How to Reveal the Ozone Blue Band in a Partial Lunar Eclipse Without HDR

What Is the Ozone Blue Band?

During a lunar eclipse, sunlight passes through Earth’s atmosphere before reaching the Moon. At the very edge of Earth’s shadow, shorter blue wavelengths are scattered by ozone in the upper atmosphere, creating a faint bluish fringe. This is known as the ozone blue band—a subtle detail often only seen in well-exposed photographs of partial eclipses.

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Why HDR Makes It Easier

Capturing both the bright illuminated side of the Moon and the shadowed side during partial phases is difficult because of the extreme brightness difference.

• With HDR (bracketing exposures): You can shoot one frame for the bright section and one for the shadow, then combine them. This almost guarantees the ozone band will be recorded.
• Without HDR: A single exposure must capture enough information from both bright and dark regions, which is much harder.

In my case, I took over 1,000 frames during the September 8, 2025 eclipse. Only one image contained usable data for the ozone band. This shows how rare a good single frame can be.

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Shooting Considerations for Single Exposures

To improve your chances of recording the ozone band without HDR:

• Allow slight overexposure of the bright side of the Moon.
• Preserve faint shadow detail on the dark side. Even if it looks underexposed, as long as data is captured, it can be recovered later.

This balance increases the possibility that the ozone band will survive in the RAW file.

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Post-Processing Workflow (Lightroom + Photoshop)

Step 1 – Initial Check in Lightroom

• Push Exposure +2 stops to see if faint blue is present.
• Reduce Highlights slightly.
• If you can see even a faint trace of blue, the image can be developed further.

Step 2 – Channel Work in Photoshop

• Open the file in Photoshop.
• Go to Channels and duplicate the Blue channel.
• Use Ctrl + L (Levels) to stretch the blue channel and reveal hidden data.
• Ctrl + click the duplicated channel to select the blue information.

Step 3 – Targeted Color Enhancement

• Create a Curves adjustment layer with the blue channel selection active.
• Increase blue slightly, reduce red a little to emphasize the ozone band.
• Mask out areas that are not part of the ozone fringe with a brush for precision.

Step 4 – Final Refinements

• Open Camera Raw Filter for global adjustments:
  • Increase contrast to give the Moon more definition.
  • Boost saturation moderately to bring out the blue fringe.
  • Apply sharpening carefully.

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Reflection

Processing a single frame to reveal the ozone blue band is possible, but highly unreliable. Out of more than a thousand shots I took during the September 8, 2025 eclipse, only one contained usable data. This makes it clear that relying on luck is not a sustainable method.

The real lesson is about planning ahead. The ozone blue band sits right at the edge of extreme contrast between bright and dark regions, which means single exposures are almost never sufficient. A carefully prepared HDR strategy—with exposures targeted separately at the bright limb and the umbra—is the practical solution.