Star Party on Velebit

In mid August I was invited on a trip with a group of Croatian astrophotographers and astronomers to some remote, dark part of the country to watch/photograph stars. Since I love that challenging kind of photography, and chances for good night sky photo are minimal in the urban areas – I could not reject. The destination was small village of Sveti Rok in Lika, Croatia.

The basin of Lika is located behind the Velebit mountain, biggest (although not the highest) massif in Croatia. Velebit spans along the Adriatic coast in the length of 145 km (88 miles) from the town of Senj in the northwest, all the way to the river Zrmanja source and town of Knin in the southeast (hinterlands of town Zadar). Velebit stands as a barrier between coastal part of North Adriatic and the continental Croatia, causing two, geographically rather close areas, to have completely different climates. The part of Lika where we were heading (behind south part of Velebit), has no big cities or too many villages so the light pollution is very low and thus very good for the astrophotography which requires sky as dark as possible.

In the late afternoon, after some 2 hours of driving from Split, we arrived to the spot – a lonely and clear mountain glade, about 600 m above the sea level.

The conditions were perfect for the astrophotography; calm summer night was ahead of us, low humidity, rather low light pollution and no moonlight. Even though I don’t own a telescope, or a modified camera with cooled sensor – I could not wait to make some night sky photographs and to enjoy incredible view on the Milky way.

As we arrived on the location, the sun was already setting behind the peaks of Velebit, so there was no time to waste. Cars were full of equipment which needed to be assembled any fully functional by darkness.

I climbed up the small hill to get to know the surroundings. Some really nice sun rays formed when the Sun hid behind the mountain. It looked really cool.

Back on the ground, the preparation was in full swing; choosing a spot, unpacking, connecting cables, powering up, balancing the telescopes and rotating them to the right position, connecting to laptops, choosing which object to photograph that night, etc… So many operations to do before the shooting begins.

Watching this, one might conclude this has more to do with electronics and mechanics than photography. And that’s partly true but everything has it’s purpose and each detail is thoroughly prepared before.

This one looks like a real small field office. :)

Haha, when I see the next photo I’m thinking of how ridiculously fragile and small my Vanguard tripod looks like next to the astrophotography tripods. What’s otherwise perceived as quite sturdy and heavy tripod, now looks as though a touch of gentle breeze could blow it away in an instant :))

Oddly-looking devices began to grow all around the glade.

All the equipment doesn’t make sense if you don’t have a beer :))

Here’s the whole crew.

And the beer, of course.

Just one, we’ve hidden the rest. :)

I have put the tent up. Since I’ve brought it why not use it. It’s much more comfortable to sleep in a tent than in a car. Sleeping under the stars was not the option since by then I was already full of mosquito stings.

The night was slowly falling, and there were already many stars visible on the sky. Yet, for the astrophotography this is far from dark enough. Although I’m a casual, opportunistic astrophotographer, very early I’ve learned an interesting fact about what’s considered as dark.

Waiting for the right twilight

I guess you all know what’s twilight – simply said, it’s the time after sunset, the Sun is below the horizon while the upper atmosphere is still illuminated. Yet, it is divided into three phases: civil, nautical and astronomical twilight.

Civil begins at sunset and ends when the geometric center of the sun reaches 6° below the horizon. Nautical twilight is the time when the center of the sun is between 6° and 12° below the horizon. In general, nautical twilight ends when navigation via the horizon at sea is no longer possible. Astronomical twilight is the time when the center of the sun is between 12° and 18° below the horizon. From the end of astronomical twilight in the evening to the beginning of astronomical twilight in the morning, the sky (away from light pollution) is dark enough for all astronomical observations, even the the faintest galaxies or nebulae.

I’ll leave you to guess which type of twilight and darkness is of the biggest importance to these guys by the telescopes. ;)

Nope, still not dark enough…

If I remembered well, on that particular night, the 18th of August, the astronomical darkness began around 11 PM. Well, after it started, my camera started to get busy and it’s sensor started to melt :)

In the far back of these two photos silhouette of mountain Velebit is visible, that’s the view to the south. Yellow light pollution is from the highway. I didn’t mind that much those lights because as much as they are unwanted, they still made the photo a bit more colorful. That’s my tent in the front part. My mosquito-free space for the night. At least i thought so :))

Setup for both of the Milky way photos:

• Camera: Canon 5D mkII
• Lens: 17-40 f/4 L @ 17mm i f4.0
• ISO: 3200
• Exposure: 42 sec
• Processing: Nebulosity 3, Photoshop

My tent looked really nice under the milky way, though. I had put a small red light inside, to make it visible and comfy on the photos.

Also the red light is another first thing you learn when you’re there with astrophotographers: you never walk around or do anything with the regular white flash light. Or any kind of strong light. You might accidentally point it into someone’s eyes or telescope. That’s why I prepared and took my bike’s rear light off to use it as the flashlight (since I didn’t have anything more appropriate).

After I took all those Milky-way-camping photos, it was just about time for the real thing. I was in dilemma: to shoot time-lapse or to shoot star trails. The decision was star trails, for two reasons: first, never before I made a single stair trails photograph so it was a bit of a challenge, and second was there are so many fascinating time-lapse videos of milky way in stunning locations, mine would look like a bad attempt. So, star trails it was.

I asked for a couple of advises from the guys, set up my remote control, exposure, the composition and began shooting.

Setup for star trail photo:

• Camera: Canon 5D mkII
• Lens: 17-40 f/4 L @ 17mm
• ISO: 400
• Exposures: 52 x 5 minutes – total of 260 minutes (4.3 hours)
• camera was controlled by the remote control set up for 5 minutes exposure
• and that’s it!

Since my camera’s sensor is very prone to heating and even after 10 seconds of exposure it shows very large amount of hot pixels – no matter how low ISO value you put. Now you can imagine how it looked like after 5 minutes of one and more than 4 hours of total exposures – the poor sensor thing must have melted inside. :) Anyhow, I was already prepared for the heavy processing and noise removing afterwards so I was not discouraged. Ok, take in account that summer temperatures do not do good to any camera sensor. Astrophotographers all had their cameras modified, with extra cooling systems for the sensors. Heating is a major problem for any kind of long-exposure photography anyway.

Nebulosity 3 software did it’s job (thanks to Filip for for the expert job in noise cleaning) in removing ugly color and light noise so the final result turned out really smooth and noise-free. The exposures were then stacked in StarStax – free and very good software for simple stacking star trails photos. After the stacking, final result was processed in Photoshop.

And here is the result, I’m very happy with it:

Light pollution from the distant towns and highway again did it’s job in coloring the photo (as much as it is unwanted otherwise). I like it this way. Also, trails show really good how different the temperature of the stars is, even though they all seem white when you look into the night sky.

The shooting ended when the sky already began to shine from the east. Some stars were still there.

May I guess that here already the civil twilight had begun? :))))

I wasn’t really sure, but the heck I was sure I could not wait to get home to go to sleep.