Monday, September 1, 2014

How to photograph the aurora: Part 2

I just saw this page shared with a beginner to help them photograph the aurora. It's typical of the advice given to amateurs, and (in my opinion) typically bad and/or irrelevant. Here's why:

Location is a key factor when preparing to photograph the northern lights. A clear shot of northern and eastern skies is helpful.

Right from the start they're advising you to do something boring. If you go somewhere that's clear and empty all the way to the north so you just see the aurora above a distant horizon, your picture will be boring.

As activity increases it normally starts from the east as Earth rotates into the aurora.

...No. The auroral surges come from the east pre-midnight because that's the direction from which the magnetic field lines are convecting. Post-midnight the auroral surges come from the west. Earth's rotation had nothing to do with this.

there are lots of other [places to photograph the aurora], just look for cars parked along the roads

And you will spend your whole night fighting the headlights and flashlights of all those people you stopped next to. And for what? The aurora looks the same a mile down the road as it does right there.

How about a tripod? If you've got one, dust it off and figure out its use before you're out in the cold, where the plastic becomes brittle and has a tendency to break in extreme temperatures.

Don't get a plastic tripod. They wobble. The whole point of a tripod is not to wobble.

Camera batteries in the cold lose power real quick ... At 40 below zero, a camera battery lasts around 20 minutes.

*Shrug* I've never needed to swap my batteries during a shoot. If I'm going to leave the camera running hands-off for a while I pull a neck gaiter over the camera, with the lens poking out one end, to keep the wind off, and my standard battery will last a couple hours at 40 below. I don't suppose it's bad advice, but it's not that big of a worry.

Keep a Ziploc bag handy for storing your camera

Take the memory card out of the camera before you go back inside, put the camera in some kind of a bag you can close, and don't open it till morning. Your backpack or regular camera bag is fine; it doesn't need to be waterproof. If you forget to take the memory card out before you go inside, just open the bag, take it out, and reclose it. Your camera will be fine.

Make sure your in-camera storage media card is clear of any other photos. Long exposures require a lot of room.

I... what? It takes the same amount of memory to store a pixel of the same value, regardless of how long it took to capture that pixel. I find aurora photos often require less storage room than daylight photos.

Lens filters can also produce what's known as a ghosting reflection between filter and front glass of the lens.

Not unless you're looking at something really bright and localized, like a street light or the moon. The aurora will not do this. The filter will, however, work as an interferometer and leave diffraction rings in your photo. This happens anytime you use the filter, but it's only noticeable when looking at a monochromatic light source like the aurora. So yeah, take your filters off... that's just not the reason why.

Rotating a lens's manual focus clockwise will set it to infinity. A good rule of thumb is to rotate the lens to infinity and then back it off just a hair. 

Which direction you rotate the lens to focus to infinity is absolutely dependent on the lens. Nikon brand lenses usually go the opposite direction of Canon brand lenses, and I use lenses on my camera that go both ways. And regardless, this is not how you should set your focus. Find the brightest far away point source, which will be the Moon if it's up, a distant street light if one's visible, or the brightest star otherwise. Point at it, switch to live view, zoom all the way in (digital/live view screen zoom, not lens zoom), and focus. You can use the chromatic aberration to set the focus: When you pass through focus the fringes change from purple to green.

Set your lens aperture to the lowest number.

Probably, but maybe not. Fast lenses usually have a lot of aberration when used wide open, and it's a lot more visible on point sources like stars than it is in daylight pictures. You're going to have to decide for yourself where you want to set the compromise between speed and sharpness. I usually shoot my f/1.8 lenses at f/2, and if the aurora is bright enough to get away with it I'll go to f/2.8.

Some cameras also have a long exposure noise reduction function. If yours has it, turn it on.

I would never use this. The camera takes a dark frame after each exposure and subtracts it from the light image. You can do this yourself in Photoshop or whatever, without wasting the time to take a new dark frame every single exposure. The aurora isn't going to wait for that.

On DSL cameras, mirror opening and closing creates most vibrations in long exposures. There are other options, though. Most cameras are equipped with a self-timer. Set it to a short time and push the shutter release to minimize camera movement. If "mirror lock up" is an option, use it.

If mirror slap is seriously causing vibrations in your aurora photos, your tripod is so worthless you might as well be balancing the camera on a rock. This is a consideration for long focal length astrophotography, not wide angle aurora work.

If the preview shows up black, do not, repeat, DO NOT, delete. Your camera will capture more than meets the eye. Due to long exposures, cameras record a lot more than the eye can process, and more than likely you won't be able to see it on the camera screen.

This is all kinds of What. A long exposure is not going to be black on your preview screen by virtue of the fact that it's a long exposure: The value of each pixel is integrated over the exposure, and the preview shows the final image, which is the total light in that pixel. If it's black on your preview screen, it's not going to get any less black on your computer. If it's merely dark on the preview, you may be okay depending on how noisy it is. And you should look at the histogram and not rely totally on the preview image: The preview image is a processed .jpg, if you're shooting RAW (and you should be) the histogram is a better idea of what you have and haven't captured. The RAW file will hold low-level stuff that doesn't show up on the preview, but this is because the preview can only show 8 bits while the RAW captures 12 or 14; it has nothing to do with the fact that it's a long exposure.

Once you've found a good exposure setting, avoid looking at the preview.

So how do you know when you need to change the exposure?

Don't breathe on or around the camera.

Okay, I will stop breathing. :/ Just direct your breath away from the optics, okay?

Friday, August 8, 2014

Sprites 2014

Sprites and airglow over Laramie

The Sprites 2014 campaign has concluded, and we mostly got burned by the weather. This year, instead of doing an aerial campaign, we set up at Wyoming Infrared Observatory on top of Jelm Mountain, WY. The first night was very good; for a while we were seeing about a sprite per minute. I got around 30 new dSLR images of sprites during that time frame, but since they were visible above the Laramie light pollution most of them were too faint to be very interesting. The best was the one above, and this one with the Andromeda Galaxy on the left was nice:

Sprites, airglow, Andromeda Galaxy

But after that first night, the weather never really cooperated again to give us a good amount of sprites in a clear part of sky. The sky at 10,000 feet and Bortle class 1 was very nice so I took a few pictures of just the Milky Way and airglow:

Milky Way, airglow, and storm over Fort Collins, CO

Milky Way from Wyoming Infrared Observatory

And I spent a couple hours one night setting up to do wide field astrophotography (the best kind :P) of the constellation Cygnus with the North America Nebula which turned out pretty nice:

North America Nebula in the Cygnus constellation

I really need to figure out the cold weather issues with my clock drive so I can do these kind of shots from Alaska where the sky is dark and super stable due to the cold.

I also flew the drone around the observatory a few times, this one it was too windy so I immediately brought it back down to land:



Then a few days later it was calm enough to get a good flight:



And then the last morning there I tried one more flight on another calm wind morning, but for some reason my drone throttled up but wouldn't throttle down, so I watched it disappear into the sky and never saw it again :(

I've since been back on the White Salmon River in Washington, from Monday evening until now. I've been doing trip photography for All Adventures Rafting and made a little money, and I expect we'll see some of my photos on their website and Facebook page. Today I'm heading out to drive north back to Alaska. Later y'all.

Tuesday, July 15, 2014

Capitol Reef National Park

New Mexico

^ Road sign representative of northern New Mexico, which really has nothing to do with anything else in this post.

Capitol Reef, in south central Utah, is a severely underrated national park. The parks in southern Utah are some of the best in the country, and while places like Arches or Zion get all the publicity, Capitol Reef has top notch desert scenery without the crowds. A lot of the park is accessible via rough two-track trails, and I decided to drive Cathedral Valley road, which goes through (surprise) Cathedral Valley, including a couple of rock formations called Temple of the Sun and Temple of the Moon that I've wanted to visit and photograph for a couple of years but haven't had a vehicle I could confidently drive out there.

I mounted my GoPro to the roof of the car to film the drive down Cathedral Valley Road, using the GoPro suction cup mount. Like basically everything else GoPro branded, the mount sounds good in theory but doesn't actually work very well. The video was extremely shaky, and the entire mount would pop loose every few minutes. Eventually I gave up on the GoPro mount and stuck the camera on my GorillaPod on the hood, with one of the feet stuck under a wiper blade. This worked better, but I still wasn't satisfied with it. I think I'm going to rig up some better mounting system. A tripod ball head on the front of the roof rack should be good, and allows me to mount better cameras than the GoPro.

The western half of Cathedral Valley road had a steep, loose descent down to the valley floor which could be interesting for a 2WD vehicle on ascent. Then it was sandy road most of the way. After arriving at Temple of the Sun/Moon in late afternoon, I did a few pictures:

Capitol Reef backcountry

Capitol Reef backcountry

Then I got the drone out and did a flight right over Temple of the Moon:



I wanted to shoot the formations in good sunset light, and again after dark. So I pulled into the shade under Temple of the Moon and set up a timelapse while I waited. Then I laid out my sleeping pad and went for a four hour nap until sunset. I woke up an hour and a half later with grit in my teeth from the wind whipping everywhere. Seems a storm was brewing while I was asleep:



Now it was decision time: I could keep waiting for sunset, risking the rain. The problem with rain is the road crossed several muddy washes that could turn into flash floods pretty easily, then I'd be stuck waiting for the water to go back down. Since the clouds looked like they'd ruin my evening and nighttime shots anyway, I decided to get while the gettin' was good. The eastern half of the road went through some really neat badlands-style scenery with lots of switchbacks on slickrock around small canyons and mesas. Definitely the more interesting half of the road, and also less rough; a regular passenger car could do this in good weather. I stopped for a picture:

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And then it was back out to the highway. It took all afternoon to go 50 miles. I guess I'll have to come back another time since I didn't get to shoot the location the way I wanted.

Wednesday, July 9, 2014

North Carolina Outer Banks

Seashell

After my time in the Columbia River Gorge, I hopped a plane to the other side of the country to spend a week on the Outer Banks of North Carolina. This one was for business: I was supporting a rocket launch to test a new mechanism we'll use this fall in Svalbard. The rocket's purpose is to release a trail of luminous clouds in the high atmosphere, the clouds drift with the winds way up there, and we watch to learn about those high altitude winds. My job was to run some of the cameras that track the clouds. The rocket launches from NASA Wallops Flight Facility on Virginia's eastern shore, and a slew of cameras is deployed both there and down at the town of Duck on the NC Outer Banks. We need cameras at two locations to be able to pinpoint the clouds in 3 dimensions. I was in charge of the 'remote' site at Duck, which was on a concrete patio behind the building at a US Army Corps of Engineers site. I got my gear set up first thing:

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The larger tripod at the right is a very nice cinema tripod holding three scientific cameras; left to right, an Andor iXon EMCCD, a CCD video camera with an image intensifier, and an ATIK astronomical CCD. The computers on the table are necessary to run the EMCCD and ATIK, while the gear to run the ICCD is just inside the building on long cables. To the left are two Nikon D700s that a guy from Wallops was running, and I had a Nikon D610 running as well. We fielded so many cameras to get an idea of which worked best so we would know what to take to Svalbard.

After getting the setup worked out, my job was to be on station by 2:00am each morning and wait until our potential launch time around 4:30am. I usually arrived around 1:00am to be sure I was setup and ready to go well before necessary, and left around 5:30am. I slept until about 2:00pm then had the afternoon and evening to explore. The western side of the island is swampy:

Swamp mud

While the eastern side is beach:

Beach

Like everyone who's spent a lot of time in Alaska, I shrink like a vampire when exposed to bright direct sunlight. But after walking outside it only takes a few minutes to get used to it, and otherwise the weather was great (that would change the day after I left), varying from the 70s to the high 80s with a constant stiff breeze coming off the ocean. My favorite thing about the beach is the soundscape: The wind and waves give a good constant white noise, and the seabirds punctuate it well. I should get one of those 'sounds of the beach' tapes or something. I do feel like the beach is sort of a boring place to visit overall, at least the southeast and gulf coast beaches, where it's just a flat slope of sand into water. It seems like most of the interesting things you could do at the beach require too much gear and/or practice to be feasible for a visitor. If I lived here, I could definitely see myself taking advantage of the wind to take up kite boarding, and my whitewater kayak would probably be a lot of fun in the surf.

The first two nights we couldn't launch the rocket due to clouds and winds. The site I was working at has a private pier that sticks half a kilometer out into the water, which I spent a lot of time walking along. It's pretty dark out there, with no sounds but the wind and waves, which is kind of creepy (in a neat way) when you can't see anything and you're just walking through blackness listening to the sea. After your eyes have time to adjust to the dark, it's pretty nice:

Milky Way over Duck NC

Also, since the pier is private, people don't walk out there often, so seabirds have taken to roosting on the end. When I walked out there in the dark I scared them up, but since it was dark they couldn't see to fly anywhere so they just hovered on the wind all around me, not making any noise other than the flapping of their wings (which is rather loud on larger birds!). It was dark enough that I couldn't even tell if they were large gulls or pelicans, even though they were floating only a few feet away.

During the days I spent a lot of time in the Hatteras Island National Seashore just to the south, walking along the wild beaches and taking pictures in the afternoon light. Here's a couple from a 'focus on the blowing sand' afternoon:

Seashell and blowing sand

Blowing sand

And the Bodie Island lighthouse not long after sunset (it gets dark fast this far south!):

Bodie Island Lighthouse and Moon

The next two nights we had the weather conditions but couldn't launch because of commercial fishing boats in the impact area, which was annoying. One of those mornings after we shut down for the night I decided to walk out to the end of the pier and wait for sunrise:

Pier sunrise

Pier sunrise

While waiting, I started hearing a weird air venting noise. It sounded like a pipe that reached down to water level, and would blow air out the top when a wave passed in the bottom. So I started looking around and found that it was actually a pod of dolphins right under me, and the sound was their breathing.

The beaches, especially the less-traveled wild beaches, have a lot of ghost crabs scampering around. Ghost crabs are well camouflaged, fast, and skittish, so getting decent pictures isn't easy. Challenge accepted? I took a seat next to a few active crab holes and waited. As they got more used to me, they'd come out of their holes and stay put as long as I didn't move. I worked my way closer and closer like this, and eventually made it close enough to set my camera right outside their holes and lay in the sand behind it, tripping the shutter with a cable release. I started with my 150mm macro lens:

Ghost crab

But decided this could be better if I used a wider 50mm lens to get more of the environment in the shot:

Ghost crab

And I ended up pretty happy with this one taken just after sunset, with the crashing waves and pink sky behind:

Ghost crab sunset

I would have liked to try using a flash but I didn't bring one, and it probably would have scared the crabs too much anyway.

On early July 3, our last chance of the launch window, we finally got our opportunity to launch. Unfortunately, the rocket failed at the second stage and tumbled back to the ground like a giant flare. I think it only made it up to 27,000 feet. So we didn't even get to test the mechanism we wanted to test. Here's the video from Wallops of launch, which looks like something out of Kerbal Space Program:



Afterwards I packed all the gear up, finishing just after sunrise:

Sunrise on the pier

Aaand back to the other side of the country where I began my drive to Arkansas.