Understanding Underwater Photoghraphy

<p>The research I've done so far suggests that a problem with taking photos under the ocean's surface is that sea water absorbs red light and that other than a strobe there are two solutions, one, to use a filter that converts some light to red and, two, to adjust the white balance (or otherwise adjust color levels). But if the water is absorbing the light, then it is doing so to the light that reaches the human eye as well as to the light that reaches a sensor. So my first question is this: Is the goal in adding red in underwater photos to alter the photos and make the images look better than they do to the naked eye (and there would be nothing wrong with that), or is the eye more sensitive to red light than film or a digital sensor and so by adding red, the image better approximates what the eye sees?<br /><br />This leads me to my second question. Panasonic point-and-shoot digital cameras have a natural light scene setting for "snorkeling and beach." This confuses me. A digital Snorkeling setting, I take it, adjusts the white balance to emphasize red that the water removes (just a small adjustment, as compared to what would be required at depth). Ok, but why in the world would the same adjustment be used for a beach scene? A beach may be bright and may have an unusual mix of colors, much different from neutral gray, that, like snow, could fool the camera's auto-exposure suggestion, but what does that have to do with water's absorption of light, which is what, I take it, an underwater setting is all about? Thanks in advance.</p>

<p>Probably not the specific answer you are looking for but, . . .</p>

<p>The ultra-violet rays of sunlight is what you lose the deeper in depth that you go. As I remember it becomes more obvious below about 20 feet.</p>

<p>My underwater experience was all done in the days of film, so I don't really have any experience with the digital settings modern cameras may have to improve on the loss of UV rays underwater.<br>

I can see where possibly some White Balance adjustments may be helpful but, think it would only provide minimal advantage.<br>

None of the underwater photographer's I knew back in the late 70's ever mentioned using filters but, then again we were all using multiple Strobes.<br>

Most "natural light" shots were taken above 30 feet and always had that blue-green tint.</p>

<p>Actually, I think you have it backwards. Red light gets absorbed first, then orange, yellow, blue, etc.--ultraviolet would be the last to go. My question, regarding the light loss was whether the brain compensates for the loss, allowing the eye, but not film or a sensor, of course, to see red when there is even just a little of it. (And then I had the second question about digital camera settings, but that's separate.) Anyway, a strobe fixes the problem, providing full spectrum light right at the depth of the camera, but I was asking about non-strobe issues.</p>

<p>It is not only the spectral charecteristics but also the quantity of light underwater. Your brain will compensate a little but the underwater world, starting with 2-3 feet or so, looks dim and blue to humans no matter what.</p>

<p>In the digital world the "proper" underwater WB setting allows some colors to be "truer" to reality but still with a rather strong blue cast, red, or any other, filtration or not. The only remedy is to deliver a lot of full spectrum light, which is not an easy task underwater. As for some filtration guidance, you may want to read up on using daylight-balanced slide film underwater and on the spectral characteristics of KODAK Ektachrome UW (yep, UW stands for underwater.) Of course, this is all history but very relevant to your question.</p>

<p>As an aside, P&S cameras offer some settings for beginners/rank amateurs who pay rather little attention to image fidelity, hence the dual "beach/snorkeling" setting.</p>

<p>Thanks, I'll look at the Ektachrome UW. As for fidelity, I notice that if I take a blue tinted scene complete with, say, a blue tinted sea turtle, then adjust the R, G, and B levels separately, I can turn the turtle brown, which I know to be its true color (or at least truer than blue). My question is really whether this adjustment, or a physical filter that will accomplish the same result, is restoring reality in some way or just painting the colors until the image looks like my guess at what reality must be. My sense is that the answer is a mix of the two, that the reason the level adjustment works is that there is enough red light in the captured image that making the turtle brown, instead of blue, is possible, but that in the end the adjustment using levels or a physical filter is just a guess at reality. As I say, I'll read further, though.</p>

<p>And as for the P&S dual "beach/snorkeling" setting, I'm willing to concede that the camera manufacturer is doing nothing more than fabricating the consumer's sense of a proper image, but I remain mystified that the same setting accomplishes the desired fabrication in both environments. That is, my question is not "why" but "how."</p>

<p>The trouble with digital is that it is nothing like film, hence optical filtration while shooting doesn't change the fundamental spectral characteristic of the "sensor" as it does with color film (which is most sensitive to a certain "prevailing" color temperature) but instead introduces a rather uniform color cast across all color channels (I'm oversimplifying here so don't shoot.) I suppose a CC40 Cyan filter might help (with some messing around with the blue channel in post) but a custom UW balance setting (obtained in the actual shooting environment if your housing allows it) would probably work better IF (and only if) you have enough sunlight or full-spectrum artificial light available. Sadly, the most cheerful, colorful underwater pictures are made in shallow water with white sand bottom, and close to the surface :-) Once you get deeper, everything becomes murky and colorless unless you have a power station with you AND shoot very close.</p>

<p>As for the "beach/snorkeling" WB setting: both are a classic "lots of blue" scenario (a blue hue underwater and blue shadows, lighted by the light reflected from the blue sky, on the beach) so the WB setting - surprisingly - might be very close for both.</p>

<p>It might be worth trying an 81C, which corrects for too much blue (with film).<br>

No filter changes the spectral characteristics of film. Filters modify the spectrum reaching the film.</p>

<p>Thanks for the advice. For stills, actually, the solution is pretty simple I've learned through experimenting over the past few days: separate adjustments for the Blue, Green, then Red channels will eliminate the blue tint (in a way that a global white balance adjustment does not for reasons I don't quite understand). A filter might still help for video, though (Then again, for video, I'll mostly be shooting my kids at the surface watching the fish and, thus, am not all that concerned). My question, was, I guess whether the human eye sees the blue tint too--I don't quite recall from my last snorkeling trip--but I think the answer must be yes, as others have said. But the human eye (brain) must tend to know what's white and adjust other colors accordingly. Thanks again.</p>

 

<p>The human eye also perceives colours according to any significant amounts of adjacent colours or the colour it has just viewed for more than the briefest of times.</p>

Lobalobo, Galen Rowell I think said it correctly and profoundly. Color is not real. We bring strobes underwater to add color and even

then different strobes have different color temperature. The color of a reef at 60 feet to our naked eyes is blue green as that is what

remains that can be reflected to our naked eyes. But who wants to look at a blue green sea scape, so we alter the color underwater

with strobes that have an effective range of only a few feet to satisfy our esthetic sensibility that is day light and land based and

therefore has greater visible spectral frame of reference. That we perceive as more "natural" looking. As you said there is

nothing wrong with that. Additionally our brains have evolved to like warm colors so in our film days many shot with an 81a warming

filter on their lens. Now days We do similar in photoshop. Good hunting.

<p>Well put, Edward. I suppose what is typically meant by "real" color is the color that would be reflected to the eye if an object in a vacuum were lit by a source of neutral temperature. But, as you say, there is no non-arbitrary reason to consider that color "real." </p>

<p>The underwater mode in most digital P&S cameras doesn't do as much white balancing as removing the apparent extra blue in most photos not taken with strobes.<br>

Bill</p>

<p>A good place to start your underwater photography experience is in the safer and manageable confines of a swimming pool. You can learn how to handle the camera in a wet environment; and if it falls to the bottom of the pool, then you don’t have far to go to retrieve it. Use your friends or family members as practice subjects. Shoot images from various angles above the water, at the water line, and then underwater.<br>

Get more tips from the following articles :<br>

<a href="http://www.nikonusa.com/Learn-And-Explore/Nikon-School/fu02mcno/1/Underwater-Photography.html">http://www.nikonusa.com/Learn-And-Explore/Nikon-School/fu02mcno/1/Underwater-Photography.html</a><br>

<a href="http://www.photographytalk.com/photography-articles/677-photography-tiphow-to-introduce-yourself-to-underwater-photography">http://www.photographytalk.com/photography-articles/677-photography-tiphow-to-introduce-yourself-to-underwater-photography</a></p>