Spring Ice - Corners slightly darkened

Artist: J.A. (Tony) Hadley;
Exposure Date: 2011:03:22 19:03:30;
Make: NIKON CORPORATION;
Model: NIKON D300;
ExposureTime: 4/100 s;
FNumber: f/11;
ISOSpeedRatings: 200;
ExposureProgram: Aperture priority;
ExposureBiasValue: -6/6;
MeteringMode: CenterWeightedAverage;
Flash: Flash did not fire;
FocalLength: 10 mm;
FocalLengthIn35mmFilm: 15 mm;
Software: Adobe Photoshop CS5 Windows;