For the second time, I was lucky enough to see the aurora from Perth, last night. It was quite an impressive display; by the time I got out to darker skies it was quite low above the horizon, but the greens were strong to the naked eye and some strong rays came and went over time.
I still need to work on a good viewing location, but out beyond Rhynd is a good start.
A classic location for long-exposure night-time photography: standing on the bridge over the M90 at Rhynd, with the road snaking away into the distance… and a clear display of noctilucent clouds above Kinnoull Hill.
From wikipedia:
Night clouds or noctilucent clouds are tenuous cloud-like phenomena that are the “ragged edge” of a much brighter and pervasive polar cloud layer called polar mesospheric clouds in the upper atmosphere, visible in a deep twilight. They are made of crystals of water ice. Noctilucent roughly means night shining in Latin. They are most commonly observed in the summer months at latitudes between 50° and 70° north and south of the equator. They can be observed only when the Sun is below the horizon.
They are the highest clouds in Earth’s atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometres (47 to 53 mi). They are normally too faint to be seen, and are visible only when illuminated by sunlight from below the horizon while the lower layers of the atmosphere are in the Earth’s shadow. Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon; there is no record of their observation before 1885.
A handful of photos taken after dark from the Queen’s Bridge in town, waiting for the fireworks to happen.
A fairly obvious shot from a viewing location on the south side of the Tay, the road bridge disappearing in a stream of lights flowing to Dundee in the fog. At night. As a long exposure, because it’s what one does, right?
There’s something a bit romantic about the cosiness of suburban streets in the fog.
Perth on a foggy night
Don’t ask me why Perth council thought to have a winter festival in the middle of November, when it’s not Christmas, it’s not Advent and it’s not even Winter yet… but the fireworks were well pretty!
Noctilucent (“night-shining”) clouds are a rare phenomenon: the highest clouds in the atmosphere, at altitudes between 47-53 miles, consisting of tiny crystals of water ice about 100nm in diameter and requiring very cold temperatures to form. Not fully understood, they are a recently discovered meterological phenomenon with no record of their observation before 1885.
They also make a beautiful display of pale bright fibrous blue against the cobalt velvet of night…
Two views, part of a stitched panorama.
I did only say this blog would be mostly mobile photography. Time for something a little different.
Thanks to a tip-off from a Facebook page and some friends in Leeds, a couple of nights ago I watched the International Space Station passing overhead for the first time. I didn’t know what to expect; the magnitude (-3.0) hinted at it being “incredibly bright”, and indeed so it was. Bearing in mind I had no idea what to expect, the less said about those attempts at photographing it, the better.
But last night, I investigated further using Heavens Above and saw another passing was scheduled for 2329hrs. Seeing the weather conditions were favourable, I chose a location toward the top of a nearby hill and stood around to wait.
Approaching from the west:
disappearing toward the east:
Some notes on the image processing:
The approach image comes from 6 frames at ISO800, f/4, 14mm, 15s each, taken in quick successsion; the departure image used 12 frames at ISO800, f/5, 29mm, 30s each. The high ISO was chosen partly in order to give me a chance to compose and track, partly to ensure the ISS showed up bright against the background. Both apertures are fairly wide to maximize the light captured yet give a reasonable depth of field in the landscape given the wide-angle focal lengths in use (I had pre-focussed the camera on infinity half an hour before setting out). High-ISO sensor noise is thermal and therefore random; however, long-exposure sensor noise gives a fixed pattern of hot and dead pixels. Therefore, by keeping the exposures short at 15-30s I was able to pan between shots, aiding the composition (the ISS’ path is subject to slight changes at the last minute), meaning all pixels could be calculated from more than one image with spatial offsets – stacking reduces image-noise. Finally, I took a dark frame (with the lens-cap on) to record the actual noise profile.
Initial RAW conversion used RawTherapee in order to subtract the dark-frame; images were stitched together using Hugin and enfuse biassed toward image entropy for high quality landscape and sky tones; because the averaging process reduced the intensity of the ISS’s track, I further blended the intermediate aligned images using ImageMagick and the maximum operator and overlaid the results selectively using the GIMP. Final colour toning and spatial control (high- and low-pass filters) was done in Darktable.
Update 2013-06-18: the approach photo is now available for prints or download at 500px.