Flash vs LED

Packhorse

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Well my dive light/s are working well, but now with a new camera and housing on the way Im thinking of either buying a strobe (flash) or perhaps building a LED camera light. Has anyone tried this and what sort of success did they have? I would assume it would require many LEDS of a daylight tone a wide angle reflector with a very even beam. Can anyone recommend a reflector? I saw a video light that seemed to work well, it had 9 leds laid out in a triangle. Each LED had its own reflector about 10mm in diameter. The light head was just over 52mm. In fact it was just big enough to screw on a 52mm camera style filter. Actually it had 2 of these set ups. Perhaps something like this would work well.
 

Al Combs

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Found a link. They were the Sunray 1000 1000lumen. Also there is the 2000 lumen 18 LED model.

Wow, 2,600 bucks for the cheap one.:faint: I guess that explains why you're thinking of building one. Just kidding. BTW, your dive lights in the avatar was a great post. Being a builder, I'll bet you can do a better job than them.

Do you really need any kind of reflector? What you want for photography is uniform illumination across a wide field of view. If you look at the product gallery from your Sunray 1000 link, the frontal view of the reflector they use is more of a shield to prevent stray light. I doubt if it's reflecting any significant light from the steep angle light leaving the Cree emitter would hit even the edge of it. IMO, they put a reflector there to look pretty. What you really want is a big ZebraLight.

I have a case. The size of a 35 mm film (which nobody uses anymore) is 24x36 mm or 43.267 mm on the diagonal. Using a 50 mm lens, that diagonal measurement translates into a 46.79° field of view. If you look at page 8 of Cree's Data Sheet in XLamp7090XR-E.pdf, there is a graph called Typical Spatial Distribution. Guestimating from that graph, there is still 85% illumination at the corners of the film at 23.4° off axis, with no reflector.

The SSC P7 is even better in this case. On page 9 of SSC's W724C0.pdf, there is an equivalent graph called Typical Dome Type Radiation pattern. The same Lambertian dome that causes donuts in my MagLite gives better than 80% illumination out to a 90° field of view. You could use a 21 mm lens (35mm equiv) with 80% illumination in the corner of the frame using a P7.
 

Sabrewolf

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Underwater photography is a tricky little devil to master.
If you are "Just" doing pictures, and not video... A Flash
is your best bet to better sneak up on fish with.
A high power led light will only scare away the little
fishies. You would also cut down on gear quite a bit
if you purchased a flash instead due to less batteries
and weight. And i am sure you have enough on your
hands to deal with when it comes to taking "Just"
pictures. As far as a diffuser goes, Try an Opaque
lens cover for a scatter effect. But keep your flash
as far away from the lense as you can with a 45 degree
angle to it. My dad does underwater HD video for
PBS with a Sony Semi-pro setup. He has to sneak up
on the fishies and then turn on the leds "Just" to be
able to catch them in action if for only a few seconds.
That is where you have the advantage of a One-Time
light to illuminate your surroundings.

If you do decide to go with an led set, i can build a nice
rechargable one for you with the Warmest colors
possible. I would usually add some red leds into the mix
to offset the blue hues of the ocean. The red wavelength
does not go down to far to make things appear natural.
You may get about 20ft or so before the reds and
yellows go all muddy blue and green :mecry:.

I work with lucite/lexan on a regular basis. So its not
a problem to build you a housing with some nice
High-CRI leds in there. The Nichia brand is a quick
one i can think of.. Let me know if you are interested,
and we can talk about a proper setup for ya :candle:

:poof:
Robert M.
 

Packhorse

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THanks for the offer Sabrewolf but I really enjoy building my own gear. Check out a couple of my previous dive light projects here.

I know what you are saying about a flash vs a light in regards to sneaking up on away fish and its a very valid point. My thought on this was to use a optical trigger to sense when the cameras built in flash activate and then have the LEDs light up then or have the abilty to turn them on and leave them on for getting shots of other subjects.

The extra gear and weight of the lights will not really be a problem. I doubt I will be using my can light at the same time so thats one less piece of equipment I will be taking along. The G10 canon and housing I am looking at is very buoyant so requires a weight to keep it neutral. I simply intend to use the battey casing as the weight that screws to the base of the housing.

Al Combs, you may well be right in regards to not using a reflector. I will definately research this some more. Thanks for the links.


I think my main concern is will I be able to actuly get enought light out of the LEDs to match a strobe?
 

Al Combs

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I was so busy babbling about lenses and field of view I completely forgot about the fact that cool or even warm white LED's have very little red output in them. The idea of putting a red LED for every 4 or 5 white ones of the same power level makes a lot of sense.
 

Sabrewolf

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I was so busy babbling about lenses and field of view I completely forgot about the fact that cool or even warm white LED's have very little red output in them. The idea of putting a red LED for every 4 or 5 white ones of the same power level makes a lot of sense.


I don't blame ya for overlooking that one :grin2:
It is a Hole Nuther' Wurld Down in them
thar sees... (pirate speak)
But at least you still remebered it :poke::candle:
Some of the people that do photography/video
in the water tend to forgo the red overtones that
get washed out. Our "Eyes" see better than any
camera could ever reproduce on a tiny viewscreen
to even "Fathom" (hehe) where the Reds have
all gone :thinking: (where didtheygoboss??) And they
just do alot of post production work to try and
revive those muddled colors.. And in the process,
Make more work for themselves in the long run..
Ohh weeeellll.
You could also try some "Infra-Red" leds as a
brightness suppliment when taking pics under
coral/rock ledges. It is another not-so-known
trick that keeps the fishies right where you
want them, instead of :poof:ing!

:candle::popcorn:
Robert M.
 

nwbrewer

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Jan 14, 2008
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THanks for the offer Sabrewolf but I really enjoy building my own gear. Check out a couple of my previous dive light projects here.

I know what you are saying about a flash vs a light in regards to sneaking up on away fish and its a very valid point. My thought on this was to use a optical trigger to sense when the cameras built in flash activate and then have the LEDs light up then or have the abilty to turn them on and leave them on for getting shots of other subjects.

The extra gear and weight of the lights will not really be a problem. I doubt I will be using my can light at the same time so thats one less piece of equipment I will be taking along. The G10 canon and housing I am looking at is very buoyant so requires a weight to keep it neutral. I simply intend to use the battey casing as the weight that screws to the base of the housing.

Al Combs, you may well be right in regards to not using a reflector. I will definately research this some more. Thanks for the links.


I think my main concern is will I be able to actuly get enought light out of the LEDs to match a strobe?

If you figure out how to make an optical trigger work, please post it, I'd love to give it a try. I've held the Sunray 2000, it's really designed more for video work than as a strobe. I'm pretty sure it's running nichia LED's, they're much smaller than an XR-E or a P4. I'm thinking about making a maglite one with a single 18650 and 4 XR-E's in parallel. Use a really wide distribution optic on all 4. The only thing I've been trying to figure out is how to make the synch work with the flash.
 

H20doctor

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I would just stuff one XRE in a mag housing.. And put one on both sides... That would provide a lot of light depending on the optics, you could have a nice flood, or a tight spot ..
 

Packhorse

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The Sunray 1000 used XR-Es as far as I could make out. I assumed the 2000 does too.
I dont see any point in an optical trigger. You would not get the benefit of pre shot illumination.
Forget about the optics. Just use them with no optics. Gives a even wide angle beam.
1 XR-E per side will just not provide anywhere enough light.
8 K2's provide nearly enough for close up shots.
 

nwbrewer

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From actually holding the thing in my hand (the 2000) I'd swear the emitters were WAY smaller than an XR-E. I was thinking I could use it like a strobe. I'd still need a small focus light, but I could also get away with a single 18650, or probably a smaller Li-ion battery in the light and get quite a few pictures out of it.
 
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