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.
|Sit on rainbow by frapeace|
|Icelandic landscape by BoDrey|
from Best Landscape of the Week 1