August 2011 – The Amazing Sky

August 24, 2011August 24, 2011

Bow Lake by Moonlight (The Movie)

Here is the time-lapse movie I took last Saturday night, August 20, on a perfect night at Bow Lake in Banff, Alberta.

The sequence starts in bright twilight then darkens to full night with the Milky Way over the mountain silhouettes. The peaks then light up as they catch the light of the rising last quarter Moon coming up about 11:30 pm in the east. The moonlight creeps down the mountains to light up the entire valley and the lake. The sky brightens to deep blue again. The sequence ends about 3:30 am.

There was hardly a cloud in the sky all night, unusual for locations near the large icefields that straddle the continental divide.

I assembled the movie from 454 frames, each 40 seconds in exposure time, and taken 1 second apart.

August 22, 2011

Bow Lake By Moonlight

This was a truly magical scene — the Milky Way over Bow Glacier, and mountains lit by moonlight and reflected in the waters of Bow Lake.

Last Saturday night, August 20, 2011, brought some of the clearest skies I’ve seen in the Rockies. To take advantage of them, I headed to Bow Lake, in Banff, a favourite and very photogenic location for day and nighttime shooting. I hadn’t been there at night since the film days, pre-2004.

This shot is one of 450 frames taken as part of a time-lapse sequence, showing the Milky Way moving over Bow Lake. Here, at about 2 a.m. the light from the rising last quarter Moon is illuminating the peaks, and the Milky Way is perfectly placed over the end of Bow Lake and Bow Glacier, source of the waters of the Bow River and what Calgarians drink!

The sky is blue from moonlight. Last quarter moons are wonderful for nightscapes — providing enough light to illuminate the landscape but not so much as to wash out the sky and Milky Way. But making use of that phase of the Moon means very late nights of shooting. I packed it in this night at 4 a.m.

August 20, 2011

Space Station Over the Rockies

This was the view Friday night, August 19, 2011, as the International Space Station flew over Banff, Alberta and the Canadian Rockies.

I took this shot (actually this is a composite of three successive exposures) from the viewpoint on Mt. Norquay overlooking the Banff townsite and the Trans-Canada Highway interchange, unfortunately all too well lit. This might well be a case study in light pollution as well.

But the lights in the valley don’t diminish the Milky Way above, and the sky-wide streak created by the passage from west to east of the Space Station. What looks like a brilliant star to the eye turns into a streak here due to the three 45-second time exposures I used to capture this scene. The lens is the 8mm fish-eye, and these frames are from a 400-frame time-lapse movie for the planetarium dome.

August 16, 2011August 16, 2011

Lake Louise by Moonlight — The Movie

Here is the time-lapse movie I took last Saturday night at Lake Louise, Alberta, under the light of the Full Moon. My previous blog featured a still frame from the beginning of this sequence.

The night starts clear, but as often happens, clouds move in, blowing off the cold icefields of the continental divide. It does make for a nice effect in time-lapse, one of few instances in astronomy where some clouds can be useful!

Also notice how the reflection disappears as the lake breaks up into waves briefly, as wind blows in now and then through the night. The Full Moon is rising behind the camera, causing the lake to light up as moonlight illuminates more of the lake’s surface. Shadows move across the mountainsides. Arcturus is the bright star setting at right. The red object at left is a moored canoe, moving about on the lake.

I took this movie over 4 hours from 10:30 pm to 2:30 am, taking 477 frames with the Canon 7D and 10mm lens. For time-lapse movies like this, I process the full-size RAW files in Adobe Camera Raw and Bridge, then use Photoshop’s Image Processor to export them all to smaller size JPGs. From that set, I use Photoshop CS5 Extended’s “Motion” feature to assemble the folder of JPGs into a movie, in this case at 24 frames per second, a little fast perhaps for this sequence, but it’s easy to change if needed. Photoshop then renders that image file out as a Quicktime movie. What you see here is a tiny version of the final HD-sized video.

August 14, 2011

Lake Louise by Moonlight

This has to be one of the most photogenic and photographed places in the world. Here it is in a different light, moonlight.

This is Lake Louise, in Banff National Park, Alberta. A few hours before I took this photo on Saturday, August 13, where I stood would have been swarming with thousands of people. But at midnight there was no one about. I had the view to myself.

This looks like a daytime shot, except the stars give it away. Instead, it is the Full Moon, behind the camera, providing the illumination. Contrary to Hollywood lighting clichés, moonlight is not blue. It is the same colour as sunlight, because it is sunlight, just much fainter, reflected off the Moon’s neutral grey surface.

In this view we are looking southwest, toward the stars of the summer sky setting behind the peaks of the continental divide. Arcturus is the bright star at right.

A calm night provided the glassy lake to reflect Mount Victoria and Victoria Glacier.

This is one frame of 477 30-second exposures I took over 4 hours, of the stars turning and eventually clouds blowing in across the sky from the icefields over the divide. It’s rare to get such a perfectly clear night in the Rockies. It was a wonderful to be there, and apparently to be the only one there, to experience it.

August 10, 2011August 10, 2011

Sunset in the City — This is Only a Test!

This is one for the time-lapse geeks!

One of the trickiest subjects for a time-lapse sequence is a smooth and seamless day-to-night transition. Exposure times vary from fractions of a second before sunset to several seconds at night fall.

How to do it? Manually shifting exposures is too much work and prone to error. Putting the camera on Automatic can work but inevitably results in an effect known in the time-lapse world as “flickering.” The camera’s automatically-judged exposures aren’t consistent from frame to frame so the final movie shows minor bright/dark flickering, making it look jerky.

For this test sequence of sunset over the Calgary skyline, I tried a new toy for the first time, as a solution.

The device is called the Little Bramper (for Bulb Ramping). It is a custom-made intervalometer that fires the camera shutter every few seconds (at whatever interval you desire). Nothing new there. But what’s unique is that it can be set to slowly increment the exposure time by as little as 1/1000th of a second from frame to frame, gradually increasing the exposure (“ramping” it) to accommodate the darkening scene. The result is a smooth transition from day to night with no flickering.

This was my first use of the Bramper and it wasn’t without its glitches. The shortest exposure the Bramper can provide (it always controls the camera thru its Bulb setting) is about 1/10th of a second (I had no idea camera shutters can fire as quickly as that even on Bulb).

But at the beginning of a sequence like this, with a bright sky, achieving that exposure (still quite long) means using a small f-stop, a slow ISO speed, or a neutral density filter, or all of the above. But as the sky darkens and exposures lengthen, exposures would become too long to fit within the desired interval between frames (typically no more than 5 to 10 seconds for a smooth sequence). So, to shorten the exposures you then have to open up the lens, switch to a faster ISO, or remove the ND filter, while also commanding the Bramper to quickly reduce its exposure time, all in one exposure cycle (i.e. 5 to 10 seconds) so as not to lose or ruin frames. Takes some coordination and practice (hit the Bramper’s button, adjust the camera, all within 5 seconds), and I didn’t get it right the first couple of times.

But overall, for a first test, the sequence turned out very well. The $80 Little Bramper does the job, though it does take careful monitoring through the sequence, not just to perform the exposure swaps, but to also watch that the ramping rate (adjustable on the fly) matches what the scene is doing and you aren’t under- or over-exposing. It’ll take a little more practice, but the results certainly are worth it.

It’s another neat tool in the time-lapse arsenal.

August 9, 2011

Milky Way in the Mountains

It’s rare to get such a clear night in the mountains but I used the opportunity last Thursday night to shoot the Milky Way in a twilight scene in Banff National Park.

I took this a little later on the same night as the previous blog’s image of the setting Moon. The location is the Vermilion Lakes, a familiar scenic spot for classic views of Banff and Mount Rundle reflected in the water, at far left. It is one of the few places in the mountains where you can look south over a low mountain skyline (to see the southern Milky Way) and over still water (to get reflections).

For this shot I used a fish-eye lens to record most of the sky and the summer Milky Way arching over the water. The sky was dark enough to show the Milky Way but still had a lingering blue tint from the last glow of deep twilight. The yellow glow at left to the east is from the urban lights of Banff.

The still image is one frame of 220 shot over 4 hours for a time-lapse video, for projection in a full-dome video-equipped planetarium. Just so happens we’re building one in Calgary to open in early 2012.

August 7, 2011August 7, 2011

Moon in the Mountains

I’ve been chasing the Moon this week. I caught up with it last Thursday night, August 4, in Banff, with the waxing crescent Moon low in the southwest at dusk.

The location is the upper Vermilion Lake just outside the Banff townsite. The golden reflection of the low Moon on the water, the slope of the mountainside and its reflection, the dock and steps, and the tail lights from a vehicle on Highway 1 just up the hill (I decided to leave them in!) make for what I think is an interesting composition of converging lines.

I got set up and in position just in time to catch the scene at the magic hour of twilight, when the sky is dark enough the show deep colours and the Moon’s entire disk shows up, but before the sky gets too dark and the Moon too bright to make an interesting scene.

Even so, the contrast in such a scene is still very high. So to capture it more as your eye would have seen it I used a stack of five exposures, taken in rapid succession, each 2/3rds of an f-stop apart. I then merged the frames with Photoshop’s High Dynamic Range routine to create a scene that brings out detail in the foreground without overexposing the Moon and sky.

A technical method to capture a simple scene of serenity in the mountains.

August 7, 2011August 7, 2011

Moonscape

As all the other sunset photographers were packing up for the night, I was just getting started. This is the scene last night, with the waxing Moon hanging over the moonscape of Dinosaur Provincial Park in southern Alberta.

I took this in deep twilight, when the sky is tinted with subtle colours complementing the earth tones of the landscape below.

Dinosaur Park is the world’s best repository of late Cretaceous fossils, being unearthed as the terrain made of ancient volcanic ash erodes away with every rainstorm. Though the formations date from the Cretaceous some 70 million years ago when this area of Alberta was a bayou-like swamp, the badlands landscape we see today was created at the end of the last ice age when glacial floods poured over the landscape, carving the channels occupied by rivers today, like the Red Deer River that flows through Dinosaur Park.

It’s a favourite spot of mine, just an hour east of where I live, to shoot sunsets and moonrises, and twilight landscapes like this one.

August 6, 2011August 11, 2011

Auroral All-Sky Dance

Here is nearly two hours of auroral dancing compressed into 25 seconds.

This was the “all-sky” aurora of August 5/6, 2011, widely seen over North America but perhaps (from early reports) best from the western half, especially Canada, favoured for Northern Lights due to our latitude.

I shot this with the 8mm fish-eye lens and the Canon 5D MkII. The movie consists of 255 frames, each 24 to 30 seconds in exposure duration, taken one second apart. ISO speed was 1600 and aperture f/3.5. The playback frame rate is 10 fps.

This display was quite chaotic, without the graceful rippling curtains present in many displays, but rather huge patches of sky turning off and on. This is typical of an aurora in the declining part of the storm — it had already been raging for several hours by the time it got dark here in Alberta.

Nor was the display very bright, so the longer exposures needed to record it well further blur any fine motion. Nevertheless, you get a good idea of the intense activity this aurora displayed. The magnetosphere was jumping last night!

August 6, 2011

Auroras At Last!

It’s been quite a while since I’ve seen a display of Northern Lights as good as this one. But with the Sun picking up in activity from a record lull in the last few years, great all-sky displays like this might become more frequent.

The last time I saw aurora cover most of the sky like it did last night (August 5) was back in the days of shooting film. So this was the first chance I had to shoot an all-sky aurora with digital cameras. This is with the Canon 7D and the ultra-wide 10-22mm zoom. I also shot with the fish-eye 8mm, and an “all-sky” movie of those frames will be in the next posting.

This display was widely seen and predicted, as solar monitoring satellites had observed major flares on the Sun earlier in the week and tracked the resulting “coronal mass ejections” across the solar system. We knew they were aimed at Earth and would hit August 5. In this case, the resulting geomagnetic storm raged for long enough that people across a wide swath of longitudes from Europe to North America were able to see the display during their local night, August 5/6. Even people in the northern U.S. had a good look.

While the display was certainly active and extensive it never did get really bright. So this one still falls short of the “10 out 10” scale for spectacle. Nevertheless, as digital cameras can do so well, the images picked up the greens from glowing oxygen with remarkable intensity. More interesting are the purples, seen toward the beginning of the night but then they faded away. The purple tints come from the tops of the towering curtains of aurora which often glow red from nitrogen molecules at very high altitudes being charged up and excited. But the tops of the curtains can also be lit by sunlight. The blue from the sunlight and the red from the aurora itself mix to produce a purple tint. Only the camera picked this up.

August 2, 2011

The Comet and the Cluster

This was the scene Monday night and into Tuesday morning, August 1/2, as a relatively new comet to our skies passed a bright globular cluster known as M15 in Pegasus. The comet is Comet Garradd, or more formally C/2009 P1. Here it glows with the characteristic cyan tint of many comets and sports a stubby fan-shaped tail.

As comets move across the sky they often appear near prominent deep-sky objects for a night or two before moving on. Comet Garradd has a number of such encounters coming up: with the globular cluster M71 on August 26, and then near the neat Coathanger cluster September 1 through 3.

Comet Garradd can be spotted now from a dark site in big astronomy binoculars and is a fine sight in a telescope. However, it is well below the threshold of naked-eye brightness and is expected to remain so as it moves high across the summer sky from east to west and then into the western evening sky in late autumn. It is certainly well-placed for viewing, but only comet aficionados are likely to pay much attention to it. Plus astrophotographers taking advantage of photo ops like this one.

August 1, 2011

The Glowing Heart of Cygnus

Look straight up on a summer night in the northern hemisphere and you are looking into this region of sky. This is the centre — the heart — of Cygnus the swan, marked here by the bright star called Sadr, or Gamma Cygni.

While the star is easily visible to the unaided eye, the glowing clouds of gas surrounding it are not. Only long exposure images reveal the amazing swirls of nebulosity in the middle of Cygnus.

The main cloud at left, split by a dark lane of dust, is catalogued as IC 1318. The little crescent-shaped nebula at right is NGC 6888, or more appropriately, the Crescent Nebula. It formed when a hot giant star blew off its outer layers, to add to the general melee of hydrogen and other elements. But note the little blue reflection nebulas at top left. Oddly out of place!

New stars are forming in this region, located about 1500 light years away down the Cygnus arm that we live in, in the Milky Way Galaxy.

This field can be framed nicely by binoculars or a low-power telescope, but only the brightest bits of this nebulosity will show up in the eyepiece as grey ghosts, and then only with the aid of a specialized nebula filter.

I took this shot on Saturday night, July 30, 2011 with the Borg 77mm f/4 astrograph lens and Canon 5D MkII camera. Other stats are similar to the previous blog post. It’s certainly my best shot of this area of sky.