Getting the focus order wrong is the main reason cameras look sharp by day and soft at night, or sharp nearby and blurry at distance.

1. Back focus first: on a varifocal lens, set the back focus ring so the lens holds focus at both ends of the zoom range. With back focus wrong, the image drifts out of focus throughout the zoom.
2. Commission by day: in good light, confirm focus at both centre and edges. Place a reference object at the working distance so the target you actually care about is sharp — not just whatever is closest.
3. Re-check at night: focus can shift slightly once IR illumination engages, so verify again after dark and enable IR-correlated focus or autofocus assistance if available.
4. Lock the adjustments: tighten the focus and angle locking screws and apply thread-locking compound so vibration cannot shift focus.
5. Fine-tune image parameters: adjust exposure (shutter priority or auto), WDR strength, sharpness and noise reduction in that order. Avoid excessive sharpness, which produces haloing and amplifies noise.

A practical tip: record the final parameters for each position — focal length, exposure, WDR level — so replacements or resets can be restored to a consistent result quickly.