Originally posted by shuy
i thought starry lights were due to higher exposure, not just aperture size.
By decreasing the aperture size, you'll need a slower shutter speed to compensate. I personally don't use large apertures for my shots unless in low light conditions.

Why don't you follow my link to his tutorial, get his e-mail address and ask him yourself? Otherwise, go out there and start experimenting. You never know until you start trying.