Sigma lens and UV filter
Sure, it is possible, but not likely. For a definitive answer, the next time you are shooting outdoors, remove the filter first and see how the camera responds.
Many will argue for and against the use of a UV filter on a lens. Personally, if shooting conditions warrant it (ocean spray, wind, sand, fingerprints), then I say use one. Otherwise, I leave it off.
|2014_1211_140657AA by old shutter bugger|
from The Bride
|Overloaded by NZ Scott|
from Your City - Delivery Boy
|Barley by Will B Milner|
|APPLE & ROACH by TX Photo Doc|
from Delicious - Unpalatable