Photographing the corona (aurora borealis)

A corona outburst usually doesn’t last long and there are several ways to capture it. I won’t go into details of using a whole-sky fisheye lens or filming the aurora. Most of you coming to the North (or South) to see the lights have a dslr camera with a wide-angle lens. So, what more is needed?

  • know your aperture, exposure time and ISO
    When being out at night, seeing the aurora gaining in strength, you might be so excited that the camera basics are forgotten and replaced by adrenaline. Be familiar with your camera settings and what the change will do. For example let’s say you are using these settings: aperture 2.8 | ISO 800 | Exposure time 4 sec. If you want to capture more details you need to shorten the exposure time. But what do you need to do with the aperture and ISO? Anything? Indeed you do, otherwise your image might be too dark. In my aurora guide I cover this in more detail.
  • know your camera buttons in the dark
    It is exciting to see the dancing lights in the sky and you might press the wrong camera button which messes up the photo. Taking out the flashlight, checking and correcting might take just long enough for the corona to pass. Knowing which buttons/wheels change the ISO, aperture and exposure time helps a lot.
  • follow the aurora develop
    As you’ll see in the photos below, aurora will change quickly and – while positioning the camera, etc – it’s good to keep at least one eye on the sky. Which leads to the next point
  • be ready to ‘shoot from the (tripod) hip’
    when the corona opens up it is not a fixed point in the sky, it moves around. If you are superfast, you can use the camera’s viewfinder to point at the corona. For me, the best way was to turn the camera approximately right. And often that works. It’s perhaps tricky to explain in writing, easiest is to show you during one of my tours.
  • check the photo for highlights
    just before the corona the intensity of the lights is often rising, resulting in blown out highlights of the next image. Check the photo from the screen and if there are some white areas, you want to adjust either the aperture, exposure time or ISO.

That’s about it, if you want to share your experiences or have more ideas, points to remember, I’d be happy to read your comment and let’s discuss!

The corona photo series below is taken within ~70 seconds.


Copyright: Thomas Kast

A strong aurora outburst with a starting corona at the top

Copyright: Thomas Kast

9 seconds later – One more photo into the same direction, notice the purple-green rays on the top right corner. Time to point the camera upwards.

Copyright: Thomas Kast

14 seconds later – the corona is about to unfold, rays in all directions, what a rush!

Copyright: Thomas Kast

12 seconds later – Boom, we have lift off. It’s like looking into the soul of Lady Aurora

Copyright: Thomas Kast

15 seconds later – The end is nearing, the structured rays get washed out and the puple is almost gone

Copyright: Thomas Kast

18 seconds later – the show moved on, see the rays on the far right



Fox ­fires – an Aurora Borealis guide V: Links

Part I: Introduction and terms
Part II: Expectations
Part III: Preparation is everything
Part IV: Photographing auroras

The final part of my Aurora Borealis guide is a list of websites. There are a lot of pages with useful information, here are some of them.

Magnetogram in Sodankylä (Finland)
Magnetogram in Tromsø (Norway)

Webcam in Kiruna (Sweden)
Webcam in Sodankylä (Finland)
Webcam in Tromsø (Norway)

Webcam collection from Aurora Service (Europe)
Webcam collection from Auroras Now! (all in Finland)
Webcam collection from
Webcam in Abisko (Sweden) – currently under maintenance

Aurora oval (20 minute forecast)
Kp-index prediction for the next hours
Kp-index Map Europe & Asia
Kp-index Map North America

Aurora Service (Europe) – auroras and sun activity for Europe – auroras and sun activity
Auroras Now! – aurora forecast & webcams (in Finnish)
Aurora forcast from GI Alaska
3-day Report of Solar and Geophysical Activity (NOAA)
Space Weather Prediction Center (NOAA)  – solar activity, meteors, comets, etc – all about the sun

Moon phases, rise and set times
Sun Calculator for your location

So that’s about it. I might add some mobile apps here at some point too.

Hopefully you found some useful tps in this guide and are able to use them soon!

Wishing you colorful nights,

Copyright: Thomas Kast

Midnight magic

Fox ­fires – an Aurora Borealis guide IV: Photographing auroras

Part I: Introduction and terms
Part II: Expectations
Part III: Preparation is everything
Part V: Links

If you see the aurora borealis for the first time, there is a good chance you will be so amazed and thrilled that your photos won’t be what you hoped for. With any bad luck you’ll have the settings figured out just when best part of the show is over. Reading through this section should help you to be ready for aurora photos.

Photo equipment
– Tripod: To photograph at night you will need a tripod to minimize camera shaking. Handheld aurora photos will not be what you want.
– camera: your camera should have the option of manual focus (see next paragraph why) and have a manual mode where you can adjust aperture, exposure time and ISO separately.
– lens: you need a fast lens (wide aperture, small f-number like f/2.8 or faster. F/4 is still ok) to make the most of the little light available. Also, auroras often stretch all over the horizon. To capture a big part of it, you want to have a wide-angle lens (24mm or wider. In some rare cases 50mm is ok)
– remote control: to further minimize camera shaking, take a remote control with you for taking pictures without touching the camera. Many cameras have a delayed shutter mode (1sec..20sec) which also helps to reduce shaking.
– spare batteries: in cold weather your batteries will discharge quite fast, so it is good to have at least one extra with you. Using hand warmers you can revive the batteries to get the last bit of energy out of them (tip from Jake D., thanks buddy).
– sun hood: at times you will be in damp weather or it will be windy. Moisture can be a problem then for your lens. One way to solve this is putting the sun hood onto the lens.

Manual focus
If you are in a dark place to watch auroras your camera‘s auto focus will not work because there isn’t enough light. So you need to turn off auto focus and focus manually using the manual focus ring! To get e.g. trees or mountains on the horizon sharp, you need to focus on infinity.

Copyright: Thomas Kast

Focus ring on the lens

To achieve this manually there are a few options:
– some focus rings have a hard stop at infinity. Usually you will find the sharpest image by turning the manual focus ring all the way until it stops and then turn it just a tiny bit back. To be sure, do that in day light and make some test shots. Then remember the right position or mark it.
– other focus rings do not have a hard stop, so what you can do is to focus on a bright star using live view. Live view means seeing the scene you try to capture through your cameras display. Many cameras have that option and you can zoom into that picture. Try to find a bright star and point your camera towards it. Via live view, zoom into the display to see that star as big as possible. Once there, turn the manual focus ring until you find that star to be at its sharpest.
– say you can’t find a star. Point your camera towards a rock, tree or anything which is about 6-8 meters away. Then switch on your flashlight and point it at the same object. With a strong flashlight you may be able to use your cameras auto-focus. Once the image is sharp, turn off auto-focus and don’t touch the focus ring. If the light is not strong enough, follow the above steps via live view.
– if you don’t have live view your only choice is to do some trial shots and zoom into your shot and see if the photo is sharp as you wish. If not, adjust and start over until you find the best result. What you also can do is use the auto-focus during daytime, then switch of your camera and place it carefully in the camera bag. This works sometimes but is certainly not the best way.
It’s difficult for me to tell you which method is the best for you without having your camera in my hands. So get familiar with your camera settings and be ready to try out some of these. To do that you – of course – don’t need auroras, so you can do it at home beforehand.
One more thing, if you have a zoom lense and you do zoom, you may need to re-adjust your focus. Always check your images via the display if they are sharp.

Camera settings
Photographing auroras is all about finding the best combination of aperture, ISO and exposure time. All three are dependable on each other. In the end it’s up to you to experiment and come up with the best result.

Copyright: Thomas Kast

Camera display with 10 sec exposure, apterture f/4.0 and ISO 1600

With short exposure times you can ‘freeze’ more details of the aurora. The faster your lense is (wider open, small f-number) the more light gets into the camera. This will allow for shorter exposure times to capture more aurora details.
High ISO settings also allows for shorter exposure times and/or wider aperture (smaller f-number). But for many cameras high ISO results in a lot of noise.
Let’s say the following settings result in a good image:
Aperture 4.0 | ISO 800 | Exposure time 10sec
If you want to shorten your exposure time to freeze some aurora action, there are two things to do: Aperture to 2.8 or ISO to 1600. Both will cut the exposure time in half to 5sec.
If you want less noise you can do one of these: Aperture to 2.8 or exposure time to 20s. Again, both allow you to set your ISO to 800.

Moon phases
The moon light will change the nature of your capture photo. To get the best mix of landscape and auroras a quarter to half of the moon should be visible. This will give enough light to capture the landscape and still be dark enough to preserve a lot of details and colors of auroras.
At Full Moon the landscape will be very bright and photos will look like daylight photos, which can be very cool. Auroras however will suffer as many details will be overpowered by the moon light.
At New Moon your camera will see all the details of the auroras, you’ll love the photos. Capturing the landscape nicely is a struggle. It’s so dark you will have to push the ISO up and be ready for noise in the photo.

Copyright: Thomas Kast

No moonlight in total darkness.

When photographing in a group
Having led quite a few groups to shoot aurora photos, I’ve seen some ‘actions’ which wasn’t liked by others. Many are so excited to take aurora photos, they don’t think about anyone around them. For example:
– to see the camera dial, some use a flashlight and point to the camera. That often means it’s also pointed into the scene and so destroys someone else’s photos. Pointing the flashlight backwards near the camera will provide enough light. Also it is polite to ask other if it’s ok to switch on the flashlight.
– when changing the place of the camera, some just walk in front of other cameras or even place their camera right in front of someone else. Walking behind other cameras does the trick. If there is not much space, speak up and tell the others what you do. In that way they’ll be ready.

Copyright: Thomas Kast

Don’t point your flashlight like this

Copyright: Thomas Kast

Group of photographers next to each other

Some more things
– unless you shoot in RAW and post-process on your desktop or laptop, you want to get the right white balance at night. If you have only presets (sun, shadow, etc) try them out and see which works best. If your camera can adjust Kelvins, go somewhere cool, below 5k.
– when you check your image at the cameras display in the dark, photos will appear brighter compared to watching them on your screen in daylight. Use the histogram and make sure the right end is at least somewhere near the middle. If all light is on the very left your photo is most likely too dark.
– at times you can see star trails in photos of the night sky. Sometimes it is wanted and sometimes not. To avoid star trails all you have to do is follow the ‘500 rule’. Divide 500 by your focal length and the result is the maximum exposure time. For example, let’s say you use 16mm full frame, the maximum exposure time without star trails will be 30 seconds. One more example, for 16mm on a cropped frame the maximum will be 20 seconds. (16mm x 1,5 crop factor / 500).

Copyright: Thomas Kast

Unwanted star trails in a 30 sec exposure at 24mm

Hopefully this will help you to get some decent aurora photos. In the last part of this guide you will find a list of useful and interesting links.

Fox ­fires – an Aurora Borealis guide III: Preparation is everything

Part I: Introduction and Terms
Part II: Expectations

Let’s go through the preparation from planning a trip right until the search for auroras. If you book a guided tour or all-inclusive package you may ignore most of this part. In case you do an individual trip you may want to read all of it.

Best time to travel
For Northern Europe any time from September through March is good. For North America I think it would be even August through April. Besides activity from the sun, two factors will maximize your chances to see auroras: clear skies and darkness. Between November and January is the darkest time, offering very long nights. Around September/October and February/March the nights are not as long but it is said around both equinoxes the chances for clear skies are best.
Different Moon phases will affect your aurora experience. A Full Moon is usually very bright and overpowers some details and colors in the auroras, but it lightens up the landscape around you which is also very special. With half the Moon visible (First or Last Quarter) or less you get the most out of auroras. The New Moon reveals most details of auroras and you can also see the Milky Way much clearer.

Copyright: Thomas Kast

Landscape lit up by moonlight

What are the best areas to travel to for auroras?
In Northern Europe there are many places where it’s possible to see auroras. Northern Finland, all of Iceland, Northern Norway and Northern Sweden are all good places within or at the edge of the aurora oval. Choosing between these is a matter of preference, I’ll leave that to you. I have no experience with with North America, but the following thoughts may help your choice.
A good decision maker for a travel destination are the Kp-lines of the  Kp-index maps from NOAA (Eurasia and North America). Being somewhere near the Kp=3 line will give you a good chance to see auroras near the horizon towards NorthWest and a fair chance to see them dancing above you. If you go a few hundred kilometers North your chances drastically increase to see auroras dancing all around you, because you are entering the Kp=2 and 1 zone. Remember, strong geomagnetic activity (high Kp-value) occurs less frequent than weaker activity.

What should I pack
Make sure you have the right clothing for the season. Check out the weather forecast. Nothing is worse than seeing great auroras and having to leave because it is getting too cold.
Good, warm clothing is very important. Make sure you protect your head, ears and hands against the cold. Also winter wear for your body and feet is essential. Your toes may start to freeze and you won’t notice it all that much. Once in a warm place, life goes back into those toes. Although that may sound positive, it’s not a nice experience.
If you don’t have special winter wear, you may be able to borrow some from a local tour company for a small fee. Search online and contact them for shoes and/or a warm overall.

Copyright: Thomas Kast

Some shoes are warmer than others.

Besides the basic things, you may want to pack following items:
– thermos filled with hot juice, tea or coffee
– a warm ski mask to protect your face
– re-usable hand warmers and/or toe warmers
– a flashlight or head lamp

I arrived, what now?
Your goal number one will be to find a good viewing spot with two main goals: a wide view and little to no light pollution. If you are in a cabin far away from any villages you have no light pollution problems. Go find an elevated spot or an opening like a field or lake. If however you are in a village I’d suggest you check out your surroundings and search for good spots during day time either by walking, skiing or driving. Artificial light sources as street lamps, car lights or skiing track lights can create problems. If they are in the same direction as auroras, your eyes will not see the auroras as bright. Also your photos will not look as good. If there are some clouds, these light sources will be reflected and your photos will most likely have orange clouds.

Copyright: Thomas Kast

Artificial light colors clouds

When auroras suddenly appear you’ll want to be ready and know where to go. Locals may have good tips for you, so ask them unless you enjoy the search for good spots. Of course you can use an online map service already before you leave or at your accommodation. For me personally exploring the area and finding great spots is half of the fun.

Outside are auroras, what was it I should not forget?
Make sure that the batteries of your phone, GPS, camera etc are fully loaded before you head out for the night. In cold temperatures batteries will discharge much faster.
Do not forget your gloves
Do not forget your beanie or skiing mask
Seriously, make sure you protect your head, ears and hands

Here ends the third part. Continue reading:
Part IV: Photographing auroras
Part V: Links

Fox ­fires – an Aurora Borealis guide II: Expectations

Part I: Introduction and Terms

To have a great aurora experience, it is good to have realistic expectations. Not living in a place where auroras are visible may lead to wrong assumptions. To give you a better picture of what to expect, I will go through some common questions and answer them. As you read through, you will understand that there are many uncertainties in predicting auroras.

Are the colors as strong as in the pictures I’ve seen?
Not often, the colors of auroras are usually much weaker to the human eye. There is one big difference between a camera and our eyes. If we look at the sky for five seconds, the human eye sees every moment once. We may remember them in our brain, but our eye can see only one moment a time and erases the one before. If the camera ‘looks’ for five seconds at the sky, it adds all moments together and creates one image from all those single moments. Therefore the colors are mostly stronger in the image opposed to how we see them.
Trying to photograph auroras in its natural, pale colors and strength would most of the time result in a black landscape because there just isn’t enough light.

Copyright: Thomas Kast

How the camera sees things (developed RAW)

Copyright: Thomas Kast

Here I tried to reconstruct how it really looked like

Are there always multiple colors of auroras in the sky?
No, every night is different. Green is the most common, followed by purple, red and blue. Strong green aurora arcs have often a bit of white/purple at the lower end.

Copyright: Thomas Kast

Nothing but green

Copyright: Thomas Kast

Very colorful aurora during geomagnetical storm

Why are there different colors?
Colors appear when gas in our atmosphere is excited by incoming solar wind. Oxygen then can produce the common green color and also the red in high altitudes. The color depends how excited the gas is. Nitrogen is responsible for blue. At times these colors mix and we can see purple, white, etc.

Copyright: Thomas Kast

Common green with red high above

Copyright: Thomas Kast

Green with white and purple at the lower edge

In what shapes do auroras appear?
Shapes are determined by the strength and speed of the solar wind. Depending where you are to view auroras, some shapes may be more common than others.
Let’s go through some of the common shapes and start with the relatively calm ones, arcs, needles and curtains:
Slow, weak wind might create ‘only’ a very pale, green arc on the horizon which barely moves at all, just like a rainbow. With speed and strength picking up, an arc may be higher up and even travel all the way over the sky. There are also times when you can see multiple arcs, one almost above you and others towards the horizons).
The arc can turn into a curtain with needles rising high up in the sky and travel fast through the arc. I like to call this a curtain because it reminds me of a stage curtain in a theater. Usually I imagine someone is at one end of that curtain making waves.

Copyright: Thomas Kast

An arc stretching over the horizon with some needles.

Copyright: Thomas Kast

A curtain made of countless needles

Copyright: Thomas Kast

A green curtain over the frozen Baltic Sea

Sometimes there is no curtain, arc or needles but a fog-like glow filling half the sky.
Let’s go to the crazy stuff now, spirals, coronas and flickering
Spirals travel from the low horizon upwards and dance in curves. This is often happening with strong solar wind and over in just a few minutes. If the auroras are very strong and you are lucky, you can see a corona opening up right above in the sky. Countless rays spread out in multiple colors. This usually lasts less than a minute. After a corona there is often a kind of flickering, where parts of the sky above are randomly lit up and switched off within split-seconds.

Copyright: Thomas Kast

Spiral shaped aurora with twilight

Copyright: Thomas Kast

Corona explosion in green and purple

Can I see auroras right after sunset?
No, auroras will be visible only once the sun is about 10 degrees below the horizon. Before that, the daylight is still too strong. In autumn there can be twilight at the horizon and auroras in the sky.

Copyright: Thomas Kast

Auroras with twilight on the horizon

Are the lights dancing in the sky all night long?
Not usually, this depends on the strength and density of the particles flowing into our atmosphere. However, a long-lasting strong CME or big coronal hole can produce a show that lasts throughout the night and longer.

Can I see Northern lights every night?
No, it all depends on what is happening on the sun and solar wind leaving. If the activity on the sun is high, there can be auroras for many nights in a row. When the sun is quiet, there can be a number of nights without any auroras.

Can auroras be seen through clouds?
Yes and no, it depends on the thickness of clouds. Through a thin layer of clouds, strong auroras can be seen easily. If the sky is filled with thick clouds there is usually no chance to see any auroras.

Copyright: Thomas Kast

Auroras visible through openings in the clouds

A CME erupted, when can I expect to see auroras?
That depends on a few things. First of all, for auroras to show up, that CME must travel towards Earth or at least near it. In case it does flow towards Earth, impact is usually around 24-72 hours afterwards. However, sometimes there may be no impact recorded at all.
The estimate for time of impact not always correct, sometimes it is earlier, sometimes later. The main reason for it is speed as we can’t know for sure how much the solar wind slows down while travelling.

I read online that there should be Northern lights tonight, is that a guarantee?
By now you have probably learned that there are no guarantees. The best way to know is to go outside and look up. Of course there are tools online which can help you. These include webcams showing the night sky, magnetograms showing how the situation of Earth’s magnetic field and pages showing the expected kp-index or auroral oval. The last part of this guide consists of a list of links.

We are at the end of the second part, expectations.
Continue reading:
Part III: Preparation is everything
Part IV: Photographing auroras
Part V: Links

Fox ­fires – an Aurora Borealis guide: Introduction and Terms

Aurora borealis – just hearing those words make me look outside and check for clear skies. The mystic dancing lights are a big part of my life and with many people asking me questions about them, I decided to write this guide.

Many different stories about auroras have one thing in common: there is magic seeing the lights in the sky. A tale from the Sami people says that a fox is running across the fells of Lapland and its tail whirls up snow high in the air. So it’s not hard to understand why the Finnish word for Aurora borealis is revontulet (fox fires). Being outdoors at night in complete silence and solitary I sometimes wonder if I’ll ever be lucky enough to see that fox..

Copyright: Thomas Kast

Just missed the fox..

This guide consists of five parts and my goal is to help you
– to understand terms which are commonly used
– to have realistic expectations
– to know when and where to go and what to bring
– to capture some decent aurora photos
– provide you with a list of useful links.

After reading through this guide, you will understand that auroras cannot be predicted perfectly. Certain places and nights may proove to have higher viewing probabilities, but there is no guarantee to see auroras in certain colors at a certain time in a certain place.

For me, all these uncertainties make it even more special when seeing Northern lights. Every night is a surprise, you just never know what to expect.

Copyright: Thomas Kast

Auroras are reflected in this calm lake with a satellite flare.



In this section I will go through the most common terms used in connection with auroras. It is not my goal to write perfect, scientific explanations, but to make these terms understandable to everyone with some examples.

Aurora borealis
A display of light in the night sky of the Northern hemisphere. It is caused by charged particles from the sun. When these particles reach Earth, they collide with atoms in our atmosphere and create light in certain colors. Think of it like raindrops colliding with sun light producing a colorful rainbow.
The name comes from the words Aurora (the Roman goddess of dawn) and boreal (the Greek name for north wind). Northern lights is another name for aurora borealis. Auroras (or more correctly aurorae) in the Southern hemisphere are called Aurora australis.

Auroral oval
an oval-shaped area around the magnetic poles, in which auroras might be visible. Imagine you open the tap on your sink to wash your hands. In the sink, the water usually goes around in a circle before leaving through the drain. Depending how strong and how much water comes out of the tap, that circle changes its shape and size. Something similar happens with the aurora oval. Depending on the amount and speed of particles, the oval changes shape and strength.
NOAA Space Weather Prediction Center has developed a model for the short-term forecast (20 minutes). Colored areas show where are possibilities to see auroras, it is however not a viewing guarantee. Here are the links for the Northern hemisphere and for the Southern hemisphere.

short for Coronal Mass Ejection. It stands for a sudden burst of gas (solar wind) leaving the sun’s surface. This mainly happens at sunspots. Imagine an air bubble under water rising to the surface. When the bubble is breaking through the surface the bubble will burst.

Coronal hole
a certain magnetic field in the sun’s atmosphere allows solar wind to stream into space. Instead of a bursting air bubble, imagine a windy day and someone opens a window. Through it comes a strong, steady breeze until the window is closed.

Geomagnetic storm
Occurs when Earth’s magnetic field is hit by a strong CME or a high-speed solar wind. A storm usually triggers bright aurora displays. There are five classes of geomagnetic storms from G1 (weakest) to G5.

indicates the strength of geomagnetic activity. It is numbered from one to nine, with nine being the strongest. A G1 geomagnetic storm has a Kp of 5, a G5 storm a Kp of 9. This number tells us also where auroras can possibly be seen.
NOAA Space Weather Prediction Center has created maps with colored lines for Kp=3, 5, 7 and 9 in it. In that way you can check your location and Kp-value is needed for auroras possibly to appear there. Here are the links for the Kp-index map for Europe and Asia and the Kp-index map for North America.

A graph showing the real-time situation of Earth’s magnetic field. This can be compared to a seismometer for earthquakes. Horizontal flat lines indicate the field is intact while vertical outbreaks are signs for interruptions. Strong vertical outbreaks often tell us that solar wind has arrived and auroras could be seen. As an example, here the link to the magnetogram from Sodankylä, Finland.

Solar cycle
Our sun’s activity is on a maximum once every 11 years or so, often called solar max. During that time the number of sunspots and CME’s are usually high, creating a lot of auroras. Halfway through that cycle there will be solar min, when not much is happening on the sun’s surface apart from coronal holes.
Imagine your own energy level during 24 hours. You may get up in the morning and at some point in the day you are most active. Later, while sleeping, your activity level will tend to be at a minimum.

Solar wind
a stream of charged particles leaving the sun. If Earth-directed it might trigger aurorae

an area on the sun’s surface with a strong magnetic field. That field can stretch into space without being broken. The gas then has more space and therefore heat on the surface is reduced. Because of the lower temperature that area is observed as a dark spot.
To imagine the stretching magnetic field let’s think of children blowing soap bubbles. If blown carefully, the bubble can be held at the ring for a while before releasing it.
For the dark sun spots imagine a metal bar being formed into a sword. It is done when the metal is hot, having an orange glow. Once put into cold water it cools down and is darker.

This concludes the first part; getting started and explaining some common terms.
Continue reading
Part II: Expectations
Part III: Preparation is everything
Part IV: Photographing auroras
Part V: Links

If you have questions, comments or any other feedback, feel free to write!