What settings should I use to photograph aurora borealis with a wide angle f/4 lens?

Question

I've tried my first night photography of the stars last week. Most articles I've seen were recommending a fast lens, fully opened, @ ISO 800 and about 20 - 30s exposure, etc. Unfortunately, my only "fast" lens is a 50mm f1.4 which was fine but not as wide as I would have liked.

There is a strong possibility of aurora borealis tonight and I would like to use my wide angle lens (Canon EF 17-40mm f/4.0 L USM) With maximum possible aperture of f/4.0, what settings should I use to produce reasonably noise free photo. I would like to omit star trailing if possible.

I will be using a Canon 60D DSLR.

Answer 1

I could make an educated guess..

Consider this picture, its EXIF data says exposed for 5 sec @ f2.8 at ISO 1600, ignoring the focal length and considering that you said most articles recommend shooting @ ISO 800 using max aperture (in your case f4) you should set your exposure for 20 seconds.
@ISO 400, shutter speed needs to be 40sec
@ISO 200, shutter speed needs to be 80sec
@ISO 100, shutter speed needs to be 160 seconds
but longer shutter speed might cause star trails.
Then again you can set the ISO to 3200 to reduce the shutter speed to 5 seconds.

Assuming the brightness of the Aurora Borealis is the same as in this picture.

I also suggest turning on the custom fuction on the 60D for high ISO noise reduction and Long Exposure noise reduction.

Answer 2

I had luck using all manual settings when I tried to get the northern lights a few weeks ago. I had the Sigma 10-20mm f3.5, so not a radically bigger aperture. I know the lense is a bit soft wide open, so I actually used f5-7.

It wasn't too much activity, mostly the "background" lights, so we needed a very long exposure, and most of the pictures where shot with 30 sec exposure. I adjusted the ISO to get a good exposure, which was mostly around 640. And of course we where using RAW(+JPEG).

If the activity is high, you might want to increase the ISO and try to have a shorter shutter time. When the lights are waving, 30 seconds will be way too long.

Keep in mind how the ISO works on digital cameras. Idiot ISO and Numpty ISO

I was also using a 60D, and didn't activate the high ISO noise reduction or Long Exposure noise reduction. I probably should have done that.

Answer 3

If you want to photograph a green arc that is not moving a lot, then those settings (max aperture, lowest exposure possible like 5-10 sec) are fine. You might have to increase the ISO to 1600. It will have a bit of grain.

But to have perfect pictures, of high activity (fast moving auroras) then you will need a f/1.4 aperture, with the shortest possible exposure time (less than 1 second), probably at ISO 3200, with a very still camera.

But we only have a small experience here in Iceland photographing the aurora.