All INON port series employ an optical glass lens with multi-coating
A multi-coating optical glass lens is totally different from a simple water-proof glass and is required highest homogeneity and transmissivity, precised refractive index and dispersing property to pursue sharp and clear images after clearing strict quality control including;
Well selected material
Prolonged polishing in manufacturing
Optical performance test
The multi-coating prevents decrease of permeable light to suppress ghost, flare caused by surface reflection.
A lens port without multi-coating will loose approximately 5% of total transmitted light by reflection due to difference of refractive index between air and a lens at inner surface of the lens.
Also inside of the lens port will cause ghost or flare by inner reflection.
So using a lens port without multi-coating or not using optical glass will inevitably lead to images, especially wide images with whity color tone or less sharpness especially just below surface in backlit.