Why Rainbow Photographs Go Wrong

Make a reference frame first

Use the focal length already mounted and the camera's initial meter reading. Record RAW as well if available, then check highlight warnings or the histogram rather than trusting the rear-screen impression alone.

This frame does not need to be finished. Exposure changes or a polarizer can make the bow weaker. With a fast-changing subject, a reference is safer than beginning with an elaborate setup.

Look opposite the Sun

NOAA explains that the red edge of a primary rainbow appears about 42 degrees from the antisolar point. A secondary bow results from a second internal reflection, appears farther out near 50 degrees, and reverses the order of its colors.

That geometry gives one practical instruction: look away from the Sun. As the Sun rises, the visible arc sits lower; closer to sunrise or sunset, it can rise higher.

Geometry does not determine how saturated the bow will look. Droplet size, rainfall, cloud background, and sunlight all change it. The secondary is fainter, but its brightness relative to the primary should not be treated as a fixed exposure ratio.

Expose for the picture you want to keep

Darkening the sky can make a rainbow easier to see, but negative compensation is not universally correct. If a dark street or person matters, metering only for the bow can bury the ground.

Start with the standard exposure, then change compensation in small steps. Check whether bright cloud has clipped and whether useful foreground information remains. Let the histogram and subject decide, not a universal “−1 to −2 EV” rule.

If sky and ground are far apart, make several frames at different exposures. You can decide later whether to blend them or choose one. Automatic HDR can misalign a changing rainbow, so inspect the result closely.

Use a CPL by watching its effect

Nikon notes that a polarizer can reduce reflections, increase saturation, and sometimes make a rainbow more visible, while costing roughly 1.5–2 stops of light.

Rainbow light is polarized, so rotating a CPL can strengthen or weaken the bow. Watch the finder or live view while turning it and balance the bow against the foreground. Remove it if the effect is weak, it costs a needed shutter speed, or the rainbow fades.

Choose the whole arc or one contact point

A primary bow is part of a large circle, so including the full arc requires a wide view. It may then become one element in a broader landscape. A longer lens can isolate a root of the bow or the border between rain and cloud.

Neither choice is inherently stronger. One records the complete event; the other asks where the rainbow touches the place. With a double rainbow, it is reasonable to make one evidential frame of both and another that concentrates on color or context.

Leave room to decide the color later

After rain, warm direct sunlight and cool cloud light may occupy the same frame. One white-balance value cannot make both perfectly neutral.

RAW preserves room to decide later how much of the cool rain and returning warmth to keep. With JPEG, try Auto and Daylight as a comparison. Do not treat one Kelvin value as a universal starting point.

Judgment

The useful order is short:

1. Make a reference frame while the rainbow is visible.
2. Read its position opposite the Sun.
3. Decide whether the sky or the ground carries the picture.
4. Change exposure and polarization one step at a time.
5. Separate a record of the whole event from a photograph of one chosen part.

A rainbow cannot be manufactured by settings. What remains under your control is what you preserve first and how far you intervene while the conditions change.

Sources

• NOAA NESDIS: What Causes a Rainbow? — primary and secondary bow angles, reflection, and color order (checked July 29, 2026).
• Nikon: Polarizing Filters Add POW to Pictures — polarizer effects and light loss (checked July 29, 2026).