Macro flash

Artificial light used in nature photography looks unnatural because this kind of light is, in fact, not natural at all. The natural light we use to illuminate subjects comes in two forms and two forms only: sunlight and diffused, ambient light. Even if we use moonlight, this is simply the sun’s reflected light off the lunar surface.

We use artificial light when photographing nature for three reasons: 1) The subject is dimly lit and we need the additional light to insure a sharp picture. Or we want to increase the depth of field as in the picture of the frog, below; 2) we want to create dramatic lighting as I did in the shot of the seashell on the next page in which the flash was placed directly behind the shell for backlighting; and 3) we use the brief flash duration (the actual length of time the light inside the flash is on during the exposure) to freeze movement. This may be necessary because of the low level of light as well as when the subject is moving too fast for even a super fast shutter to freeze. Hummingbirds are an example. The flash duration used for the green crowned brilliant hummer on the next page was 16,000th of a second, and that completely froze the wings.

Macro photography requires flash if there is any possibility the subject could move, even slightly. A gentle breeze, the tentative step of an insect, the flutter of a wing -- all of these things render images unsharp. Most macro shots require small lens apertures to offset the loss in depth of field due to significant magnification inherent in photographing small subjects, and that means shutter speeds are relatively long. This, in turn, means a flash is necessary to freeze unwanted movement in the subject.

Macro flash options

There are three types of flash units practical for macro photography: 1) A ring flash, 2) a twin flash setup, and 3) a typical hotshoe mounted portable flash. I don’t include studio flash units with softboxes or umbrellas because most macro photography is done in the field. But even if you shoot small subjects indoors, studio equipment is too large and unwiedy for macro work.

I also don’t recommend portable flash units like the Canon 600EX or the Nikon SB500. Macro photography means almost by defintion the camera and lens will be very close to small subjects. Portable flash units sitting in the hotshoe of the camera will illuminate the

top of the subject, but the underside is often left in shadow. In addition, direct and harsh front lighting isn’t very attractive. Only if the portable flash is used off to the side -- i.e., offcamera -- is it effective, but that leaves you with only one hand to manage the camera because you’re holding the flash with the other hand.

So that leaves two sensible options: A ring flash, pictured at upper right, and a twin flash macro setup pictured at lower right. Here are the pros and cons of choosing one of these over the other.

1. Many ring flashes are significantly less expensive than a twin flash setup.

2. A ring flash is more compact; the twin flash setup sticks out from either side of the camera. When shooting insects, small frogs, butterflies, etc., the two flash units may interact with leaves and twigs and the light could be partially blocked.

3. The ring flash simulates diffused daylight while the light from the twin flash setup is more direct, i.e., somewhat harsher.

4. You can get a better defined light ratio from the twin flash setup. While a light ratio can be selected in the ring flash, it won’t be as defined. A light ratio means you can make one side of the image lighter than the other side.

You can purchase third party ring flash units for less than $100 now. They won’t be as powerful as, say, a Canon ring flash, but with the ability to raise the ISO without incurring too much noise, this is less of an issue than it used to be. My preferred lighting equipment for macro flash is a ring flash. units. You can buy a ‘ring flash’, and you can also get a ‘ring light’. The latter isn’t a flash at all. With bright LED’s, it provides the same kind of light as the ring flash but it’s much less powerful. It looks good to your eye, but it means you won’t be able to use small lens apertures like f/22 and f/32 because there just isn’t enough light (unless you raise the ISO to 12,800 or more). This is a problem. Therefore, don’t buy an LED ring light. Instead, get the ring flash.

Camera settings

For either a ring flash or the twin flash setup, the settings I recommend are:

Carnival in Venice

February 12 - 18, 2023

-- The shutter speed should be the sync speed or slower. I typically use 1/200.

-- F/22 or f/32. It’s true that these small lens apertures cause diffraction and a slight loss in image quality. But they provide more depth of field than larger f/stops, and with macro work that’s critical. Macro photography is all about detail; the ideal is to have the subject as sharp as possible. Focus stacking at f/8 is the best case scenario for sharp pictures, but with so many subjects, like frogs and caterpillars, the likelyhood of zero movement during a focus stacking sequence of shots is small. That means small apertures are essential, and that’s why I take almost all of my macro pictures at f/32.

-- Use an ISO setting anywhere between 200 and 800. Or, use auto ISO. Judge exposures on the LCD and tweak them as needed.

-- Autofocus can be turned on or off, depending on the magnification. With extreme magnification, like the foot of the frog, above, I turn the AF off and focus by moving the camera back and forth. This turns out to be easier for me. §

Previous page: Note the ventral surface of the frog is illuminated with virtually no shadows on the frog’s skin. This lighting comes from a ring flash. Above: I shot this caterpillar with a twin flash setup using a light ratio in which the left side is brighter than the right side.