How to Find and Photograph Aurora Borealis (Northern Lights)
by Chris VenHaus

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Aurora and Marsh Fog
What causes Aurora?

        Coronal Mass Ejections (CME’s) : CME’s are usually associated with solar flares and prominence eruptions. The corona is a gaseous region above the Sun’s surface that extends millions of miles into space. Amazingly, temperatures in the corona may be up to 200 times hotter than the actual surface of the Sun. Large bubbles of hot plasma within the corona are usually threaded with magnetic field lines that rise up out of one sunspot and arch back to reconnect at another nearby spot. A good analogy would be to envision a net holding down a helium balloon. Sometimes, these magnetic field lines merge and cancel each other out, causing a hole in this “magnetic net”. The result may be as much as 10 billion tons (equivalent to the weight of 27,000 Empire State Buildings) of hot plasma ejected for several hours at speeds approaching 1 to 5 million miles per hour. Due to the sheer speed and mass, the energy released can approach that of nearly 10 million volcanic explosions or 100 hurricanes! When an Earth directed CME cloud collides with our magnetosphere, the electrons, protons, and oxygen ions of Earth’s Van Allen radiation belts become denser, hotter, and faster. The motion of these particles can produce nearly one million amperes of electrical current and disrupt the strength of Earth’s magnetic field enough to allow some of the excited particles to crash into our upper atmosphere, about 40 to 200 miles above the Earth. Oxygen and nitrogen atoms react to the bombardment by becoming electrically excited and emit light. Voila! The world’s largest fluorescent lamp… Aurora!

        Coronal Holes: A large region in the corona that is cooler and less dense than its surroundings, as a result of open or large, weak magnetic fields. A coronal hole’s inability to magnetically confine hot gases allows high-speed solar wind particles to be released. When a high-speed coronal stream is directed towards earth, it may result in moderate Aurora.  

Equipment Needed:

Photographing Aurora doesn’t require a fancy camera body with “automatic everything”. Some people actually prefer using older manual cameras, which have a minimum of battery depleting electronics. When working in cold weather, camera batteries will drain much quicker than normal so keep 2 extra batteries in your camera bag, or suffer the wrath of Murphy’s Law. The same applies to bringing 2 flashlights with fresh batteries.

        Camera Body: A 35mm body with manual selection of aperture (f-stop) and exposure up to 30 seconds will be fine.  A camera with a “B” or bulb setting is also OK. The body must also have manual focus capabilities, or the ability to set the focus to “infinity”. A cable release or an automatic timer is also recommended, and mirror lock-up is useful.

        Lenses: Lenses that allow the most light into a camera are known as “fast” lenses, and have maximum apertures (openings) of f2.8 or wider (“wider” means lower “f” number). Any lens with an aperture smaller (higher f-number) than f2.8 will result in unacceptably slow shutter speeds for most Aurora- unfortunately, this excludes most widely used zoom lenses. For this reason, prime lenses (fixed focal length) are good choices, and may be found at a reasonable cost.
        50mm f1.8 or f1.4 lens Great lens for isolating parts of the Aurora, and stars will appear more prominent within the image.
        35mm f2.0 or 1.4 lens Good, fast lens to catch most of the display.
        24mm f2.8, f2.0, or f1.4 lens This would be THE lens I’d buy first for photographing Aurora. It has a nice wide angle of   view, and allows for longer exposure times before star trails appear.
        20mm f2.8, 2.0, or f1.4 lens May be useful for larger Auroral displays that require an even larger field of view than the 24mm lens.
        14mm f2.8 lens A specialty lens that may produce very dramatic effects during large Aurora displays. 14mm lenses may create circular distortions, and will tilt vertical objects when the camera is angled towards the sky.  

* I have found the best place to buy equipment HERE

        Tripod: We are taking exposures of many seconds, so it is imperative that the camera is mounted on a sturdy tripod, or your shots will look like globs of color similar to your kid’s finger paintings. I also recommend using a nylon bungee cord attached in a “U” shape near the center column of the tripod. Simply step down into the “U”, and your tripod is anchored nicely from light winds and other vibrations.  

        Film to use: Film rated 400 to 800 ISO is ideal. Print film has a bit more exposure latitude while slide film has richer blacks and more realistic colors, in my experience. Fuji & Kodak films are ideal, with each having its own distinctive color palette. I prefer Fuji’s professional line of 800 ISO print films and Fuji Provia 400F. Since you will be shooting ALOT of film, it is best to purchase film cost-effectively. This means ordering via the internet, as you will find the cost to be about ½ the price you will pay at your local camera store. I use THIS SOURCE for my film and new equipment purchases.

        Filters: Avoid using any filters, even haze or sky filters. They will degrade the quality of the image.

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"Brilliant Aurora"

Determining when Aurora might be visible:

Waiting for an event powerful enough to cause a significant geomagnetic disturbance is the most difficult part of hunting Aurora, especially in middle and lower latitudes. Be prepared for long hours waiting in the dark and make sure to bring plenty of coffee! Don’t get discouraged if you drive out to your spot and don’t see anything- this is quite common. I have found the most photogenic Aurora to occur between 2 hours before and 2 hours after local midnight. On rare occasions, I have witnessed storms lasting all night, and only faded due to early morning twilight. Visibility of the Aurora may wax and wane throughout the night. Patience is key….

        Predictions and general information:
        Solar Terrestrial Activity Report
        Find your geomagnetic latitude
        Current Space Weather

        Real-time information and alerts:
        My favorite site for receiving alerts and real-time updates is: The text messaging service is outstanding. It allows you to set parameters on when you want to be notified via a cell phone or pager. It’s the ultimate “Heads-up! Aurora might be coming your way” service, in my opinion. There have been numerous times when I’ve been 3, 4, 5 hours from home deciding whether a storm might begin or has ended. My decision was easily made by a real-time alert.

Putting it all together:

If you monitor the above sites, you should always have a 1 to 4 day lead time to prepare for the possibility of Aurora. I say possibility because even the most violent solar events can sometimes be “duds” when they hit Earth. The reason for this is that we need one more element to produce Aurora: a southward tilt in the Interplanetary Magnetic Field (IMF). The IMF is a part of the Sun's magnetic field that is carried outward into interplanetary space by the solar wind. Bz measures the extent we are above or below the thin boundary separating the IMF’s fields. This thin boundary between the opposite magnetic fields is known as the heliospheric current sheet. The current sheet is tilted due to the difference between the Sun's rotational and magnetic axes, which is similar to the difference between Earth’s rotational axis and magnetic poles. In addition to being tilted, the current sheet is also warped. The result is that Earth’s magnetosphere is regularly, periodically being influenced by either one of the opposite magnetic fields of the IMF. To what degree we are entrenched in a specific polarity by moving further above or below the current sheet is measured by Bz. The range of values for Bz is + 50 to –50, with negative numbers indicating a southward tilt to the IMF. In my experience, If the Bz is between –20 and –50 nT, then there is a good shot the southward tilting IMF will partially cancel Earth’s magnetic field at the point of contact. The door has been opened, and Elvis has entered the building! If there is sufficient energy in the solar wind, then those oxygen and nitrogen atoms will start doing their dance, and you’ll get a nice show.

Determining the time of a shockwave arrival, and whether the IMF will be in a favorable position to allow Aurora is as much an art as it is science. These predictions are usually made with a 12 to 24 hour margin of error and are becoming increasingly more accurate, but there is still room for improvement. It is a good bet that if we are hit with a significant shock wave, and the Bz is substantially southward, visible Aurora will be produced in middle and possibly lower latitudes.

Locating the best places to view/photograph the Aurora: You’ll need a very detailed map that includes areas within comfortable driving distance from your home. I use an Atlas/Gazetteer. Most Aurora displays will not be visible within urban areas due to light pollution. I try to find an area on the map that doesn’t have medium or large towns/cities any nearer than 60 to 90 miles in a 90-degree northward view from my desired location. This is a lot tougher than it may appear. Strong displays might be seen in spite of all the light pollution in cities, but such displays are rare. During major storms, if you are far enough north (for people living in the Northern Hemisphere), the display may actually happen right over your head, or even to the South of you, so have a back-up spot available.  

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"Aurora Fish"

Technique and exposure:

        Focussing: Set your camera to manual focus. Rotate your focussing ring on the lens to “infinity”. The infinity mark on some lenses is not accurate- so make sure you check your true infinity focus point before actually going out on a hunt. It is also a good idea to verify the focussing ring is in proper position after every roll you shoot, and after every lens change. Some have suggested using rubber bands to lock the focussing ring, but this is not foolproof either. Disastrous results may occur if you are wooed into a sense of false security, only to find that the 13 rolls of film you shot were all out of focus. Don’t ask me how I know this… :-)

        Exposure Settings:

            Method 1: (When using 800 ISO film)
            f1.4= 8 seconds
            f2.0= 15 seconds
            f2.8= 30 seconds
                 * These are baseline exposure times that should be the center point for bracketing your exposures in ½ stop increments, plus/minus one stop. A “stop” means doubling and halving the exposure time. Very bright, or high-latitude Aurora would need slightly faster exposures than these times. Dim shows or lower latitudes would need slightly longer exposures.  

            Method 2: Use your camera’s spot meter for bright Aurora by metering on the brightest part it and double the indicated “proper” exposure time. Use that for a baseline, and then bracket plus/minus one stop in ½ stop increments.

        Firing the shutter: It is best to use a cable release or automatic timer on your camera when firing the shutter. This keeps movement of the camera to a minimum. It is also advisable to use the mirror lock-up function on your camera to avoid movement from the motion of the camera’s mirror “slapping” against the body.

        Avoiding star trails: Some of the best Aurora images I’ve seen include bright, crisp stars in them. To avoid star trails (caused by the Earth’s rotation), I use the following formula: Take 600 and divide it by the focal length of your lens. The result is the maximum exposure time (in seconds) before star trails will start to appear. Example: A maximum exposure for a 24mm lens would be 600/24 or 25 seconds. Slightly longer times (+50%) may be used for less critical work.
        Fast Aurora vs. slow aurora: Slow-moving Aurora is more photogenic and easier to expose for than fast moving or pulsating Aurora. Wider apertures (f2.0 or wider) or fatsre film (800 ISO +) will be needed to record fast Aurora on film.

        Aurora during moonlit nights: Although it is more difficult to see Aurora during heavily moonlit nights, it can make for an interesting effect since you will be able to get more detail in the foreground elements.

        Avoiding Bears and other critters: Keep any food you bring in sealable plastic baggies. The last thing you need is to have a hungry bear smell your goodies and “mess with your head” while you are waiting for Aurora’s to appear.

Aurora myths:
Myth #1: Auroras make sounds- There is no scientific evidence to indicate Auroras make audible sounds.
Myth #2: You have to live far North to see Auroras- Auroras have been seen as far south as California and Mexico in North America. This occurs during major storms. There is also “Aurora Australis” which occurs in Earth’s Southern Hemisphere as an almost mirror image of what happens in the Northern Hemisphere.
Myth #3: Auroras only occur during Winter- Auroras may occur during any time of the year.
Myth #4: Major Storms only occur during Solar Maximum- Solar maximum is the peak within the 11-year solar cycle when sunspot activity is at its highest- a result of the Sun’s magnetic field reversing polarities.  There is strong evidence to support major geomagnetic storms occurring any time during the solar cycle, with frequent activity when the peak of the cycle is actually abating.  

For more information on Auroras: CLICK HERE

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"Aurora and Me"

About the Author:
Chris VenHaus is the owner of VH Audio in North Prairie WI. He is also a photographer who specializes in Landscape, Aurora, and Weather Photography. To see his photography click here

All content on this website copyright: Chris VenHaus 1997-2003