Q: In the night shots is a white ring and the picture is out of focus.
A: The white ring is caused by reflections of the IR LEDs on the upper camera cover. Just push the cover back a bit and the reflections disappear.
Even if you see the white wall or a roof beam in the picture, it is illuminated by the IR LEDs and the picture is deteriorated accordingly. It is therefore best to hold the camera in your hand and position it at night in such a way that there are no reflections at a distance of 3-4m - to give you an idea of what the undisturbed picture looks like. If the image at the installation site is then worse, the cause is usually fast to identify.
Please note that the focus of the camera is wavelength dependent - this means that if you focus the video during the day, it will appear a bit blurry at night - and vice versa. It is best to find a good average there.
With the Full HD camera models, the WDR mode can also lead to a blurred image: