Stains on glass lenses or glas domes

Nauticam glass lenses are crafted of specially formulated low dispersion optical grade glass, ground to the most demanding standards.
These exceptional measures are enhanced by internal anti-reflective coatings that effectively reduce common optical issues such as:

* Chromatic aberrations
* Coma
* Spherical aberration & field deformation associated with underwater macro photography using traditional magnifying lenses.

These optics are assembled in a rugged hard anodized aluminium housing, and nitrogen purged during assembly to eliminate fogging.

But in order to work well, it is important, that you treat your glass lens properly.
The best way to clean these are to rinse them in fresh water, then completely dry with a synthetic fiber cloth shortly after the dive.

The lenses do not like water to dry on them after a dive as the hardness (in even fresh water), can harm the glass.
So, allowing water to dry on the lens surface – can cause staining.

If your glass lens has been stained, it is unlikely you can clean the glass again.
You then need to get the front lens changed.

Please refer to below info:
https://fotografit.eu/products/349-nauticam-lens-service/