javier

Sorry but I see very little difference in the pics.

I would agree about pure spot in dark environments like caves or night diving.
But for open water dives including deep dives I prefer as spot. Even in wrecks where the light from a spot is reflected around giving a flood or flight but minimal back scatter.

My prototype had its first dive last Sunday on the wreck of HMS Sidon. It was 35m, viz was about 5m so was average for UK, and it was dark as night down there. I've used a 35mm reflector on an MC-E. I'm very very pleased with its performance. It gave a strong, narrow hotspot with a nice spill too. The hotspot area was useful for penetrating into the wreck and seeing into the nooks and crannies, but the spill was also useful for lighting up that little peripheral area which stops you from feeling a bit claustrophobic when its both dark and very murky. My buddy was using the light and was really happy with it. I made it for him to replace his 50w MR16 halogen light.
So, for me it would be a choice of a strong hotspot plus a corona..