Dumb questions about complete reef lighting

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pauldw

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I'm not an underwater photographer, just a rec diver, but I've long wondered about something. The typical photo of a reef shows gorgeous color right by the diver, since that's all lit up with strobes, and then everything further away is washed out because sunlight gets stripped out of most of its colors as it penetrates the water. Theoretically, if someone put a massive array of lights underwater, maybe something like a batch of Batman-like searchlights, or just many panels of LEDs, would it be possible to get a picture of an entire swatch of reef in color, or would the light catch everything floating in the water and just be a mess (apart from heat, scaring animals, and whatnot also being a problem)?
 
Water filters color in all directions, not just sunlight from above. Even if a light is right on top of the subject, color is still filtered before arriving at the camera lens regardless of how bright. The greater the distance, the more color is lost. And if the light source is with the photographer, then the light has traveled 2x the distance to the subject. Take a photo of an object 10ft away using strobe or video light, and the light has traveled (filtered) through 20ft of water.
 
It's kind of possible with a combination of cooling filters on lights/strobes and a warming filter on the lens. You won't get as much color in the foreground, but the color definition that you do get will penetrate a lot deeper into the shot. @Interceptor121 did several articles on the subject.
 
You could do it with surface supplied lighting, maybe. Not a chance with a strobe (Assume a GN of 40 which is bigger than any common strobe) which UW means like maybe 15. Remember GN=Fstop x distance. At f 5.6 this means you can light up something about 10 feet away. Pretty small reef.
Bill
 
If you can illuminate up to 10 ft away with good colour which is probably a stretch realistically, then if you illuminate the reef 20feet away it sees the same colour as you would get from strobes 10' away as it has the same round trip.

So realistically you can only double the distance with good illumination with off camera lighting. To make a nice photo you have to work out how to include the blue-green coloured background reef (ambient light lit) into your composition - the simple approach is to mostly fill the frame with well lit reef by getting close and paying attention to the way you frame the scene and from which angle. Another trick is to under expose the ambient light a little -if that part of the scene is darker it appears to recede in the photo.
 
Chris: Doesn't the GN of the strobe take into account the round trip. I am confused (but that is common) about your comment. I like the idea of underexposing the background unless you are trying to make it blue.
Bill
 
Well yes it sort of does, but the point is that in this example if at 10 ft away you start to shift from full colour to noticable blue green The light has travelled out 10' and back 10' for a total of 20' . Use that same output on a strobe 20' away and you'll get the same lighting on the reef 20' away as you do 10' away with the on-camera strobe, because the light does not need to travel out and back, it's a one way ticket. - this assumes the distance light travels from off camera strobe to reef is negligible, it probably is not so it is actually less distance that you can gain.

So the point is the strobe light travels through the same amount of water in each case and has the same amount of reds/yellows sucked out. You can place a light further out but it travels through more water still and is no better than the first bit of reef to start to look blue-green 10' away.

The take away is that an off camera strobe can only approximately double the distance that is well lit by your on-camera strobe if both emit the same amount/colour of light. 10' is just an example it might be less or it might be more. that the colour in the strobe lighting starts to fade away.
 
Sure, that is what I suspected you meant. My point was supposed to be kind of a joke, thinking about the kind of lights that the early Cousteau guys used with a generator on the boat and big cables running down. In any case for me it is mostly moot, I shoot wide angle only once a year and am caught up til 2021.

Cheers and happy holidays

Bill
 
I cannot remember where I stored the photo but there three divers using open sensor optical fired strobes with me in a dive. My strobes were closed sensor optical cable fired. Whenever any of those fellas where even close to me, when I would fire my strobes their strobes would also fire, much to their dismay. I was in the middle of the group on drift along a wall and I noticed everybody was aiming there cameras at the same basic area. I quickly aimed and snapped the shutter and used my two strobes and there total of six strobes to light my scene. It actually sort of worked. Soon they caught on to my trick, lol :wink:.

Photobucket destroyed so much, here is one showing a similar affect but just a single diver and strobe. But, yes, you can position optically controlled strobes, on purpose, to light greater areas. Still, as mentioned, the water quickly absorbs the light and differentially, the color (reds first).

IMG-4161-zps65888754.jpg



N
 
Getting the BIG Picture - DIVER magazine

It's not only theoretically possible, it's been done at Bloody Bay wall in Little Cayman. He had to use mosaics and stitch images together, but each image was still huge.

Bloody Bay Wall Project (unfortunately, still Flash)

And the original was done with film! Incredibly ambitious project. There are some shots of the strobe setup in this doc - it's pretty amazing:

 

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