Magnifying past a 1:1 image ratio of your subject is commonly referred to as going from macro photography to super macro photography. Super macro is a challenging but rewarding subsegment of underwater photography.
A standard macro takes a subject you can see pretty well with the naked eye, and brings out detail, color, and translucence that you had no idea was there unless you had seen in an image before. Super macro often deals with subjects that you can barely discern with your eye. The details revealed in a well exposed capture are stunning, and addictive.
Super macro photography is challenging due to the narrow depth of field and the very close working distances. Shooters working on super macro images are notorious for being the worst dive buddies, preferring to concentrate on the smallest section of reef, and seldom moving.
There are many approaches. Most require lots of light so we can stop down our lens for maximum depth of field.
For DSLR users, the most popular lens choices are:
- Canon EF 100mm f/2.8L IS USM Macro
- Nikon 105mm f/2.8G EF-ID VR Macro
- Sony FE 90mm f/2.8 G OSS Macro
- Sigma 105mm f/2.8 EX DG OS HSM Macro
- Canon EF-S 60mm f/2.8 Macro (crop sensor cameras only)
- Nikon AF 60mm f/2.8G ED Macro (crop sensor cameras only)
Then you add external magnifying lenses or diopters to allow closer focusing and greater magnification. These diopters can be screwed onto the lens itself, but more popular are the external wet lenses that can be attached to the end of your flat port.
A diopter is referenced by a + number which indicates its strength, i.e. +5, +10, etc. The greater the number, the greater the magnification. Most macro wet lenses can also be stacked for greater magnification. Examples are the INON UCL-165, ReefNet SubSee Magnifier, and the SAGA Diopter Close-Up Macro Lens.
Be prepared: it’s much harder than macro.
Often center spot focus is the way to go for super macro. Your depth of field is so narrow you have to choose what is going to be sharp, and what you choose is key.
Autofocus is fantastic for macro photography but can be maddening for super macro as it struggles and continuously searches. There are a few ways to avoid this:
- Use manual focus (MF).
- Use the back button focus technique to lock focus, then get your subject properly in frame and shoot.
- Switch to MF and lock the lens in minimum focus before you install it in the housing. This means you will ultimately always shoot at the same distance.
Regardless of the way you lock focus, most often you will rock the camera in and out of the focus plane and shoot when the focus is on the most important part of the subject.
A Different Approach
It is a happy coincidence that much of the new technology in compact and mirrorless cameras lends itself so well to super macro shooting.
Microscope mode like on the Olympus Tough TG-5 compact camera means super macro right out of the box. The magnifications rival anything that can be done with the previous systems discussed here.
Many of us will want to shoot the smallest aperture we can muster (highest f/number) to battle the razor thin depth of field. But the assumption that f/22 is better than f/8 is being challenged these days. Some contend that each lens has a “sweet spot” in its aperture range.
The important thing to keep in mind is that you will have only one thing in focus... choose it well. Everything else will be “bokeh” which means it is out of focus on purpose.
Lighting Your Subject
There are still more challenges. One is light. We need a lot in a very small area. Most any flash is powerful enough, but the placement of your light can be tricky.
Super macro lenses and particularly microscope modes typically require the subject to be “right on the lens” (but don't actually touch it). You may need a longer strobe arm to get the flash very close to the front of the lens and the subject. Often you will need to light from a top-down angle.
Automatic TTL exposure is preferred for strobe light so that you don't blow out the subject and you can focus on.. well.. focus.
A simple solution is to use a constant-on video or dive light. We are capturing such a small area that the power (lumens rating) needed is minimal.
The advantage is that your camera will see, and use this light. It will focus faster, and stop down its lens (if shooting in an automatic exposure mode).
The disadvantage, particularly with very bright lights, is the heat radiated. You can feel it at very close distances, and so will your subjects. If you are night diving often the “bugs” will come out and follow you and dance in your frame. Lionfish and other predators will even use your bright light to hunt.
Ring lights are famous for macro work. The major advantage is the ability to light your subject consistently while maintaining a very short working distance (without touching). The criticism is that too much uniformity in your light, i.e. not enough shadowing, can leave your subject looking flat and lifeless. This downside is probably overstated given the major advantages in ease of use.
Focus Stacking: the Holy Grail?
There is a post-capture solution to depth of field at this level. Very little is being done with it currently, but as it's now being built into some cameras we expect to see more.
Simply put, you would capture a number of images of the same static subject, but changing the focus slightly for each frame. Then use software to combine these frames so all parts are sharp. The Olympus Tough TG-5 has this built in, and can rattle the frames off so quickly that hand holding is possible.
Keep a close eye on your dive computer because it's easy to get sucked into the world of super macro and lose sight on everything else. It will take a lot of patience and practice to get the right shot. Don't give up... super macro images can be astoundingly beautiful and worth the effort!