If you are using the sunrise/sunset app, you need to make sure you brought the correct zoom/focus over for day and night. I would check that first.
If your focus is good right now in color and daylight, get the focus and zoom from the utility and make sure that is what matches the settings in the utility.
Next change the day to b/w image and have someone stop a car in the middle of the frame and confirm that the picture is clear and if not hit autofocus or manual adjust focus until it is clear and make sure you take the step count from 20 to 1 or it will be off focus within 10 steps. Then go into the sunrise/sunset utility and get the focus and zoom for the b/w setting and then put that into the night setting.
Also increase the seconds between commands on bottom right of the utility. Some people have experienced that a camera may be slow in accepting the changes from this utility, so this allows it more time to ensure the setting takes. For example, people that also change the zoom going from color to B/W means that the camera has to settle down on the zoom before it adjusts the focus and the smaller time meant it sent the command before the camera was ready. Change this to a higher number.
Some people are lucky that the focus is the same for color and B/W. One of my cams is the same and the other is different. Depends on distance.
Here is a thread that explains in way more detail than you may care about that discusses and shows why the focus can be different for light and
IR light..it is an old thread but unfortunately the cams still suffer from this, but is even more relevant with the fast shutters we run for nighttime LPR.
While reading the forum's threads, I found some posts with complains about soft image while the camera is going from color to IR or the opposite. In this Testing roundup IPC-HDBW4431EP-AS versus IPC-HDBW5431E-Z thread, TVT73 is complaining about soft focus in IPC-HDBW4431EP-AS camera. Here Any...
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