why the black halo??

why the black halo?, its shot with my 55-200 4.5-5.6. seen similar halos in sunset pics. any ways to avoid that?
regards
anuj
Attachment 18798

I really don't see anything. Are you talking around the moon or around the leaves? I don't see anything around the moon.

around the moon....hmmm heres nother one around the sun. someone plz find something or ill have to get my eyes checked. try stepping back from the screen..Attachment 18799

It's a natural phenomenon, not your camera.

APOD: 2006 April 11 - A Sun Halo over Utah