[reeftool]

I have had starbursts on night shots at f/6.7 as on this shot of Lake George last summer. My main goal on this shot was just to get it as I was hand holding the camera. The starbursts added a nice touch I didn't expect.

[Joe Nation]

Can anyone explain why there are 14 points in the star? The DA15 has 7 aperture blades, if it had 9 would there be 18 points?

[ihasa]

That's correct Joe. If there's an odd number of aperture blades you get double the points. If the number is even, you get the same number of points, e.g. 8 blades gives 8 pointed starbusts.

[mikeSF]

even number: intersection points of the blades line up radially with the point opposite (overlaps), so the # of light rays equals the number of blades.

odd number: intersection points are offset resulting in double the number of light rays.

someone else can say it better but for example:
6 blades = 6 pt stars (ugly)
7 = 14 pt
8 = 8 pt
9 = 18 pt
etc