bulb exposure

i recently took some night scene using bulb exposure and i notice that the lightspots appear in star even i didn't attach special filter,why?

what will the image become if u smear some oily cream on the lens surface?

One common reason for bright spots appearing star shaped is because

of the shape of the lens aperture.

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If you want to smear something on a lens, I suggest using a filter

over the front of it first. That way you won't ruin the lens. Why

don't you try it and see what happens? Some people smear stuff

around the outside edges but leave the center clear for effect.

Sometimes it looks good.