1.1.1 Optimal image with the dome/front glass
Axis focus mechanism and especially the autofocus are optimized to work with the dome/front glass coming with the camera only. Using either a different or no dome or placing the camera behind additional glass constructions could affect the focus performance.
1.1.2 Dirty or scratched dome bubble and front glass
A dirty or scratched bubble/front glass will affect the image quality, making it especially hard for the autofocus. For some PTZ devices it is always good to test on different areas of scene/dome areas and detect if the result is the same across different dome areas and zoom levels.