The minimum focus distance of the 600mm lens required me to move the blind farther away from the feeders. The wary blue jays, difficult to photograph with the 400mm, seem to appreciate the extra personal space.
The 600 presents its own set of challenges. Quarters are cramped enough inside the small blind and adding the big lens makes it even more so, but the biggest problem by far is locating the birds through the lens. At the close distances necessary for frame filling shots the field of view through the finder only covers a few inches and for the most part that is blurred because of the shallow depth of field.