Sensor Dust Anguish
Is this the only zoom you own? If not try it with a different zoom. If the problem persists then I would assume that the mirror box is the issue. If it goes away, I would assume you still have a problem with the lens.
In any case the previous posters cleaning suggestions should work well.
|"Hole in the Wall" by gordonpritchard|
|This is Osterdeich by Olaf R|
from Sports Fan(s)
|Rufous Hummingbird by jdc562|
from A Big Year - birds
|SALUTING by TX Photo Doc|
from - The True Blue American Male - (Portrait in Full Colours Only + A Border)