Supervisual Photography

Visual Eclipse
Supervisual Eclipse
Visual Image
Supervisual Image
 

 

One of the greatest challenges of photographing the cosmos — and one of its greatest rewards — is to image objects that are difficult or impossible to see with just our eyes. Most astronomical objects are too dim, too far away, or too bright for us to visualize or photograph easily; and to meet these challenges, astronomers and imaging scientists have developed sophisticated techniques and technologies that extend photography well beyond the normal limits of human vision. This kind of photography I call supervisual photography.

To illustrate the power of supervisual photography, the slider above displays two of my images of the 2017 solar eclipse. The Visual Image closely resembles how the eclipse appeared to the eye during totality, while the Supervisual Image reveals details of the lunar surface and the solar corona that were present during totality but were far too dim to see. It’s important to note that the colors are natural and nothing was added or altered to create this extraordinary photo. Supervisual imaging techniques were applied during imaging and processing to tease out these existing features.

Supervisual imaging methods can also help bring to light deep-sky objects that are too dim to see at all. Such images can take hours or days to shoot before processing them. The resulting photos, however, are well worth the effort, revealing a kaleidoscope of colorful stars and vibrant, neon-like nebulae more breathtaking than anything that could be gleaned by the human eye through even the largest of telescopes.

Supervisual photography captures the jaw-dropping subtleties of the world that exists beyond our vision, a spectacular world that we otherwise could never see to appreciate.

The Lagoon Nebula in H-Alpha

The Lagoon Nebula

This image of the Lagoon Nebula was shot from Los Angeles with a DSLR in H-alpha light.

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  • Telescope: Stellarvue SVA130T-IS
  • Mount: Losmandy G-11 with Gemini 2 controller
  • Autoguiding: Yes
  • Optical Configuration: 0.72x field flattener & reducer (f/5)
  • Filter: 12-nm narrowband H-alpha
  • Camera: Canon 60Da
  • Light Frames: 32, 5-min. exposures
  • Calibration: 36 darks, 100 biases, 30 flats
  • Exposure Time: 160 min. (32 x 5 min.)
  • ISO: 800
  • Pre-Processing: PixInsight
  • Processing: Photoshop CC
  • Imaging Location: Los Angeles, Calif.

The Lagoon Nebula is one of the finest examples of a stellar nursery and one of only two nebulae visible to the naked eye. Located in Sagittarius, the nebula lies along the intersection between the galactic plane and the plane of our solar system (ecliptic plane), just a few degrees off a direct line of sight to our galactic center (Sgr A*).

The Lagoon is a giant cloud of dust and gas about 100 ly wide, 50 ly high, and about 4,100 ly away. Peppered throughout its expanse are a number of smaller dark features called Bok globules, which astronomers believe to be stars in the making. These “protostars” consist of dense, light-absorbing balls of gas and dust collapsing under their own weight, a process that also created the open cluster of new stars (NGC 6530) that now makes the whole nebula glow. These new stars are only a few million years old, infants on a cosmological time scale.

Ultraviolet light from NGC 6530 and other stars within the nebula causes the hydrogen gas to glow (fluoresce) in the red. A special narrowband filter placed over the camera sensor lets only this red light through and blocks everything else, which allows emission nebulae like the Lagoon to be photographed from light-polluted cities like Los Angeles.

[For Brian — friend, physicist, outdoorsman. You are greatly missed.]

Star-Spangled Eagle

Star-Spangled Eagle

The Eagle Nebula spreads its wings among a kaleidoscope of glittering stars.

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  • Telescope: Stellarvue SVA130T-IS
  • Mount: Losmandy G-11 with Gemini 2 controller
  • Autoguiding: Yes
  • Optical Configuration: 1x 910 mm (f/7)
  • Camera: Canon 60Da
  • Light Frames: 24, 300-s subframes stacked (120 min.)
  • Calibration: None (no darks, no flats, no biases)
  • Exposure Time(s): 2 h or 120 min. (24 x 5 min.)
  • ISO: 800
  • Pre-processing & Processing: PixInsight
  • Post-Processing: Photoshop CC
  • Imaging Location: Sierra Nevada Mountains (Altitude: 8,600 ft)

When photographing the cosmos, the path to accurate color reproduction often lies in the stars. This image of the Eagle Nebula reveals a broad range of star colors calibrated from their true color temperatures. Faithful depiction of star color ensures the color fidelity of other objects in the image, too.

The deep red color of the Eagle Nebula originates from light emitted by singly ionized hydrogen gas (H-alpha). The vast clouds of gas and dust in nebulae make them effective stellar nurseries, where the stuff of the universe is transformed into gleaming new stars.

The Eagle, Take Two

The Eagle Nebula
Reprocessed image of the Eagle Nebula achieves better color rendition and higher detail.

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  • Telescope: Stellarvue SVA130T-IS
  • Mount: Losmandy G-11 with Gemini 2 controller
  • Autoguiding: Yes
  • Optical Configuration: 1x 910 mm (f/7)
  • Camera: Canon 60Da
  • Light Frames: 24, 300-s subframes stacked (120 min.)
  • Calibration: None (no darks, no flats, no biases)
  • Exposure Time(s): 2 h or 120 min. (24 x 5 min.)
  • ISO: 800
  • Pre-processing & Processing: PixInsight
  • Post-Processing: Photoshop CC
  • Imaging Location: Sierra Nevada Mountains (Altitude: 8,600 ft)

Reprocessing image data of the Eagle Nebula (M16) that was shot last year has yielded better detail and higher color accuracy.

Home to the famous “Pillars of Creation,” the Eagle Nebula in the constellation Serpens is a diffuse emission nebula about 7,000 light-years from us. The small dark region of gas and dust near the center of the nebula resembles the silhouette of an eagle, hence the name. This small area of the nebula also defines the so-called Pillars of Creation made famous by a composite high-resolution image taken with the Hubble Space Telescope.

https://www.nasa.gov/content/goddard/hubble-goes-high-definition-to-revisit-iconic-pillars-of-creation

The deep red color of the Eagle Nebula originates from light emitted by singly ionized hydrogen gas (H-alpha). The vast clouds of gas and dust in nebulae make them effective stellar nurseries, where the stuff of the universe is transformed into gleaming new stars.

The Horsehead Nebula…from L.A.

The Horsehead Nebula

The Horsehead Nebula and Flame Nebula shot with a DSLR from L.A. in H-alpha light

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  • Telescope: Stellarvue SVA130T-IS
  • Mount: Losmandy G-11 with Gemini 2 controller
  • Autoguiding: Yes
  • Optical Configuration: 0.72x field flattener & reducer (f/5)
  • Filter: 12-nm narrowband H-alpha
  • Camera: Canon 60Da
  • Light Frames: 12, 4-min. exposures
  • Calibration: 13 darks, 100 biases, 30 flats
  • Exposure Time: 48 min. (12 x 4 min.)
  • ISO: 1600
  • Pre-Processing: PixInsight
  • Processing: Photoshop CC (processed in a single red channel and flattened)
  • Imaging Location: Los Angeles, Calif.

Photographing wispy deep-sky objects (DSOs) in the light-polluted skies of Los Angeles is not for the faint of heart. L.A. was an early adopter of LED streetlights; so night has now become day, ablaze with broadband sky glow. But those gossamer DSOs can be photographed under such conditions, as the image above of the Horsehead Nebula and Flame Nebula proves. The trick is to use a narrowband filter in front of the camera sensor, which blocks all wavelengths of light except the ones of interest. In this case, the wavelength of interest is the red emission line of hydrogen-alpha at 656 nm…aka, H-alpha. The Horsehead and Flame nebulae both emit at the H-alpha wavelength, so the filter allows their “voices” to be “heard” above the raucous roar of urban light pollution.

This image makes use of a narrowband H-alpha filter with a full-width half-max transmission window of 12 nm. It is a proof-of-concept shot intended to flush out the process and nail down some of the parameters (see bulleted details above). Wind and the meridian precluded taking more light frames, which would have further enhanced the quality and detail of the image. During the imaging session, a very bright LED streetlight gleamed at full intensity about 50 yards away, and the full moon (two days past full) was rising in the east. Yet, the results speak for themselves. It can be done, and done well.

Stay tuned for more narrowband images to come on this website.

Nighttime Lights of L.A.

The city lights of L.A. transform night into day.