Possible reasons and solutions:
1) Unmatched lens mount. There are two types of lens mount for box cameras, respectively are CS mount and C mount, the lens and camera must be matched with the same type.
2) Use Focus in / out to control the Clarity.
3) Check whether the lens or housing gets dirty.
4) In strong light condition, please select electronic iris as the lens type.
it’s also suggested to send a snapshot of the picture quality as well as the full device model to firstname.lastname@example.org so that we can help you better.