Tint vs brightness

[MrNaz]

Would using Cree P4 LEDs which are available in 7A and 7B bins be a good idea for a dive light? How would this compare to the use of R2 LEDs in a WH bin?

The P4 is significantly less bright than the R2, but the tint would be far warmer, which would be a big asset while diving underwater.

What do other divers think?

 

[DM51]

It will not make a lot of difference, as the warmer reds and yellows are soon lost underwater anyway. Even a powerful incan can do nothing to mitigate the effect of the red part of the spectrum being completely lost after 5 meters (15 ft) through water.

I dive with an incan light for close-range observation and photographic purposes, but for run-time, reliability and distance work you need an HID or LED, and its tint is largely irrelevant.

 

[MrNaz]

It will not make a lot of difference, as the warmer reds and yellows are soon lost underwater anyway. Even a powerful incan can do nothing to mitigate the effect of the red part of the spectrum being completely lost after 5 meters (15 ft) through water.

I dive with an incan light for close-range observation and photographic purposes, but for run-time, reliability and distance work you need an HID or LED, and its tint is largely irrelevant.

I mainly use my light for close up examination of objects. Long range spotting is not something I usually do, as my dives are usually just to observe nature.

That being said, there is no reason I can't build more than one light, one with 4x R2 LEDs for ranged spotting with narrow beams (probably best for wreck diving), and one with 4x P4 LEDs in warm bins for those dives where I want to see the colours of clown fish and moray eels.

For close up examination would warm bin LEDs be beneficial, or should I just stick to incan when I wand to see colour?

 

[2xTrinity]

I've looked a bit into tint vs brightnes for underwater LEDs (I was involved in a project where I installed LED lights on an autonomous robotic submarine in a situation where color vision at short range was important.

I found the neutral white LEDs in the 5x range were really the "sweet spot". I wouldn't go warmer than 6x (I actually got several of those in MC-E from cutter a while back and they worked ok). Neutral was a big advantage over cool for perceiving warm color. Goign warmer didn't produce that much better perceived color, but did lead to a lot lower output for two reasons: 1) lower inital output from the LED, and 2) absorption of long wavelength in water.

The combo light with narrow-angle cool for throw, and wider angle warm for close is probably the best idea. If you were don't a "one size fits all", I'd go for a multi-chip light like an MC-E in a neutral white. And I'd use an optic rather than a reflector (direct "spill" out the front I've found is bad in murky situations. A wider-angle optic will do better for close range in my experience than letting the light "spill" out of a reflector.

 

[Packhorse]

I think its very dependant on the water. If you dive in blue water then a blue tint will travel further. Green water and a green tint will. I dont think warm of neutral tints are of that much benefit ( unless filming).
The reason why is that due to lack of colour your eyes/brain adjusts to suit. And of course when you use a cool tint it still shows up colours and these will still appear very bright and vivid in relation to non illuminated objects underwater.

 

[DM51]

I mainly use my light for close up examination of objects. Long range spotting is not something I usually do, as my dives are usually just to observe nature.

For close range observation purposes I would highly recommend an incan light. Even the warm LEDs will be relatively poor at showing up the red end of the spectrum - they are not very good at this out of the water, so when underwater with what is effectively an additional blue filter, the effect will even be more pronounced. I'm not saying that with a LED light you won't see any red at all, but red objects just won't be as bright as when they are properly illuminated. They'll look relatively dull. For most other purposes LEDs are better underwater, but until high-power high-CRI LEDs are made (like a turbo-charged version of the LED in a Sundrop) incan still has its place.