Forum Login

 

Aurora

World's First Canon EOS-D30 Aurora Borealis Photographs

Aurora, Muskoka Ontario, Canada, October 28, 8:18pm

Photographed with Canon D30 at ISO 400. 15 seconds @ f/2.5 with a Canon 50mm f/1.4 lens. RAW Mode. Long Exposure noise reduction mode ON.

Sometimes you're good, and times you're lucky. Sometimes you're good & lucky. Tonight was one of those special times.

I was at my place in the country (Muskoka, Ontario, Canada) for the weekend, and to do some further testing of the new D30. On the Saturday I had planned to test the D30's long exposure noise reduction mode after dinner. Stepping out onto my deck facing the lake I was excited and very pleased to see the beginnings of an auroral display.

I grabbed the D30, the 50mm f/1.4 lens and tripod, and set myself up in the below freezing evening. Using the D30's special long-exposure noise reduction mode, I took about 25 exposures over a 2 hour period. The best images came from the first hour, as the display started to fade after a while.

Aurora #3, Muskoka Ontario, Canada, October 28, 9:10pm

Photographed with Canon D30 at ISO 400. 15 seconds @ f/2 with a Canon 50mm f/1.4 lens. RAW Mode. Long Exposure noise reduction mode ON.

This frame is the best of the rest. The mauve colour disappeared early in the evening and for the next couple of hours green predominated.

You'll notice the row of dots across the middle of the frame. These are the lights from a passing airplane. The other lights on the horizon are from cottages on the other side of the lake. The red light on the horizon is not associated with the aurora.

Taking  Aurora Photographs

The first thing that you need is a dark sky. Auroras are very faint. Don't even think about trying to see, let alone photograph one from a city. (The very brightest displays can occasionally be seen from suburban areas). The second thing you'll need is an aurora. These are usually best seen above the 45th parallel during the winter months. If you're lucky there will be a new moon or a late rising moon. Strong moonlight can completely wash out a faint aurora display. In August 1998 there was a remarkable aurora one evening that was visible as far south as Boulder Colorado, so go figure.

My country place is exactly on the 45th parallel in north-central Ontario, Canada. It is only 5 miles from The Torrance Barrens, a nature preserve that has been designated by the Provincial government as a dark-sky site.  A pretty good place for astronomy in general and auroras in particular. 

But, since 2000/2001 is at the solar maximum (an 11 year cycle) this is an excellent time to view them from anywhere in the north that has dark skies.

Photographing aurora isn't all that difficult as long as you keep certain things in mind:

The human eye is very insensitive to colour at low light levels. Allow your eyes to adapt to the dark and try and keep lights to a minimum.

Film (or imaging chips) doing time exposures will see a lot more colour and detail that you will with the naked eye. That's what makes photographing them fun.

Use a tripod (of course) since exposures will run between 10 seconds and a minute or more.

Use a fast prime lens if possible rather than a zoom. I used a 50mm f/1.4 Canon stopped down about 2 stops. This gives maximum resolution. Zooms, in addition to being slow are not as sharp as primes when it comes to photographing point-source lights wide-open (such as stars).

Remember that the longer the focal length and the longer the exposure the more chance you have for the stars to start to show trails (because of the Earth's rotation). A fast wide-angle prime lens is the best choice for Aurora photography.

Using the Canon D30

I found the D30 to be a great choice for this type of photography. One needs to use at last ISO 400 along with a fast lens for good aurora shots, and I found the results from the D30 to be comparable in terms of grain and noise to transparency films of this speed. (Using a fine-grain colour negative film like Fuji NHG will produce superior, if less convenient, results.)

It was the convenience that I particularly enjoyed. In the past I've done aurora photographs on film and had to wait from days or weeks before seeing the results. (The nearest E6 lab is over 100 miles away.)  Here I was able to review the images seconds after they were taken and have them onscreen and printed the same evening.

There's one downside to this though. When your eyes are dark adapted the rear LCD is extremely bright and your night vision will be ruined for many minutes afterward. I plan on putting some ND material over the screen the next time,

Custom Function 1 on the D30 allows you to turn on a special long exposure mode. This is then applied to any exposure of over 1 second. The downside is that the exposure time is effectively doubled as the camera will take as long processing the image after the exposure as it did taking the photograph.

What the camera is doing is taking what's known as a "dark frame" and then subtracting it from the image. Explanation: As exposure time increases all imaging chips are subject to thermal noise. Random electrons. Chips used for astrophotography are cooled down to about -20c using a Pelletier cooler to help reduce this noise.

By taking a dark frame (a blank exposure of the same duration as the primary exposure) and then mathematically subtracting it from that exposure, much of this random thermal noise can be eliminated.

Ps: No, I didn't do a comparison on that evening between shots taken with and without dark frame subtraction. I was having too much fun viewing and photographing to bother with testing. Next time.

Processing  Aurora Photographs

No image, whether film-based or digital, properly represents what was photographed without being processed. Please see my article Digital is Not Polaroid for more on this topic and also my article Instant PhotoShop for advice on how best to use PhotoShop to get the highest quality.

Long exposure images, whether from film or chip, are inherently noisy. Two tools in Photoshop that can help mask the noise are Filter/Noise/Despeckle and Filter/Noise/Dust & Scratches. The judicious use of these two filters can be quite helpful. If you get very serious about this there are a number of excellent programs with specialized noise fighting tools contained in programs designed for astrophotography image processing.

Filed Under:  
Essays   

show page metadata

Concepts: Photography, Film speed, Science of photography, Aperture, F-number, Light, Exposure, Shutter speed

Entities: Boulder, Canon, Canada, ISO, image processing, Provincial government, Michael Reichmann, Torrance Barrens, aurora, Ontario, Colorado, PhotoShop

Tags: noise reduction mode, long exposure, image, Exposure noise reduction, Long Exposure noise, dark, dark frame, RAW Mode, Canon D30, 45th parallel, exposure time, prime lens, thermal noise, photographing, long exposure mode, exposure time increases, chip, Long exposure images, faint aurora display, random thermal noise, fast prime lens, wide-angle prime lens, nearest e6 lab, dark frame subtraction, good aurora shots, colour negative film, late rising moon, blank exposure, low light levels, primary exposure, article instant photoshop, exposures, lucky, astrophotography image processing, remarkable aurora, aurora photographs, dark sky, special, Aurora photography, mauve colour