While this article is mostly concerning underwater photography, many of the basics remain the same for general photography. This article uses Adobe Lightroom as its photo editing tool and most commercial photo editing tools have similar interfaces and functions.
Underwater photography is probably amongst the hardest types of photography that the not professional photographer can encounter. Not only does a photographer need to have the skills necessary to come back alive, they would also need to have sufficient skill to properly frame and expose the photograph.
Of course you will need a camera capable of being taken into the water but you will find an additional light source to be almost essential for good photography.
The waters around Victoria have an abundance of marine life, lots of plant life near the surface and lots of marine critters from the surface to deep. The cool waters and active currents provide a well oxygenated water (for the animal life) and the sunlight drives the basis for most of the marine life here, algae.
Salt water absorbs most colours of light, the deeper you go you will find the colours that you might see change. The first to go is red followed by yellow and eventually green fades away until all you get is a blue green tinted grey and black. The suspended algae in the water also helps with the light filtering process, the water acting as a green filter that gets progressively more green the further you are away from your subject. I have been on a number of dives where the surface is sunny and bright yet it looks and feels like night down below.
Unless you are content with shades of grey or are not willing to go more than a meter or two in depth, you will find a supplemental light to be an absolute. Of course, as the light from your light passes through the water, you will find the colour changes. First as the light travels through the water to your photo subject, and secondly as the light reflects off your subject and travels to your camera. And this colour constantly changes depending upon distance and even by the amount of biological activity.
i use an electronic flash as my light source for my still photos and a daylight balanced video light for my videos. It is possible to do still photography with a video light provided you have a high enough level of illumination. The $50 eBay video lights simply do not provide enough light for still photos, yet I have used them for video with action cameras.
My setup
I use a DSLR in an underwater housing and use one or two electronic flashes to light the scene. I use TTL lighting (automatic exposure control) and set the camera for manual exposure. The flash provides enough light to light the scene and the manual exposure is set to darken the background and to eliminate camera shake. F 11, 1/125, ISO 100, and single point auto focus. The light levels in Victoria waters are rarely bright enough to have over exposure. I try to keep my photo technique as simple as possible, it is too easy to get task overwhelmed when diving and that is when mistakes happen.
I don’t tend to shoot underwater landscapes, usually the water is not clear enough. So, i concentrate on the marine life.
Most electronic flash have a colour temperature of 5500 degrees Kelvin, that is close to daylight in colour balance. Above water, you would set your cameras white balance to daylight or flash to get a good colour balance.
In the water, from experience, I set the cameras white balance to 4500 degrees Kelvin. This, in part, offsets some of the effect of the water filtering out some of the colour of light. I do not adjust the magenta/green colour balance in camera. That is too variable.
I go ahead and take the photo, find subject, frame, focus, and expose. I try to frame as tight as possible, I try to get my lights as far as possible off to the side(s) of my subject. This is to not illuminate any suspended particles in the water. And I try to stay away from my fellow divers. One inadvertent fin kick and the scene will be filled with a sandstorm of gunk.
At the computer
I load my images onto my computer, open the files in Lightroom and do a quick survey of the photos. I quickly delete the duds.
Before getting into the serious photo editing, I make sure that my computer screen is properly setup. That is, calibrated to industry standards for brightness and colour balance. Most Apple laptops come properly calibrated from the factory, other types of computers should be calibrated using a tool like a Datacolor Spyder.
Next I will open the first photo in the develop mode and set the white balance to, As Shot, I make sure that Lens Corrections is turned on, and I increase the amount of texture. I then go into the Grid mode (G), select all the photos and Sync my settings. This ensures that all the photos start from a similar start point.
Deselect all the photos ( you really do want to do this) and then select the first photo to edit.
Take a quick look around the photo and see if there is something that you think should be white or a neutral shade of grey. Use the White Balancing Selector (W) and click on the object that you think should be white or neutral grey. You just might have properly colour balanced your photo. If not, try some other object. I like to use broken pieces of shell. The insides of freshly shed crab shells are usually white, older pieces of shell usually have a thin layer of yellow/green growth.
The colour not quite right? Using the Temp and Tint sliders will allow for adjustment of the colour. Move one and then the other until you get the colour balance that makes your photo glow. Sometimes turning up the saturation to 100 will show which colour is too strong. Just turn down the saturation afterwards.
Having your colour balance off too far makes some colours look too dominant and makes other colours look dull or just off looking. And often your photo will look just dark.
As in all photography, the important part of the subject is where you work first.
Adjusting your exposure might help you get a better colour balance. Then work on the contrast, highlights, etc. Once you have set the best setting for exposure, move the sliders but don’t be afraid to hold Shift And Double Click on the word Highlights, etc. This allows Lightroom to give you its suggestion for this particular setting. I find that the Auto setting often does not get me close enough to my wishes.
Once I have the exposure and colour balance looking good I will adjust the Clarity and /or Dehaze to help emphasize my subject. I will also use the masking tool to select the background. i then will often darken the background, reduce sharpness (to get rid of suspended particles) and also dial down highlights and whites to further reduce the look of suspended objects. And last I crop, to get rid of any other unwanted objects.
The video file shows the effect of changing distances and its affect on the relative quality of light. Close up has better colour of light, further away shows more of what the ambient light looks like.
And one last point. You have several choices to make concerning underwater colour balance. Do you want what your eyes would see without additional illumination? Or, would you rather have a more full colour experience? And lastly, if you are looking for scientific authenticity of colours, you still have a ways to go to get there.