On 13/05/2020 09:44, Another John wrote:
I've got an old (c.25 years) pair of binoculars which are "hazing" due
to age: I'm assuming that the haze is internal -- the four outside lens
surfaces get cleaned regularly.

I've often looked at doing it, but always chicken out when I start to
unscrew things: is it actually possible to dismantle the binoculars and
clean the inside lens surfaces?

Cheers
John

Well, yes; but there is a risk you will make things worse or not be able
to reassemble them successfully.

A common cause on old optics is the growth of a fungus on the internal
surfaces of lenses and prisms.I believe this can etch the coatings or
glass, and therefore can't simply be cleaned off.

Binoculars are not always easy to dismantle, and it depends on the prism
arrangement. I have not looked on YouTube but since everything else is
there, I assume they will be. That would definitely be my starting point.

At least it is easier to get hold of tools these days.

https://www.amazon.co.uk/Neewer-Came.../dp/B0734PH87W

If they were expensive ones, it is probably safer to trust them to a
specialist. Good camera shops would usually be able to point you to someone.