Very specific question re. which light

[Kharon]

I am having the most extreme trouble getting anyone to answer this question which is very simple and extremely specific. Everyone seems to want to include a camera, video advice, filter advice. I don't want any of that. I only want the answer to eaxctly the question that follows.

At 60 feet in gin clear water and at distances of 3, 6, and 9 feet from a Spotfin Hogfish (bright red and bright yellow), with which light would I see (with my eyes - no camera) the colors of the fish better at the center of the beam - a 1500 lumen 110° beam light or a 700 lumen 75° beam light.

 

[lucca brassi]

I don't know how good you see ? ;-)

 

[diveprof]

DRIS Dive Gear 1000 Lumen Dive Light | Dive Right In Scuba - Plainfield, IL best ratio of $ to quality and durability in a non-can dive light.

 

[Linedog]

I dive with my Hog Morph video light as my primary light. I like the way it doesn't washout colors to my eye. My Hog is 2000 LM, so I would go with the 1500.

 

[MRTdiver]

... with which light would I see (with my eyes - no camera) the colors of the fish better at the center of the beam - a 1500 lumen 110° beam light or a 700 lumen 75° beam light.

My calculations are coming up wrong. But apart from that here's something to think about.

And that's finding out the CRI.

CRI stands for color rendering index. And measures the ability of a light source to represent colors as they appear in natural light. 100 being a perfect representation - such as natural sunlight, a candle, incandescents.

Cree XM-Ls are popular emitters. If both lights are using XM-L emitters then they range from 65-90 CRI.

color temperatures (K): CW = cool white; NW = neutral white; WW = warm white

Usually CW emitters have the lowest CRI, while WW have the highest...


From XM-L2 Data Sheet (this is the 2nd generation of XM-L). See pg. 3 of PDF.

> Typical CRI for Cool White (5000 K – 8300 K CCT) is 65.
> Typical CRI for Neutral White (3700 K – 5000 K CCT) is 75.
> Typical CRI for Warm White (2600 K – 3700 K CCT) is 80.


So when video light manufactures list their color temp. that may give you some indication of the actual CRI.


I've changed LEDs on flashlights just to do what your asking about.

 

[lucca brassi]

This fish can reach a length of 28.5 cm (11.2 in), though most do not exceed 18 cm (7.1 in).

Not to be such ass I have calculated ... (0,91m/1,82m/2,74m) (in Europe we wearing different shoes ;-)) )

1500lm /110°/ gives /676,07 lux/169,02 lux/74,58 lux

700lm /75°/ gives /651,04 lux/162,76 lux /71,82 lux

By this calculation illuminated surface is uniformly light without hot spots !

So....... light illumination is almost same , just little ,little better is 1500lm /110°

Now give me cookies ;-))) .....for reward !

 

[Kharon]

Thanks to all. Very helpful.

The DRIS only has an 11.5° beam. Much too narrow for what I want though the price is exceptional.

lucca, you get cookies every time you visit the forum - the problem is that it's your computer that eats them

 

[PeterNBiddle]

Thanks to all. Very helpful. The DRIS only has an 11.5° beam. Much too narrow for what I want though the price is exceptional. lucca, you get cookies every time you visit the forum - the problem is that it's your computer that eats them

I made a diffuser for the DRIS out of an old piece of a plastic (milk?) jug I found on the beach on Utila. It worked well to reduce the focal intensity of the DRIS without dimming it too much.

 

[Lorenzoid]

. . .
At 60 feet in gin clear water and at distances of 3, 6, and 9 feet from a Spotfin Hogfish (bright red and bright yellow), with which light would I see (with my eyes - no camera) the colors of the fish better at the center of the beam - a 1500 lumen 110° beam light or a 700 lumen 75° beam light.

Others have given some technical answers, but from an intuitive point of view, how we perceive colors depends mostly on the color of the light and not so much on the brightness or beam width (assuming you're somewhere between the 3 and 9 feet you mention). To determine the answer to the question, we would need to know how "white" (or not white) the light in question is. Some lights are referred to as "warm" while others are "cool." Lumen ratings and beam width have little to nothing to do with it. Someone correct me if I'm wrong.

 

[SlvrDragon50]

Lmens and beam angle definitiely play a factor. If the beam doesn't even reach the fish then it wont make a difference what temperature the bulb is. That said, bulb temp will affect colors.