The Waterproof Case fogs up inside causing the recorded images to appear foggy and blurry.

Fog formation can be avoided if you insert the camera into the Waterproof Case/Underwater Housing in the place where the temperature difference is small, and the air is dry with low humidity.

Since the Waterproof Case/Underwater Housing is sealed when it is closed, if the humidity inside the Waterproof Case/Underwater Housing is high, fog is formed depending on the difference of the temperature inside and outside the case.

Fog may also be formed if the lens part of the Waterproof Case/Underwater Housing is exposed to cold air, because temperature difference occurs.

To avoid fogging 

• Insert the camera in the Waterproof Case/Underwater Housing in a dry place with low humidity.
• Insert the camera into the Waterproof Case/Underwater Housing where little change or no difference in temperature occurs.
• Fog formation can also be avoided by using the AKA-AF1 Anti-Fog Insert sheet (sold separately).

Additional information on using an anti-fog sheet (AKA-AF1) is available from the following links:
https://support.d-imaging.sony.co.jp/www/ac_portal/features/akaaf1/en.html