Hi Frode
I have seen your images on my phone, will look at them on laptop later
You have great opportunities to capture great subjects.
Question everything, a satisfactory outcome will arrive.
I had been given a explanation, as to why a lack of contrast in the chosen frame will effect final subject sharpness.
When you put a single point AF on a subject and keep the subject in focus as the shutter is released, the camera is working only on information supplied from one focus point,so does mot have any confusion in how it processes the supplied capture.
In dynamic range AF the camera will track the subject using multiple focus points, what the photographer thinks is the in use focus point does not mean the camera is selecting that point.
The more there is a lack of contrast in the frame, the more the focus points will hunt, trying to find a focus, so a image can be captured that can appear soft, a image can be captured that is sharp, or the camera may retire itself from trying to AF. The more contrast between subject and backdrop the more the camera understands how to track the chosen subject.
As I have said I am working towards maximising my 400mm experience.
My explanation to you is the result of some other my own recent raised questions.
Another small thing that might be of interest to you, is using a tripod in a hide.
If the hide has a internal bench of about 800-900mm in height with the viewing hatches above the bench
A tripod can be set up with two of the legs spread to a V, left at their shortest adjustment.
The two legs can be rested on the bench with the feet resting on the wall.
The single remaining leg will have the foot on the floor. The leg can be height adjusted, until the mounting plate is horizontal. This makes a rigid support, and will usually project the objective lens slightly outside of the hide.