>>4288293The issue then becomes that infrared focuses at a different distance than visible light, which is not as much of an issue as you would think unless you're trying to focus visually.
For live view, most cameras will focus using edge detection, which means that you can leave your focus on the backplane in the visible light area, and if you shoot filtered, live view will focus correctly, while when you're shooting visible light, the IR will give you nice gentle halation that looks cool unfiltered.
This was also my reasoning for not filtering directly in front of the sensor, since that would have required more calibration.
Once you've removed the hot filter (the light blue glass) from the sensor, as you're putting it back together, the D5600 at least (and I'd assume most of the APS-C DSLRs excluding the D5XX series) has a sensor held to the control board with springed screws, so basically you just mount the camera to a tripod with either a ruler or dedicated focus tester and:
>focus>shoot>look>loosen or tighten screws a quarter turn>repeatuntil your focus through the viewfinder matches what the camera shoots
