Most of us have been intrigued at some point by things we cannot see with the naked eye. Scientists are continuously making new discoveries in the oceans, and underwater photographers are keeping pace by documenting the large and very small elements that make up our oceans. In my view, there are two developments in the last 15 years that have helped spur the growth in underwater super macro photography to the level we see today:

1. The availability of digital cameras. Being freed from the limits of film and having the luxury to instantly review images, photographers now have the latitude to attempt shots at higher magnifications.

1. The continual discovery of really tiny marine species. Although the Bargibanti Pygmy Seahorse was first discovered in 1969, six more species have been discovered since 2000 and have become the darling of underwater photographers since.

The almost insatiable thirst for greater detail while shooting underwater has spurred the development of waterproof macro lenses, or wet diopters, with ever increasing magnification capabilities. There are now many brands of wet diopters with varying magnifying strengths on the market. Inon was one of the pioneers and now others like ReefNet Subsee, Dyron, F.I.T. and Nauticam have become popular choices. They range in strengths from +5 to +16 when used on land, but their true magnifications are often greatly reduced when deployed underwater.

Filling the frame with a pygmy seahorse, which on average is about 2cm long, can now be achieved with a wet diopter. The challenge now is to obtain higher magnifications to capture even more detail (for example, a facial portrait of a pygmy seahorse). So what is the easiest way to increase magnification? Stack diopters on top of one another!

Stacking Macro Lenses on Compact Cameras

Many compact cameras are designed and marketed with macro photography in mind,  providing focusing capability as close as one centimeter from the subject.

In photography, a lens is considered to have macro capabilities if it can shoot a subject at a minimum reproduction ratio of 1:1, which means the true size of the subject is reflected on the photograph. In other words, if the subject you are capturing is 20mm long and the image sensor in your camera is also 20mm in length, then the subject taken should totally fill the length of the resulting photograph.

This is not possible in compact cameras. For instance, my G12 has a maximum reproduction ratio of 1:4, which infers that I can only capture subjects at a quarter of its actual size on my photos. With my G12 totally zoomed in to its longest focal length I only get a reproduction ratio of 1:11, not to mention a minimum focus distance of 30cm! Because of this, compact cameras will benefit greatly from stacking diopters.

PROS

• Compact camera users can capture macro shots with a macro diopter, and super macro shots by adding a second diopter. The first diopter added should take a compact camera very close to the magical 1:1 reproduction ratio. The next one will bring you to more than 1:1 for super macro shots. For example, using Reefnet's Magnification Calculator, when a +10 diopter is added to a G12 at its longest focal length the reproduction ratio improves to 1.1:1, which is right in the macro range. Adding another +7 diopter improves it to 1.9:1, within super macro territory.

• To achieve the greatest magnification the compact camera has to be fully zoomed in while the diopters are attached. Attaching diopters while at the widest setting will cause substantial vignetting.

• Closer working distances with diopters also means there is less water between the lens and the subject, reducing the risk of getting backscatter in your photos.

• The LCD screens on compact cameras tend to show a deeper Depth of Field (DOF) than the viewfinders of DSLR cameras, making focusing much less of a challenge comparatively. Some camera models even come with a focus assist function, where the area over the focus point is enlarged even further on screen, allowing for better fine-tuning.

• The smaller sensors used on compact cameras create greater DOF compared to DSLRs, so more of the image will be in focus, even with diopters.

CONS

• If you thought focusing with one diopter lens was challenging, adding another further compounds the difficulty. It takes more time and patience to achieve sharp focus with stacked diopters than before. Practicing good buoyancy and learning to stay still while capturing the shot are separate challenges in themselves.

• Stacking diopters greatly decreases the depth of field of the image. Compact cameras usually have their smallest apertures between f8 – f11, which after stacking diopters means the DOF of the photo could be much shallower than you'd expect. So order to have a usable photograph, care must taken to choose the area of the subject to focus on. This can be used to your advantage, however, by achieving focus on parts of the subject to which you want to draw attention (like the eyes).

• The much closer focus distance means that if you are using strobes, you may need to position your strobes further forward and closer to the camera. A good starting position is with your strobes close to the front edge of the outmost stacked diopter, angling the strobe face away from the subject.

Stacking Macro Lenses on DSLR Cameras

Capturing tiny subjects with DSLRs proves relatively simple with dedicated macro lenses that attain a 1:1 reproduction ratio. A diopter isn’t needed to achieve this ratio, and when used, immediately take subjects into the super macro realm.

PROS

• You can achieve truly large magnifications. If I stack both my Subsee +10 and Dyron +7 diopters with a 105mm macro lens, the combination yields a reproduction ratio of 3.2:1, meaning I can take subjects as small as 8mm and fill the frame.

• The focus distance will be very close, so backscatter will be less of an issue. In fact, at such huge magnifications the little particles that cause backscatter might actually show up clearly and in focus as part of the photo!

CONS

• Stacking diopters works best for macro lenses with longer focal lengths (100mm and above), as they have minimum focus distances that are further away from the subject, providing more space for stacking diopters. Lenses with shorter focal lengths (like 60mm) have very close working distances, leaving little space to add any diopters. If you have been using 60mm lenses exclusively, you may have to think of investing in a new macro lens and the corresponding ports.

• A close focusing distance can be a double-edged sword. Stacking diopters on a DSLR means focusing distances so close that it may be hard to illuminate your subjects with your strobes. Using the combination mentioned above I found myself focusing at around one centimeter, and I had to be very careful and creative in placing my strobes to light up the scene.

• Depth of Field will be very shallow, so very small apertures (as high as f/32) may be needed to create the DOF needed to have all of your subject in focus. Using such small apertures also means sharpness will be compromised due to diffraction.

• Modern DSLRs leave the aperture blades wide open before taking a photo to keep the viewfinder bright, stopping down to the required aperture only when capturing the image. The resulting picture on the viewfinder will look like you are capturing the image at the widest aperture of the macro lens, usually f2.8. This, combined with the razor thin focal plane of stacked diopters, makes achieving sharp focus challenging.

• Such shallow DOFs make autofocus perform very slowly. It may be more effective to use manual focus instead, rocking the camera (ever so slighty) back and forth and pressing the shutter when the photographer can tell that the subject is in focus. This can take many attempts and some time.

Shooting Tips with Stacked Diopters

Here are some suggestions to improve your chances of success when shooting with multiple diopters:

• Look for subjects that tend not to move. The less they move the easier it is for you to focus. Corals are the perfect starting point.

• Make sure to find a relatively stable and relaxed position that does not damage to your surroundings when attempting the shot. It tends to take a substantial amount of time to achieve the shot desired, so you better get comfortable.

• Use a focus light whenever possible to help achieve focus. It is hard enough to focus with such thin DOFs. A focus light will greatly help your autofocus system.

• The subjects chosen when stacking diopters tend to be very small and thus fragile. Always ensure the well-being of the subject during the photo taking process, as it can be easy to touch them with the front of the diopter.

Is It Worth The Hassle?

It might seem that stacking diopters is more trouble than it is worth. The difficulty lies in achieving sharp focus regardless of camera style, and this takes up precious bottom time. It does make one wonder if it is worthwhile to invest time and effort to get that one shot of a subject so small and seemingly insignificant, especially when other dive buddies are snapping away happily at many other wonderful creatures at more 'manageable' sizes?

The happy truth is that, if one can get comfortable with super macro photography, it actually opens up a plethora of opportunities to take wonderful photos. Whales, sharks and other pelagic fish may continue to steal the limelight, but at the other end of the scale there are unique textures and details that are no less fascinating. With a little creative composition, subjects that seem run-of-the-mill can be transformed into amazing images with that special WOW factor. Gone are the days when you “see nothing” on a dive, because with a keen eye one may spot a small scene worth stacking the glass to shoot. A boring dive? Never again.

Further Reading

• Alor: Indonesia's Secret Gem

• Nikon D600 and Sea&Sea Housing Review

• Super Macro Photography Underwater