Vintage classic camera viewfinder
My Zeiss Ikon Tenax II, Robot Royal II and Robot Royal III viewfinder all have mould /fungus inside
It is harrmful to the eye looking throu these kind of mouldy viewfinder.
Cleaning may not remove 100% mould.
My solution is to avoid using these direct view finders, instead attach a hotshoe mount waist level finder to these cameras
Read responses in photo.net