Some questions about Underwater video lights.

[Minos2014]

Hi . All divers

This is Minos, Recently I was study about underwater video lights.I am a new for photography ,So I have some questions I want to consult to export here.

The questions related to below dive video lights

http://image4.pushauction.com/0/0/a...a795/9c480c5c-5d4a-d51d-5c0d-47bbe8adc881.jpg

Image tags removed from Hotlinked image - Norm

Feature
◆ Bulb: White CREE XM-L2 U2 LED *8 (max 5200 Lumens);
Red CREE XP-E N3 LED*4 wavelength 620 nm (max 400 Lumens);
Purple LED *2 wavelength 410nm (max 6W);
UV LED*2 wavelength 365nm (max 6W);
◆ Switch 1: Red> Purple> UV> off
Switch 2: White high> White medium >White low> off
The two switches can be operated separately or simultaneously.

Questions
1.From my experience,Only warm color temperature(3500k-4000k) will be more suitable for photography,But this camera didnt advise the color temperature. So. Does the color temperature matters to be a good video light?

2.Red CREE XP-E N3 LED*4 wavelength 620 nm (max 400 Lumens);
What's the utility of red light ?I have no idea in what situations the red light can helps.

3.Purple LED *2 wavelength 410nm (max 6W)
What's the utility of Purple light ?

4.UV LED*2 wavelength 365nm (max 6W)
What's the utility of UV light ?


I am sorry for many questions, I am not a diver,But I have to work out this problems.in case of my clients ask. I will very appreciate for your help and you know I like this place. This is a good place for ask a question.

Thanks
Minos

 

[Packhorse]

1. Im not so sure a "warm" colour temp as is important as a LED with a high CRI . The more natural the light being used the better the video. So if you want a really good video light use hi CRI LED's.

2. My understanding is that fish are not disturbed by the red light and so the red makes a good focusing light for strobe photography.

3.Not sure what the benefit of purple is.

4. UV light can bring out phosphorescence in many underwater subjects. It can make for some interesting photos.

 

[Minos2014]

1. Im not so sure a "warm" colour temp as is important as a LED with a high CRI . The more natural the light being used the better the video. So if you want a really good video light use hi CRI LED's.

2. My understanding is that fish are not disturbed by the red light and so the red makes a good focusing light for strobe photography.

3.Not sure what the benefit of purple is.

4. UV light can bring out phosphorescence in many underwater subjects. It can make for some interesting photos.

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Very appreciate for your sharing. I think UV light is Purple light.

 

[lucca brassi]

For biophosphorescence is ''as I have undertand '' researchers / photographers better '' royal blue'' between 450-460 nm

 

[DIWdiver]

Violet is a shade of purple, and is the highest energy wavelength visible to the human eye. Ultraviolet is a higher energy wavelength, and in its pure form is not visible to the human eye.

UV lights often look purple/violet because they emit a range of wavelengths, including violet. However this is not normally true of LEDs.

The light you show claims to have both purple (violet) and UV LEDs. They are definitely different. You would be able to see the light from the purple ones, not from the UV ones.

As I recall from my college physics days (MANY years ago), higher energy wavelengths should make things fluoresce better. I suspect that royal blue (which is lower energy than violet) is popular because the LEDs are cheaper and more efficient, and the energy is high enough to excite many marine organisms' fluorescent compounds.

 

[Barbarin]

The light seems to be OK, but I would use 32 XPE2 well distributed rather than 8 XML's. Those LEDs are with no reason too close, and the shadows they will generate will be too "hard" and defined.

Other than that it is becoming trend to use red LEDs to enhance this wavelength while using CW LEDs. Nowadays I think it has no sense as long as with most LEDs we are getting same efficiency on NW than on CW, and the CRI is much higher. Anyway, everything can be corrected (and in fact is corrected) during the edition. The key here is the lack of flicker, which would affect seriously the recording.

There is a reason though to include the UV LEDs, as they can get colors which are not there... which is somewhat "cheating", as editing.

Regards,

Javier