Sundog Details

Astronomical phenomena such as sundogs are a relatively common occurrence. What makes them appear to be so rare is, for the most part, a natural result of something being missed by a pair of eyes that have become accustomed to bright sunlight. They are often there it's just that in the natural glare of the sun your eyes have become blind to them.

The web is rich with numerous sites that include detailed descriptions of the solar optics involved in the creation of a sundog as well as a great collection of photos.

The British site Atmospheric Optics includes some beautiful imagery of the classic sundog halo along with a technically accessible discussion of the the science involved.

The first image in this post is a wide field of view of English Bay at 7:05:56 PM March 26th 2007. The image was taken with my trusty Nikon D80 using a Nikkor AF-S 18-200 mm VR (Vibration Reduction) digital lens at an aperture of f/6.3 (wide). The exposure time was 1/640th of a second at a fixed 'film speed' of ISO 100.

When I first saw the sundog it was so bright and large (thanks to the perfectly positioned cloud-lette) that I thought it was an airship off to buzz the tourists in the downtown core of Vancouver. Two or three blimps descend on Vancouver each year and while the shape of your run-of-the-mill zeppelin is anything but what I saw that evening the technocrat in me initially ignored the natural explanation and went for the man-made one. "Blimp. Gotta be."

This period of disbelief lasted but a few seconds however. Once I'd put the pieces together, in particular the fact that the halo and the sun were separated by 22 degrees, I realized I'd just bumped into the photo-op of the year.

All of the images in this post were manipulated as follows:

1. They were re-sized from the D80's natural resolution of 3,872x2,592 (10 Mpixels) to 1,278x855 (suitable for 8"x14" framing).
2. Mild sharpening was applied to the resized pic to pump the contrast just a touch.

That was it.

Having gone through the images many times I expect more than one sceptic will suspect that a bit of digital trickery was employed to create them. I can understand such a reaction. The intensity of the sundog was such a rare event (I've never seen a better one in 48 years) I can fully understand a sceptical response. However the images are pretty much what I saw that evening and the event is one that for me personally is up there with the months spent watching the great Hale-Bopp Comet of 1997 hang suspended over English Bay. Fortunately this time, unlike the last, I took lots of pictures.