Macro and close-up nature photography

Some of the most surprising nature photographs show the small world: the compound eye of a dragonfly, dew drops on a spider's web, the gills of a mushroom, frost crystals on a window or the structure of a wildflower. Macro and close-up photography reveals details invisible at normal viewing distances and can be practised in a backyard, a city park or a forest edge. This lesson applies the close-up optics introduced in PHOT-310 for products to living subjects outdoors: magnification and working distance, equipment options, the very shallow depth of field at high magnification, focus stacking in the field, light and flash, wind, and the ethics of photographing insects, plants and fungi without harming them.

Magnification and what counts as macro

Magnification is the ratio of the size of the subject's image on the sensor to its real size. A 1:1 ratio, or 1×, means a 10 mm insect makes a 10 mm image on the sensor; on a full-frame sensor 36 mm wide, it fills just over a quarter of the width. True macro photography usually means magnifications of about 1:2 (0.5×) to 1:1 or more; anything less is close-up photography. Some specialized lenses reach 2× to 5×.

The field of view at magnification \( m \) on a sensor of width \( w \) is simply \( w / m \). At 1:1 on full frame, the frame covers 36 × 24 mm; at 0.5×, 72 × 48 mm; at 2×, 18 × 12 mm.

Equipment options

Several tools give close-focus capability, each with trade-offs:

• Dedicated macro lenses, typically 60, 90 to 105, or 150 to 200 mm, focus to 1:1 with excellent sharpness. Longer focal lengths give more working distance, which matters for skittish insects and for avoiding shadows from the camera.
• Extension tubes are hollow spacers between camera and lens that let any lens focus closer. Extension \( e \) on a lens of focal length \( f \) focused at infinity gives magnification of about \( m = e / f \). They contain no glass, so they do not reduce sharpness, but they cost light.
• Close-up lenses, also called diopters, screw onto the front of a lens like a filter and reduce its focusing distance. Good two-element versions work well on telephoto zooms, giving close-ups with useful working distance.
• Reversing a lens, mounting a wide or standard lens backwards with an adapter, gives high magnification cheaply but with no automatic aperture or autofocus.
• Specialized high-magnification lenses reach 2× to 5× or more for very small subjects, at the cost of tiny depth of field and working distance.

Working distance

Working distance is the space between the front of the lens and the subject. At the same magnification, longer lenses give more working distance. For a simple thin lens, the distance from lens to subject at magnification \( m \) is about \( f(1 + 1/m) \), as PHOT-310 showed for products; real macro lenses use internal focusing and complex designs, so their actual working distances differ, but the principle holds.

More working distance helps with insects that flee when approached, keeps the camera's shadow off the subject and makes room for light modifiers. Longer lenses also have a narrower angle of view, so they show less background, which helps simplify busy scenes.

Depth of field at macro distances

At high magnification, depth of field becomes tiny. A useful approximation for total depth of field \( D \) at magnification \( m \), f-number \( N \) and circle of confusion \( c \) is:

At macro distances, depth of field depends on magnification and aperture, but hardly at all on focal length: a 60 mm and a 180 mm lens at the same magnification and f-number give nearly the same depth.

The effective aperture also changes at close focus. As a lens moves away from the sensor to focus closer, less light reaches the sensor; the effective f-number is about \( N(1 + m) \), so a lens set to f/8 behaves like f/16 at 1:1. Most modern cameras report and meter this automatically, but it matters for diffraction: at 1:1, f/16 has the diffraction of about f/32, which is very soft on high-resolution sensors. Many macro photographers work at f/8 to f/11 and stack.

Placing the plane of focus

With so little depth to work with, where you put it matters more than how much you have. For insects, the eye should almost always be sharp. Aligning the sensor parallel to the main plane of the subject, such as the side of a butterfly's wings or the face of a flower, puts more of it in focus at once. Moving the whole camera slightly forward and back, rather than turning the focus ring, is often the easiest way to fine-tune focus at high magnification; a focusing rail on a tripod makes this precise.

Focus stacking in the field

Focus stacking, introduced in Lesson 4, is standard in macro. The number of frames depends on the depth of the subject and the depth of field per frame. With frames overlapping by about a quarter, each frame advances about three quarters of its depth of field.

Field stacking works best on subjects that do not move: fungi, lichens, flowers on calm days, frost and resting insects at dawn when they are too cold to fly. Wind is the enemy. A plant clamp, a windbreak made from a jacket or a portable reflector, and patience help. Some cameras can shoot rapid focus brackets of dozens of frames in a second or two, which handles slight movement.

Light for macro

Small subjects need a lot of light to shoot at fast shutter speeds and small apertures. Natural light works well on overcast days or with a diffuser held between the sun and the subject, which softens harsh shadows. A small reflector can fill shadows. Backlight makes translucent petals, leaves and insect wings glow.

Flash is widely used in macro. A small flash, a ring flash or twin flash on the lens, or a flash with a large diffuser close to the subject, freezes motion and allows small apertures. Because the subject is close, a small diffused flash acts as a relatively large, soft light source. Flash can produce black backgrounds if the background is far away and receives little light; to avoid this, balance flash with ambient light using a slower shutter speed or higher ISO, or place a natural background closer.

Subjects through the seasons

Macro subjects change with the seasons in temperate regions. Spring brings emerging leaves, early flowers and the first insects; summer is peak season for insects, spiders and wildflowers; autumn offers fungi, seed heads, dew and spider webs; winter brings frost, ice crystals, snowflakes and lichens. Dew-covered insects at dawn and frost patterns on cold mornings are classic subjects that reward early starts. Water droplets on leaves and webs act as tiny lenses that reflect or refract the scene behind.

Ethics of macro nature photography

Small creatures deserve the same respect as large ones. Common practices that harm subjects include chilling insects in refrigerators or freezers to slow them down, gluing or pinning live insects, moving animals to better backgrounds, breaking stems or pulling plants for a cleaner composition, damaging fungi or lichens, and trampling vegetation around a rare plant. Photographers increasingly reject these practices, and many competitions require disclosure of captive or manipulated subjects (Lesson 12).

Good practice includes photographing subjects where they are, at their own pace; using natural behaviour such as cold early-morning stillness instead of artificial chilling; holding stems aside gently with a clamp rather than breaking them; staying on paths near sensitive plants; and avoiding disturbance of nests, burrows and egg masses. Rare plants and insects may be legally protected under species-at-risk laws, discussed in Lesson 10; even photographing them can require care about sharing locations, because collectors and crowds may follow.

Some photographers keep insects briefly in a container to photograph them in a controlled setting and then release them where found. This can be done humanely, but it should be disclosed when the image is presented as natural behaviour.