Modern zoom lenses and digital cameras can focus subjects very close to the lens and this has brought macro photography into the hands of many. The Nikonos RS 50mm macro lens was a technical feat for its time, being able to auto-focus down to 16.7cm (6 diopter range). Such lenses are formidable work-horses as they give such a wide range of enlargement.

One could also define macro photography as where mixed light photography ends and maximum strobe light begins.

Beginning underwater photographers often enter the arena with severely limited camera equipment and this is still very much the case today, even with digital cameras in underwater housings. The salesman never tells them what the camera won't do and what its limitations are under water.

One of the problems found with cameras with separate viewfinders or sportfinders is that of parallax. An obstacle could protrude in the line of sight without the photographer noticing, but this is but the least serious of problems.

Surely the biggest problems plaguing the underwater photographer is that the strobe light is difficult to control. It so happens that the intensity of the light diminishes quadratically with distance, which creates high uncertainty. So by taking photos at a fixed distance, with a fixed intensity of light is one of the ways to increase success. This makes fixed-distance macro photography an easy start for beginners, yielding colourful pictures that can be entered into competitions.

The arrival of the Nikonos IV and V who were able not only to meter ambient light, but also to control the strobe, was a major leap forward even though the more thoughtful photographer used self-controlled thyristor strobes before that. It was now possible to attain even lighting with variable distances, and this greatly enhanced the chance of success. However, these cameras were still not able to focus automatically such that most evenly lit photographs were usually out of focus.

Understandably, non-amphibic reflex cameras with automatic focusing, TTL (Through The Lens) light metering and strobe control, housed in separate underwater housings became popular. Their only disadvantages were often clumsily placed controls, an excessively large housing (to accommodate several brands), and optics not correcting for the water interface. But very good photos could be taken with them.

The Nikonos RS (Reflex System) came out in the beginning 1990s but was taken off the market in 1996, even though it remains today the most sophisticated underwater camera system ever made, delivering also the sharpest images with the most comfortable controls. It is truly a formidable work-horse.

It is clear that macro photography is done in many ways, using the various camera systems, but underlying it all is the theory of lenses, depth of field and the limitations imposed on lighting systems. With this general knowledge, we hope you will be able to improve your chances of success.

The drawing shown here captures the basic law of optics defining where an image is focused. On the right the subject with distance s to the lens. On the left the focal plane with distance o to the lens which is made up of a shift of and focal length f of the lens. The drawn dashed paths of light are special cases: all light parallel with the optical axis pass through the lens and focus in its focal spot f inside the camera. This also works in reverse and light exiting the lens in parallel with the optical axis will have come from a symmetrical spot f outside the lens. all light rays going through the middle of the lens are not refracted (bent) and pass straight through. In this manner one can construct in a graphical way the basic law of optics: 1 / f = 1 / o + 1 / s  (discovered by Descartes)

The physicist Newton formulated the basic optics law noticing that the distance from focal plane to focus (of) is inversely related to the distance from subject to the equivalent focus outside:  of x sf = f x f
With Newton's formula one can quickly calculate how far to move the focal plane to focus on a distant object.
 
 

From simple trigonometry, one can see that the magnification is given by: m = o / s
So the further the lens from the focal plane (o becomes larger as s becomes smaller), the more magnification is achieved. Obviously for a 1:1 magnification, o = s  and this happens precisely when d = f . A 35mm distance ring should thus achieve 1:1 magnification for a 35mm lens.

One may ask how many diopters a 35mm lens is. The diopter is defined as one for a lens with focal distance of 1 meter. In general, the diopter strength = 1 / f  (in metres). Thus for a 35mm lens f = 0.035 and its diopter strength corresponds to 1/0.035=28.6. Likewise a 50mm lens is 20 diopters and a 100mm lens 10 diopters.
Thus the wide angle lenses are the strong lenses whereas telelenses are weak. Strong lenses give bigger magnification as long as they are placed close to the subject. For the highest of magnifications (as in a microscope) one needs lenses with very short focal lengths, placed very close to the subject. They also need to be very small in diameter. The latest technology of multiple strand optical cables can indeed place the camera at a fly's eye.
 
 

Extension tubes The standard primary (not zoom) lens is extended outward by means of extension tubes which are water tight. There is no standard for such extension tubes, but they usually come in three sizes which can be combined, or one size in combination with lenses of different focal lengths (e.g. 28, 35, 80mm). The picture shown here gives the general idea. It is a commercially available extension tube for Nikonos III, IV, V cameras. The framer is necessary because these cameras have inadequate focusing arrangements. For this kind of bracket one must mount the strobe directly above the camera to avoid one of the side poles casting a visible shadow. When the strobe is placed towards above-left, the lefthand post needs to be sawn off.

The fixed distance extension tube works well, as scientists use it to document nudibranchs and other small creatures. They often carry two Nikonos cameras with extension tubes set for different enlargements. But one is never sure where the camera focuses precisely. Furthermore, subjects often do not tolerate a frame pushed onto them. So, on the one hand one wishes the frame to precisely indicate the plane of focus, but on the other hand one wishes to place the subject just outside the frame.
This can be done to some extent with the lens' internal focus ring which runs from 0.8m to infinity (1.25 diopter). For a standard 35mm lens of 28 diopters, this is but a small change of around 5% in distance. Depth of field follows also along this logic: the larger the magnification, the more critical depth of field becomes.
 
 

Close-up lenses For housed SLR (Single Lens Reflex) cameras, the obvious way to go macro is by placing a close-up lens in front of the primary or zoom lens inside the underwater housing. The following focal distances (in cm) above water now apply:     1D 2D 3D 4D 5D infinity 100 50 33 25 20 1.0m   50 33 25 20 17 0.9m   47 32 24 20 16 0.8m   44 31 24 19 16 0.7m   41 29 23 18 16 0.6m   38 27 21 18 15

To make your own table of focal distances, use the formula: diopter = 1 / s - 1 / c  where c is the camera adjustment from infinity down to wherever, in metres. This translates to: 1 / s = diopter + 1 / c  For underwater distances, multiply by 1.33.

From this table a very clear picture emerges:

• the camera's distance adjustment has the largest effect on the smallest diopter
• with a camera range from 0.5m to infinity and a 1 diopter in front, one can take pictures from 33cm to 100cm.
• when using a strong diopter, it makes no longer sense to use the camera for focusing, and one needs to focus by moving the camera forward and backward.
• a close-up lens takes long distance focusing away.

• it is a cheap way to keep using the expensive primary lenses you already have
• it creates extra space between the front of the lens and the subject, for the strobe light to enter

• it is another lens group, inviting for additional unsharpness
• it may make the camera more clumsy

f034704: mating pigfish (Bodianus unimaculatus) at dusk, showing their mating colours. Shown here is the uncropped image taken with a 50mm macro lens at 2m distance f4, lit by strobe light with a colour correction filter. The picture is sharp. The picture was composed to symbolise how close the fish were to the surface.

f047913: this large parrotfish (70cm) sleeping at night, was taken with a 50mm macro lens from 2.5m distance at f4 and f5.6. The same technique as described on left was used. Note how the fish has solidly wedged itself in place. An interesting detail is that this shallow niche faced the brunt of the waves head-on, but inside it should be tranquil. How do they find these places?

f041324: in this tight closeup of gorgonean polyps, one must focus by moving the camera in and out, often with autofocus disabled. It is important that all items of interest are in the same focal plane.

f046833: extreme closeups reveal a new level of interest like these tiny 8-armed polyps on a fleshy coral. One can often take advantage of side-lighting because there is too little room for frontal lighting.

Illusive depth scale How can you check that where you think or the camera thinks the focal plane is, is indeed where the lens focuses? When working with 8mm lenses and even 5mm wide angle lenses in Super8 cameras, this becomes very critical. One would think that this is easy to check, but without very special instruments, it becomes nearly impossible. One of the problems is that objects nearer by, become enlarged, and thus appear sharper. To overcome this and other problems, I invented the Anthoni optical illusion scale which you can print here (250KB). It is made by a BASIC program of which you find the full description here as part of a chapter on calibrating your lens for unsharpness and depth of field. Essentially this scale has a number of radiating lines that appear parallel. The markings on this scale are such that they appear equally widely spaced over the entire range. Having eliminated these two virtual sharpness effects, the point of focus can now be read accurately. If you want to check whether infinity is indeed in focus, place a 4 diopter closeup lens in front and focus the camera on a point 25cm distant on the depth scale. With this scale (a waterproof version) you can now verify where your macro lenses focus underwater. It is a very handy tool to have and entirely free. This is what it looks like, with red markers at 15, 20, 25cm.  What the camera sees with a wide aperture, enables you to establish the focal point precisely.

For the situation under water, a factor 1.33 should be applied to the lens to subject distances in above table.
 
 

Because of the clumsy size of underwater housings and their ports, there is little or inadequate room to let the strobe light in for near-frontal lighting. As a result, very tight closeups have to make do with side lighting or back lighting. Here is where some small digital cameras inside very compact housings, have an advantage. Also the old Nikonos V with its small 35mm primary lens, offers an advantage. Don't count this 'obsolete' camera out yet, for large and sharp magnifications.

The message here is that you need to alleviate this problem by making adaptations to the hardware. Use a small strobe and special brackets. In macro photography with a macro lens, the strobe is constantly moved outward/inward, left to middle to right, and is often taken off the bracket for side and back lighting and for admitting light into narrow confines.
 
 

strobe distance Because the amount of light is at a  premium, one would be tempted to place the strobe as close as possible to the subject, but this results in large differences in intensity between the nearest and furthest side, and it also makes the background very dark. If one places the strobe too far back, there could be an insufficient amount of light and it all appears to come from a small spot, resulting in harsh lighting with harsh shadows.

The secret is to work with a small strobe, placed back sufficiently to still appear large (some need a diffuser), while lighting nearest and furthest point in the focal plane with the least difference. By pointing the light a little too far to the opposing side, one uses the environment as reflector to bring light in the shadows while also lighting less of the near side. Understandably, when shooting at variable distances, this compromise must be rearranged each time, resulting in constant adjustment of the strobe. How easy you can do this, makes a large difference to your chance of success.
 

The diagram illustrates the effect of a small strobe or a strobe placed backward too far. A small strobe behaves like a point source, creating harsh shapes and shadows because the light cannot reach the sides. A large light source as used to be common with bulb flashes, creates soft blending shadows and gives objects that three-dimensional look. It also makes scatter less obvious. The challenge is to create a large light source which can also be placed nearby. Note that in the drawing the subject is brought closer to the light source to make the light source appear larger, but this of course exacerbates uneven lighting between the near and the far side. What is needed is a larger reflector while keeping the strobe away from the subject. Note that in supermacro photography (linear enlargement larger than 1:1), the strobe must be placed proportionally closer to the subject.

f046627: this tropical whelk (5cm) was photographed with a single strobe placed centrally above. Reflection from the environment brings enough light to soften the shadows.

f046410: this painted crayfish was not easy to reach. A large SB104 strobe casts light around legs and feelers, bringing some light there.

So let's review our options without a second strobe:

• use the environment to reflect light into the shadows. Ironically, the very large and powerful SB104 strobe, designed for wide angle photography, blats so much light all around, that often enough comes back to fill the shadows.
• place the strobe back somewhat so that it produces more even lighting. The strobe's position depends entirely on the size of the focal plane and magnification.
• place a diffuser in front of the strobe to make it appear bigger, preferably also guiding some light to the other side. you must have sufficient flash power to do this.
• make sure your bracket allows you to change the position of the strobe easily, particularly when you have an autofocus macro lens. You must have a modelling light for this. See also the chapter on making your own equipment and Anthoni's unique bracket system. In variable-distance macrophotography, the strobe is constantly adjusted and moved inward and outward.
• where ambient light is still available, place the strobe on the other side and let sunlight fill the shadows. This is often possible because it can be strong enough for minus three f-stops.
• identify the plane in your subject because the strobe needs to light it evenly.
• when you hold a subject in your hand, move the strobe to the other side.
• remember that macro photography is relatively easy, so it needs perfect lighting for best results.

• sidelighting creates a black background against which scatter becomes eminently visible. We must now use a light source with a narrow beam (often blinkered or barn-doored) which can be pointed at the point of focus. You must have a modelling light which points in the beam's direction. The camera must be focused manually, on one's finger for instance. The subject is then placed in the light beam where it is also in focus.
• sidelighting is most successful with a small light source as a harsh effect is desired.
• it helps if your buddy shines on the subject at night, while you prepare your approach
• the same setup can be used in daylight. Make sure an unobstructed sea forms the background.
• have patience, because many adjustments must be made to get it right. When taking photos in mid water, everything seems to work against you. The jellyfish is moving, your bubbles affect it, your buoyancy is hard to control, as is your distance to the subject and so on. Just take time.

f036622: a densely set hydroid tree (Solanderia sp) invited for back-lighting, which was done by the photographer, but a shrub this size could better have been lit by the buddy, holding the strobe further out.

f046112: a comb jellyfish reflected by the water's surface. This stark photo was taken with the sidelighting technique discussed above.

• the glass must be clean and without scratches, which is obvious. The quality of your photo depends on the weakest link.
• reflections must be avoided, which can be done by moving the strobe very close to the glass and out of view of the camera. Also camera angle matters in relation to the position of the strobe.
• one can employ complementary linear polarisers to exclude reflections (explained below)
• a powerful strobe must be used. Often underwater strobes provide more light. The objective is to stop the lens right down to f22 or better.
• an underwater strobe can be placed inside the aquarium, improving quality considerably:
• it gives a more interesting light angle
• sidelighting and backlighting are now possible
• it avoids reflections from the glass but it may upset the subject.
• it provides for the shortest light path, thus retaining more of the red component of the light.
• the light passes through the window only once, thus halving an undesirable colour cast
• one can arrange the light direction such that the other windows become invisible or less visible. Note that an aquarium window becomes a good mirror from the inside looking out. A light placed high thus reflects on the other sides, unless placed above the aquarium, but this gives an unnatural light.
• normal lenses, however expensive, do not correct for the air-water interface and a Nikonos RS underwater camera gives best aquarium shots with its 50mm macro lens.

f032018: a 4cm transparent shrimp (Palaemon affinis) photographed through aquarium glass with a Nikonos RS underwater camera outside and a small strobe inside. This gives best results.

f016731: in the fish market we could demonstrate how John dories can extend their mouths to catch fish. Two complementary polarisers were used to eliminate glare. This technique is also suitable for medical photography.