>>3624145That's the best you did to mitigate it. Corner performance and vignetting tends to be worst when at wide apertures. 1/13 sec is the thing that may have caused motion blur. It's difficult to judge from resized image.
When in low light, exposure times will be lower and shutter speeds will drop, first thing that you do is shoot wide open. Then you increase iso. But iso decreases sharpness and dynamic range, so it's the last resort.
From shutter speed and iso I assumed it's handheld. If you had tripod. You'd set iso at best dynamic range value. Iso 100 or 200. Aperture f8 to f11, depends on how lens performs, and then shutter so image would be exposed properly.
