IRN family is equipped with a photocell.
It is a twilight sensor suitable to automatically switch on and off the illuminators, with adjustable threshold values.
To set the desired light level both products are equipped with a specific trimmer positioned closed to the cable entry, behind the closing cap.
Please never touch the photocell for any reason since this will irreparably damage the sensor and alter its gasket causing water/humidity problems inside the product.
Always use the dedicated trimmer to adjust the luminous level, which is anyhow factory set in the middle range at about 50lx and so suitable for most applications.