In a biting, cold north easterly wind, I managed to photo the three birds, nice and close! The wind was again blowing straight into the face of the hide, so strong at times that we had to close the front hide-flap. The light was reasonable and I managed to achieve 250th sec at F/4. After my first week of using a 600mm F/4 lens and 1000 + shots the wiser, I am pleased with the results. The size, length and weight of this lens should not be underestimated. It is a beast and some considerable size larger than the 500mm of Canon or Nikon. Its' most obvious requirement is high shutter speed. Anything lower than 125th sec is a waste of time resulting in every image out of focus. Thus, I can say that in these dull autumn/winter days, the rule of thumb is high ISO and aperture wide open!