Telephoto - a new technique for underwater

The key to successful underwater photography is getting rid of the water! This cliched expression is as old as underwater photography itself, but it remains a key tenet of the technique. If we shoot through too much water it saps the colours from our images and reduces the clarity and contrast. As a result we spend our dives getting as close as we can to our subjects and choose lenses that focus very close: wide lenses to photograph scenery and macro lenses to snap the little stuff. In my opinion this leads to a rather restricted view of the underwater world. Physics becomes the bane of creativity.

This is a problem because creating new images is one of the main goals for a photographer Ð and from the first discussions about the photography for The Art Of Diving one of the most important goals was to create a set of images that really stood out as something new. Photographers can look for new images in lots of places. Personally, I have found that my new digital equipment has been a particularly productive pasture. I believe that we should not just be using our new digital cameras to try and recreate the images we took on film. No. We should understand how these cameras differ from traditional methods and then exploit these differences to take entirely new types of images.

My digital telephoto story started in the summer of 2001. A friend of mine had just bought his first digital compact camera and taken it to the Red Sea. His camera, without external strobe or lenses, had cost a fraction of the price of a Nikonos V, yet his pictures from this first trip were superb. He came back beaming, Alex, I thought you said underwater photography was difficult! Soon several of my diving friends were returning from their first trips as photographers with equally impressive results. I did not want to immediately doubt the skill levels of my friends, but surely not all of my buddies were going to become the next David Doubilet. It got me thinking. Why were these simple digital cameras so good?

First, the LCD screens on the back of their cameras would show them, after each exposure, what each image looked like. If they made a mistake they could correct it. But this was not the whole story. The most common mistake of all underwater photography newbies is to not get close enough to the subject; their early pictures lack colour (they are too blue) and also clarity and contrast. Why didnt my friends pictures show this mistake? The reason lies in the brains (OK, programming and processor) of their digital cameras. When their digital cameras saw their overly blue, low contrast images, they recognised something was wrong and dealt with it Ð adjusting the colour balance and boosting the contrast accordingly. Their digital cameras were allowing them to bend one of the key rules of underwater photography.

So how can we more experienced photographers exploit this feature creatively without significantly degrading our image quality? The rest of this article is about my experiments combining telephoto lenses with the power of RAW files.

A telephoto is a lens that incorporates a telescope, thus providing greater magnification than we can see with our eyes. Put another way a telephoto is a lens with a focal length greater than a standard lens of 50mm (on a full frame 135 format, 35mm, camera). Throughout this article, for the sake of simplicity, I will convert all focal lengths into their equivalent on a 135 format camera because there are lots of different digital sensor sizes out there on DSLRs. For most of my telephoto shooting I have been using a 160mm lens and generally use a camera to subject distance of 1Ð 2 metres, although the two Hogfish were taken with a 230mm lens!

RAW files are often likened to the digital equivalent of negative film. The camera has recorded the scene Ð but in the printing process you can still adjust colour balance, exposure, saturation, contrast etc. The big advantage of the RAW file is that these adjustments are made before the final image file is created and therefore do not degrade the quality of the image anywhere near as much as making such strong adjustments on a JPG file in Photoshop. If we shoot JPG, the camera can make these same adjustments when it reads the data off the sensor and creates the JPG. The problem is that these choices are then made by the camera and locked in. The RAW file gives us the opportunity to control these settings and make these choices when we are back on dry land.

My main motivation for experimenting with telephoto photography was to exploit the different photographic perspective it offers. Wide-angle lenses produce images with a steepened perspective, pulling the subject forward away from the background and giving a shot an almost three-dimensional effect. This is great. And it is one of the reasons why we like them so much underwater. But if you have ever judged through a reel of wide-angle slides you will soon realise that the effect is used repetitively in underwater photography. A long focal length lens used on large subjects is different, and while it is unsuitable for many underwater situations, if it is used selectively and appropriately it can create a stunning images that add a spark of originality to a portfolio.

Well, that is the theory. It is rather more difficult in practice. The first problem with a lens designed to bring distant objects into closer view is shooting distant objects means shooting through lots of water and our images loose the three Cs: colour, contrast and clarity. Lighting the picture with flash is part of the solution, but also creates the additional problem of backscatter, which is always accentuated by increased camera to subject distance. For telephoto photography I use paired strobes, pushed out wide from the camera to reduce the amount of water that the lens is looking through AND that the strobes are also illuminating. I am also able to push the lenses forward, well in front of the camera because the long focal length lens means that its field of view is narrow enough not too see them. Finally I have the strobe heads angled in slightly so that the centre of the beams crosses about 1.5 metres in front of the camera.

The other important factor in avoiding backscatter and getting clear images is visibility. Telephoto is not a low Viz technique! I have found that the old rule of fin that visibility must be at least 5 times your camera to subject to distance is a good guide (2 metres camera to subject needs 10m Viz). The long camera to subject distances also require quite wide apertures to ensure that enough strobe light is recorded on the subject. I usually use something in the F5.6-F8 range.

Even with this setup the images are not perfect straight from the camera. Unsurprisingly, they have the typical look of images that have been shot through too much water Ð albeit without the backscatter problems Ð and all require adjustment in the RAW converter software before the JPG, TIFF or PSD file is produced. I am big fan of AdobeÕs Camera Raw plug-in, which comes as part of Photoshop CS, although there are other Raw converters available. My main processing steps on a telephoto image are warming up the white balance of the image (colour temperature and tint) and increasing its contrast. A digital compact will tend to apply stronger processing in camera and will require less tweaking by the photographer. But by the same token it offers less control.

This may seem like a lot of effort to go to correct a deliberate mistake. The obvious question is what is the payback? It is in several areas. First of all the longer working distance is excellent for filling the frame with large but shy subjects. Species that have always had the tendency to turn away when you approach them are now easy prey. I must admit it can feel like cheating! I am sure we have all experienced dives where we have had a camera problem and the fish just seem to know and spend the entire posing in front of our faces. Well this time the tables are turned - it is as if the fish dont even think I am a photographer!

The technique is also well suited to natural history photography, allowing us to get frame-filling images without disturbing the behaviour of the subject. When I have dived with videographers I have always been jealous of the behavioural sequences that they have captured. One of the reasons they are able to get such great shots (in addition to their skill, of course) is that they often film the action from more than 1 metre from the subject. A telephoto provides the digital photographer the same opportunity.

The next advantage is the reduced depth of field associated with using a long focal length lens. I am sure you have admired the wildlife images of land photographers. These are invariably taken with long lenses and show a crisply focussed subject popping out from a smooth, out of focus background. Now we can recreate these shots underwater. Furthermore, the narrow angle of coverage of a telephoto is also very helpful for isolating a subject against a background that does not distract the eye.

My favourite feature of the telephoto lens is that it flattens perspective. A telephoto pulls the background of the image closer to the main subject. This can let us draw attention to background details that would be too small and insignificant in a wide-angle photograph. A good example is the portrait of the grumpy Bohar Snapper. The telephoto has pulled the other snappers forward into this image so that they become part of the story. But at the same time the narrow depth of field keeps the background in soft focus and attention on the main subject.

The most obvious criticism of this technique is that image quality must surely be poor because we are shooting through too much water and then applying large post processing corrections. Such a question highlights one of the big difference between digital and film. On slide film the answer is definitely yes. On digital, specifically with the flexibility of RAW files, it is not the case. RAW allows this processing to be completed without significant deterioration of the image quality.

The problems with telephoto lie elsewhere. First a telephoto is not suitable for all subjects and the look of the images quickly becomes quite repetitive. I see telephoto a niche technique Ð not one that we can use on dive after dive. The other problem with telephoto is rather embarrassing to explain. My main fear when shooting telephoto is that other underwater photographers are laughing at me. Who is that idiot photographing fish from a couple of metres away? DoesnÕt he know the basic rules of underwater photography? This really came home to me when taking telephoto shots on the USAT Liberty Wreck in Bali, where there were plenty of other photographers in the water. I kept seeing them swim past and I wanted to explain what I was doing! I couldnt.

In every other way I have found telephoto an exciting new technique. I am taking pictures that look like nothing I have taken before and capturing subjects that have always proved elusive. Telephoto encourages us to try something different, to back away, and get a new perspective on underwater subjects.

This article was first written for Underwater Photography Magazine, issue 20 and was published in August 2004. The version above is actually a revised version, that was re-written in 2006 for The Art Of Diving website.