Wednesday, July 20, 2016

Milky Way Over Rockfish Valley

Rockfish Valley Overlook, Blue Ridge Parkway, Virginia. July 9th, 2016. Ten panel mosaic, 40 second exposures at ISO3200, Canon 550D, Rokinon 16mm f/2.0 lens at f2.4, Vixen Polarie Sky Tracker at 1/2 sidereal rate. High resolution version here:

After a month of persistent cloud cover, the Clear Sky Clock announced a mostly clear night in western Virginia on a Saturday. Perfect, I thought. For a while I have wanted to capture the Milky Way from Rockfish Gap Overlook on Interstate 64 near the Blue Ridge Parkway, so I packed up my wide-field imaging gear and drove west, well before sunset.

High-level cirrus permeated the evening sky as I left town along with some large cumulus floating about that I reassured myself would clear out by the time I made it 2.5 hours away to the mountains. But mile after mile, the amber glow of the sun reflecting off those clouds lit up the sky like an orange peel and looking far to the west showed nothing but red and grey clouds, destined to obscure the night sky. I began to feel more and more foolish with each passing minute, knowing that if I arrive to mountains veiled in cloud cover, I would have to turn around and drive 2.5 hours back home with my tail between my legs - five hours wasted for nothing! Suddenly, I remembered a quote that my father would often say to me. I could hear his voice clearly,

“Far better is it to dare mighty things, to win glorious triumphs, even though checkered by failure... than to rank with those poor spirits who neither enjoy nor suffer much, because they live in a gray twilight that knows not victory nor defeat.” - Theodore Roosevelt

He was right. It is too easy to give up and never know what the mountains would give me that night. Great things are accomplished by hard work, lost sleep and sacrifice, never by laying on the couch and not even trying. Besides, anyone that has ever accomplished anything great from the couch is an asshole.

Re-invigorated, I pressed onward and arrived at Rockfish Gap around 10 p.m. Astronomical twilight had not yet ended so I decided to explore south along the Blue Ridge Parkway to kill some time. Within a mile, I stumbled upon Rockfish Valley Overlook, pictured above. Now this was the view I was looking for! A wide-open vista with the Milky Way arched over the hazy-blue valley, diving into a mountain range to the south. The stars twinkled above the shimmering lights of the town below while Mars and Saturn shone boldly among the stars of Scorpio.

I quickly sat up my gear and got to work, all the while having a pleasant conversation with a local who was also taking in the view. I soon realized that this was a popular overlook. Car headlights blasted the area every minute or so, some cars careening into the turn-off to peer into the valley. This was a real challenge because the headlights caused the foreground to overexpose and I would have to start over again.

I took over a dozen overlapping exposures, hoping to capture the breadth of the overlook in a multi-frame mosaic. Later I learned that I missed some landscape and sky on either side and that I couldn’t crop the part that I did capture in a satisfactory way, so I left the mosaic uncropped. With a little better planning, I may try this shot again, probably in the morning when there is less traffic.

What I really like about Rockfish Valley Overlook is how peaceful the town lights look below the glow of stars above. They almost look like lights from a model railroad town, quiet and serene. I’m not sure how well I captured that in my photo. I think the juxtaposition of the frail Milky Way against the bold, yellow city lights illuminating the clouds along the horizon is the stronger story. Who is winning here? Man or cosmos? We have built a world of concrete, steel and lights - a testament to the dominance of humankind over the natural world, when in reality we are temporary tenants of a stone hurling around an ordinary star in an unimaginably large space. Our sense of self-importance needs tamed from time to time.

I packed up around midnight, thinking about the comforts of beer and couch some 2.5 hours away. As I drove towards the interstate I realized that I have traveled this far from home, so why call it a night now? There is still plenty of darkness and adventure to behold! With that, I turned toward Shenandoah National Park in search of more starry wonders. I’ll continue the story in my next blog post.

Technical notes:
This image is a composite of ten 40 second exposures in landscape orientation on a Vixen Polarie Sky Tracker at ½ sidereal rate, ISO3200, f/2.4, custom white balance. I learned that I cannot turn the camera into portrait orientation when facing south because on the camera bumps into the Polarie body. Facing north, this is not an issue.

For post-processing, I gave Adobe Photoshop and Lightroom a shot and I must admit that I really like this software for landscape astrophotography. Lightroom Photo Merge stitched all ten panels together seamlessly. I used PixInsight for noise reduction and then processed the rest using adjustment layers in Photoshop with a soft hand.

Processing Workflow
(LR) Lightroom, (PS) Photoshop CC, (PI) Pixinsight
1. Correct lens distortion, chromatic aberration, exposure -1, blacks +25, tone curve to boost darkest values, export individual panels as sRGB 16-bit .tiffs (LR)
2. Stitch panels into panorama, export as sRGB 16-bit tiff with transparency (LR, Photo Merge, spherical projection)
3. Noise reduction (PI, TVGDenoise to lightness, strength 5, edge protection 2E-4, iterations 200; w/extracted lightness mask as local support and inverted lightness mask to target darker areas).
4. Correct light pollution by selecting previews at various parts of the sky away from the Milky Way and adjusting the red and green curves until the RGB histograms overlap (PS, Curves with mask protecting the foreground with transparency 60%).
5. Increase sky contrast with strong “S” curve (PS Curves with mask selecting the sky).
6. Accentuate contrast between Milky Way dust lanes and brighter regions (PS, Curves with mask selecting sky).
7. Lower sky background brightness slightly (PS, Curves with mask selecting sky).
8. Increase overall brightness (PS, Exposure +0.9).
9. Increase sky contrast (Brightness/Contrast adjustment, PS, Contrast +18)
10. Adjust contrast and brightness of foreground to soften transition to sky (PS Curves with mask selecting foreground).
11. Darken sky slightly (PS, Curves with mask selecting sky).
12. Add dark color around borders (PS, Paint Bucket, RGB = 12, 12, 12).

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