P7 or MC-E for Max Throw?

[nwbrewer]

I posted this in the LED forum and it was recommended to try here for more interest -

I'm working on building a new divelight, and right now I am considering 2 options.
I'm going to be using a AA Ni-mh battery pack to run my divelight, but they'll go in the can. My orignial plan was to use a D-bin p7 and tightly focus the mag reflector to give me a nice narrow beam. This is what I do now with a P4. I ordered some 1.4amp AMC drivers from DX, and was going to run 2 in parallel. (4AA's supplying each driver for extended runtime)

Now I'm considering switching to using an M-bin MC-E and Optics, since it sounds like optics will give me a more narrow beam that I'm looking for. I'd still use AA's , but make a 3S2P style pack (I wouldn't charge it this way) and one of the 1.4 amp AMC drivers to run the MC-E configured for 2S2P.

Thoughts? Which is going to give me the best output? Tightest beam for diving throw?

Thanks CPF!

Jake

 

[Mettee]

this may helps

http://www.candlepowerforums.com/vb/showthread.php?t=203029

 

[2xTrinity]

For a divelight, I think you may want to consider going with a warm white emitter, even at the cost of some lumens, as I believe this will give you better contrast. As far as I know, the only place to get warm or neutral white is with the MC-E, from cutter.co.au, which are about the equivalent of $18-20 USD shipped.

Underwater, especially as you dive deep, longer wavelength portions of the specturm (eg red and orange) are absorbed more by the water. This means the ambient light is largely devoid of red. If you use a cool white LED, which has most of its energy in the shorter wavelength end of the spectrum, it will transmit fairly efficiently through the water, but it will still look fundamentally the same as the blue-shifted ambient light.

If you use a neutral white like a 5A (4200K) or warm light like the 6A bin MC-E (3500k), you will be doing something analogous to white balancing -- your artifical light source will be disproportionately strong in the long wavelength portion of the spectrum, offsetting the red-deficiency of the ambient light. You will notice dramatically improved color contrast as a result.

Oftentimes people on this board have commented that they have found that incans with fewer than half as many lumens as comparable LED lights seem to "work better" outdoors, and it's a similar concept -- it's because lumen-for-lumen the warmer-tinted light is better at producing useful color contrast.

I woudln't go warmer than 6A though (lower than 3600k), as the warmest LEDs start to get a lot less efficient inherently, and you will lose more light to water absorption, as well.

 

[Packhorse]

I disagree. I find a cool white is much preferable for underwater use. The warmer colours get soaked up too quickly.
Most HID dive lights are 6500K

Its not really about finding something neutral unless you are using it for video/photo work.

 

[Barbarin]

I disagree. I find a cool white is much preferable for underwater use. The warmer colours get soaked up too quickly.
Most HID dive lights are 6500K

Its not really about finding something neutral unless you are using it for video/photo work.

+1. Agree completely.

For photo o video warmer colors are better, but for that you don't need a thrower. For throwing is more important cold colors.

Javier