I've really enjoyed my Sigma 28-300 Hyperzoom lens. Recently, the viewfinder image is very dim and doing lot's of internet research leads me to believe the Sigma lens aperture may be stuck. Off the camera and viewing the lens from the mounting side shows the lens aperture at the smallest opening (which is a clue). THe depth of field button on my Canon Rebel does nothing. Swapping with the original Canon lens, the viewfinder image is bright, and the depth of field button operates (opens and closes) the lens aperture just fine. So I'm convinced something is wrong with the Sigma lens, not the camera body.
style="BACKGROUND-COLOR: #000000"Can anyone confirm my analysis? Thanks.