Taking pics underwater
I often get asked why I have used certain settings and how I get such strong colours in my photos. The answer isn’t a simple one as underwater photography is very different from normal land based photography.Unlike air, water absorbs light with red being the first to go followed by orange, yellow, green than blue. So to get the true colour of items underwater an external light source must be used (except if you are in very shallow water where the absorption hasn’t happened yet). The problem here is water is full of particles, sand, krill, algae etc and the light source illuminates all these particles and creates backscatter , making it look like it is snowing in your picture. The only way to get rid of this is to eliminate the water between the subject and your lens, in other words you need to get close. Any further than a meter or two, no telephoto lenses here, and you are either going to get a lot of backscatter or you will have a blue tinted picture (due to light absorption). Getting very close to wild animals requires a lot of patience and stealth like ability with noisy scuba gear on, you need to slow down your breathing and reduce your movement. Even when this close strobe placement is vital to reduce backscatter .
Notice the backscatter in the water
Most serious underwater photographers have two strobes attached to their camera and the positioning of these is vital for getting good results. The light source (strobes/flashes) needs to be as far away from the lens as possible to reduce backscatter while still lighting your subject. The strobes need to be set to have the outer edge of the strobes light just hitting the subject and not lighting any water in front of it. Then there is the issue of light intensity and if you want any shadows so the picture looks natural. The aim is to have some shadows form but still be am to see details in them, having your strobes set at different intensities does this, oh and by the way TTL strobe use is not very effective underwater (it can work sometimes, but manual light settings is the best way to go), and then the shadows should match the naturally occurring one in the picture or having the brightest strobe giving light from the direction of the sun, if that is in your picture.
Good strobe placement Bad strobe placement
Fish also tend to locate themselves where they can camouflage in their surrounding, silver fish hang around sand and coloured fish sit next to the reef, so taking a picture of them in their surroundings can make it hard to see the animal and/or the picture looks two dimensional with no depth as shown in fig 4 (The turtle is hard to see here). So the aim is to usually get blue water behind the animal and angle upward (to see the surface or sunrays) to get the fish out of its environment and give the picture some depth, as shown below.
Fig.1 Fig. 2 Fig. 3 Fig. 4
Due to the tendency for the animals underwater to meter so much differently than their surroundings I tend to use spot or center weighted metering, meter the surrounding environment set my camera and then use my manually controlled strobes to light the animal, I only ever manually set my aperture and shutter speed for exposure, with you and the animal constantly moving, control of the shutter speed in the darkened underwater environment is essential, I also find the camera never gets it right underwater. Underwater shutter speed tends to control the background exposure and aperture controls whatever the strobe is lighting. Most of the time I use an ISO of 400 on my Nikon D200 so I can keep the shutter speed up a bit, but never go any high than that to keep the quality in the water which pixilates very easily. I have never used continuous shooting underwater because the strobes can’t charge themselves fast enough to keep up with the shutter so it single shot shooting with a slight pause between shots, you also only get one go at a lots of shots because once the flash goes off the fish usually either swims away or changes what it is doing, so time is very important, it’s very easy to be a premature shooter because you think you might miss the shot, but you only end up with a very blue tinted picture that you can barely see what is going on if you do. You need to be confident in your ability to get the shot and hold back pushing that button until you are close enough for your strobes to light the subject. As for lenses I only have two that I use underwater, a Tokina 10-17mm fisheye for all my wide angle stuff and a Nikon 60mm for all my macro stuff. I love the Tokina for its ability to focus so closely, important when I need to get rid of the water between the subject and lens, the only problem is if I get a stray bit of hair or dust in my underwater housing the lens can focus on that, annoying when you are 20m underwater. The lens also lets me take self portraits with a number of animals that I encounter, this takes a bit of practice to get the angles right.
My camera housing with two external strobes – fits either a Nikon D200 or D300