Dust Dust Dust!
If the lens change was needed for the first shot - then it was really worth it! Very nice.
I'd however rather try to use an ND filter to avoid stopping down to more than F10 or so on the A77. You'd get more detail, and also make dust spots less visible.
|_F0A5334-Edit_small by Dester Wallaboo|
from Open Air Fashion Photography
|Feed me, me, me, me, me by Denjw|
from Attention-Seekers in Nature