Image © David Peake

by Alexander Mustard

Reproduced from in focus 73 (Feb. 2002)

During the last year, I have been trying out a technique called zoom blur and have had the chance to show a couple of the resulting images at BSoUP meetings. Zoom blurring is achieved by zooming a lens while the camera’s shutter is open. This records an abstract image with zoom lines radiating from the centre of the photograph, produced as the zooming alters the size of the subject in the frame. In this article I hope to pass on some of my experiences with this technique.

An acroporid coral and anthias in The Alternatives, Sinai, Egypt

An acroporid coral and anthias in The Alternatives, Sinai, Egypt. Nikon F100, 17-35 mm Nikkor (zoomed through full range), 50 CC Red filter (depth = 5.0 m). On f22, aperture priority – exposure time approx. 1/2 to 1 sec. Kodak Ektachrome Extra Colour 100.

I would like to say that it was a result of inspired forethought and detailed planning. But in truth, it was two events on a BSoUP Red Sea trip, which were quite beyond my control, that led me to try the technique of zoom blurring underwater. The first was a lunchtime chat with Colin Doeg, the BSoUP Chairman, who was offering the opinion that underwater photographers could produce some really original images if they tried out more of the photographic techniques used by land photographers. At the time, I did not agree, arguing that because of the technical difficulties of producing clear, sharp and colourful images underwater, we cannot easily import techniques used on land. The second event was far less pleasant! On my penultimate night on board my flash guns packed up. And after an unproductive session with a multimeter and the extensive use of expletives of similar colour to the ocean, I made the executive decision that my final day of shooting should be a ‘natural light’ day!

The next morning I stuck a 50 CC red gel filter to the rear element of my 17-35 mm zoom, detached my flashes and arms and set off on a 4 m dive. At four metres a 50CC red filter will provide approximate colour correction in blue water, so there was no need to go deeper. Or shallower, a colour correction filter must be the best way to keep an underwater photographer from diving sawtooth profiles! The amount of colour correction needed is estimated as 12 CC units of red filter per metre of light path from the surface, to the subject and on to the camera.

The fastest film I had with me was 100 ASA, which even at 4 m only gave me exposures of 1/60th at f2.8 through the filter. So after a few shots fighting the lack of depth of field, I decided to work with the lack of light and try some long exposures, sticking my camera on aperture priority and stopping down to f22. One of the advantages of using filters for long exposures is that the colour spectrum of the image is consistent and correct throughout the exposure. When we use flash in long exposures (such as rear curtain) the flash light has a different colour balance to the rest of the exposure, which may or may not be pleasing.

At f22 I got exposure times of between a half and one second. Such long exposures gave me time to think, my thoughts returned to Colin’s comments from earlier in the week, in particular the technique of zoom blur. So, in order to relieve my boredom while the shutter was open, I decided to try zooming the lens. I was operating on guess work, and I didn’t really know what sort of mess I was making on the film!

Fire coral and anthias in The Alternatives, Sinai, EgyptFire coral and anthias in The Alternatives, Sinai, Egypt. Nikon F100, 17-35 mm Nikkor (zoomed through full range), 50 CC Red filter (depth = 4.1 m). On f22, aperture priorityexposure time approx. 1/4 to 1/2 sec. Kodak Elitechrome Extra Colour 100.

In general, I got my best results by zooming from wide to short focal lengths, and I prefer the images where I left the lens at the wide end for a few moment before zooming, which produced a well defined background onto which to overlay the zoom blur. The characteristic trails produced by zooming are clearest when dark and light subject matter are juxtaposed, such as light corals and dark blue water. Large blocks of solid colour, such as open water, do not produce trails but make an effective background for trails or improve composition by providing negative space within the image. I would recommend wide-angle zooms for this technique underwater, and if possible a lens with a constant aperture throughout the zoom range.

In order to get accurate colours I ‘bracketed’ the correction by taking pictures at several depths within a metre or so of 4 m. With the benefit of hindsight, I don’t think that this was necessary, because accurate colour correction is not essential for such abstract images. It is also worth noting that with an SLR you certainly cannot believe your eyes when looking through a colour correction filter! At 4 m the filter worked well on the film, but in the water my vision had adapted to the in situ colour spectrum and the view through the camera looked far too red. The bottom line with colour correction is to trust your depth gauge and not your eyes.

One consequence of long exposures is keeping the camera stationary during exposures. A tripod is good solution although it is not a typical accessory for underwater photography in the Red Sea. Certain dive sites lend themselves to long exposures: wrecks for example provide a number of places where we can brace a camera. In the Red Sea, I produced acceptable results by hand holding the camera.

After my experience with zoom blur in last summer, I fully recommend that it is always worth taking a break from the tried and tested techniques that we have profited from in the past. Also, I now agree with Colin that adapting a technique from another branch of photography can produce original and unusual images underwater! And next time I may even try out some of these techniques when all my kit is fully functional.

An additional thought!

But before rushing out to give zoom blurring a try I feel I should also let you know that this effect can easily be imitated using the wonders of Photoshop! Zoom blur can be added to any image by using the zoom function of radial blur (Filter: Blur: Radial blur). It is worth noting that the computer has several advantages over the camera as well as meaning you don’t have to get wet. First you can select any photograph, including colourful flash lit images, from macro to fisheye. Also the extent of zoom blur is precisely user defined, and the origin of the blur can be set anywhere within the image. When the technique is produced in camera the origin is always in the centre of the image.

Coral trout on reef, Sha'ab Abu Nuhas, Egypt

Coral trout on reef, Sha’ab Abu Nuhas, Egypt. Nikonos V, 15 mm UW-Nikkor. Sea and Sea YS120 flash gun. On f8 aperture priority(1/60th) TTL. Zoom effect added in Photoshop to right hand image Filter: Blur: Radial Blur.

This image of similar subject matter to the in camera shots shows the before and after effect of a single application of radial zoom blur in Photoshop.