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Macro photography, simply put, is any photography where the reproduction
ratio is 1:3 or greater (i.e. 1:3, 1:2, 1:1, 2:1, etc). The reproduction ratio
is the ratio of the size of the subject to the size of the image on film. 1:3
means "one third life size." So macro photography at 1:3 means that a
1-inch shrimp is 1/3 of an inch on film. Since the 35mm frame is roughly 1 inch
by 1.5 inches in size, a 1:3 repro ratio means that the largest subject you can
shoot it ~ 4.5 inches across...but mostly, when people use the word
"macro" they're thinking of smaller subjects, things an inch in size
Macro is generally one of the easiest styles of underwater photography because
lighting is easier, framing is easy to do, and (for Nikonos users) the focus is
fixed. There are really only a couple of variables the photographer needs to
|Housed camera: any macro lens (60/90/105/200mm)
Nikonos: 28 or 35mm lens with extension tube & framer
Snapshot cameras: Macro kit with framer
|50 W-s strobes will do fine; look for a guide number of 28
Coverage angle unimportant. Diffusers can be helpful, but are not
|f/16 - f/64
|TTL flash OK?
Here are the things you need to known when shooting macro.
First off, you can usually set your strobe on TTL and forget it after that.
The main rule of composition with macro is to fill as much of the frame as
possible with your subject. This is the perfect situation for TTL flash control.
About the only thing you have to control carefully with macro pictures is the
aperture. The reason is that depth of field diminishes with increasing
magnification. At high magnifications (i.e. "macro"), the depth of
field is tiny -- often as little as a quarter or even an eighth of an inch (7 or
3 mm!) To get even that much DOF, you need tiny apertures. f/16 is about the
widest aperture you can use, and that's probably useful only with 1:3 macro. At
1:1, you'll definitely want f/32, f/44 or even f/64.
"But wait," you say, "my lens only goes to f/32 !" Read
There's one effect you do have to account for with macro photos, called the bellows
effect. Basically, if you're shooting macro you're going to extend the lens
extra-far in order to get macro-style reproduction ratios. If you're shooting
with a Nikonos rig, you use an extension tube to move the lens away from the
camera body. If you're shooting a housed system with a macro lens, your macro
lens will automatically extend itself...either way, you have increased the
effective focal length of the lens in the process. For the same aperture
setting, a longer focal length means a smaller effective aperture! Read digression
#1 from Exposure 101 if you want to know why all of this is true.
So if you're using a Nikonos 35mm lens and a 1:1 extension tube, even though
you have the lens set on f/32, its actual or "effective"
aperture is f/64! If you have a housed modern SLR, you probably don't need to
worry about this, because the camera and lens are programmed to display the
effective aperture rather than the one indicated on the lens. However, this can
be misleading if you dial in your aperture while the lens is extended. For macro
in housings, you're best off setting the aperture to the desired value at the
start of the dive, while the lens is focussed on infinity, and then not touching
if afterwards, regardless of what the camera tells you the effective aperture
So what? If you're shooting TTL flash, the camera will let the flash run as
long as it wants, regardless. The only reason you need to know the effective
aperture is so you can figure out if your strobe is powerful enough. Review the Guide
Number Equation if you're unfamiliar with it, because we're going to use it
Let's say you're shooting 1:1 at an indicated f/16, which converts to f/32.
Then if the strobe is placed 1 foot from the subject, the guide number equation
tells you that you need a strobe with
GN = aperture * distance = 32 *
1 foot = 32 for ISO 100 film. That's no major problem.
However, if you're shooting ISO 50 film (like Fuji Velvia, for instance), you
have to divide that GN by 0.71, so you'd need a strobe of guide number 45.
That's a hugely powerful strobe! Now you have a problem, and you have one
of two solutions available to you. Let's say you're shooting an Ikelite
SubStrobe 50, which has a guide number of 28. If you move the strobe in so that
it's 6 inches from the subject, the equation looks like this:
GN = aperture * distance = 32 *
0.5 feet = 16 for ISO 100 film, or 22 for ISO 50 film.
The SS-50's guide number is 28, which is greater than 22, so you're OK. You
could probably move the strobe out to 8 inches and still be OK.
Another solution is to use two strobes. If you put both of them on-target,
you get twice the light that you'd get from one strobe. Twice the light means
1.4x the guide number, so two SS-50 strobes on target deliver an effective guide
number of 1.4 * 28 = 39. That's not quite enough to deliver the GN 45 punch we
need for ISO 50 film an a strobe-to-subject distance of 1 foot, but it's much
closer. Moving the strobes in just a couple of inches is an easy way to fix this
So now you see why most macro photographers shoot dual strobes: it makes the
lighting much easier. In addition, two strobes reduce harsh shadows, which
can be an important thing for good macro results.
There is one thing you have to keep in mind when shooting macro with tiny
apertures. Tiny apertures will make your background go completely black if it's
water back there. Basically, tiny apertures make the strobe overpower the
ambient light (unless you run ridiculously long shutter speeds, which really
isn't an option most of the time). So anything that's not lighted with strobe
light (like water) will be seriously dark, often completely black. Sometimes
that's a great effect, but sometimes it's not. When shooting at an effective
f/45 or f/64, remember to think about what's behind your subject, and whether
you would prefer a black background or something colored. Shooting small
subjects sitting on a coral head or a sponge is a great way to get a colored
background. It also adds some context for the person looking at the picture,
which is hardly ever a bad thing.
Macro with black background
Macro with a colored background
OK, enough technical talk. What about composition?
Composition for macro shots is usually very easy. Fill the frame with your
subject, and you're ready to rock. If you're shooting a Nikonos system, your
framing choice will be made for you, because you're stuck at one focal distance
and hence one field of view. The only way you can change the subject's size in
the frame is to pick a different subject. But don't give up on subjects that are
too small in the frame; as mentioned above, having some contextual information
in the background is often a good thing. Also, you can always crop the photo to
About the only thing you have to look out for with macro photos is too-linear
composition. That is, if you shoot a subject head-on in the center of the frame,
it's going to be a boring photograph. You'll get better results if you try to
find an interesting angle, either from above, the side, or below the subject. If
you can orient your subject diagonally across the frame, you'll get a much more
pleasing picture. There's another benefit to diagonal compositions in this case:
you can fit a larger subject in the frame! If you're shooting a housed system,
try orienting diagonally and moving in closer to the subject!
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