The distance between me and the entrance of the tunnel must have been like 6m. But I purposely set the shutter at 2 or 3 stops lower for the light to spill over the silhouette. But before that I manually adjusted the focus to half the distance. Probably that explains the super blur effect. And yah, guess you folks are right. A little sharper would have done it. Thanks for the comments. Will remember the next time.