How to clean fungus from inside triplet lens?

[bendiddley]

Hi all. I have recently acquired a meade 5000 triplet refractor and have discovered there is some internal fungus around the edges of the objective. Does anyone have any advise on how to clean this? Thanks.

[Davey-T]

I'd take it to Meade specialist Steve Collingwood 

Dave

[John]

I agree with Dave. Dismantling, cleaning and re-assembling then collimating a triplet objective lens is a specialised job.

[pete_l]

Is there any evidence that this is affecting the view / images?
If it is nothing more than a cosmetic blemish, I'd just leave it be.

There is a story that exposing the lens to UV will prevent further growth.

[bendiddley]

1 hour ago, Davey-T said:

I'd take it to Meade specialist Steve Collingwood

Dave

Cheers. Will think about getting in touch with this guy. Would be interested to see how its done though, anyone know of any videos or instructions?

[bendiddley]

5 minutes ago, pete_l said:

Is there any evidence that this is affecting the view / images?
If it is nothing more than a cosmetic blemish, I'd just leave it be.

There is a story that exposing the lens to UV will prevent further growth.

I can't see it affects the views but I want to sell it on and think the fungus will make it hard to find a buyer which is why I want to clean it.

[Carbon Brush]

There is a potential problem with leaving it be. Fungus grows.

To slow or stop growth, keep the scope cold and dry.
Live fungus may die. But spores will probably survive.

For now store the scope in the garage or even the fridge (suitably wrapped) rather than the warm house.

Ideally give it a purge using a dry gas like nitrogen or carbon dioxide. Or put a bag of silica gel in the eyepiece section.

There was thread a while back about using UV to kill fungus. But no positive responses about wavelength/time/intensity.

My worry with intense light at shorter UV wavelengths (better to kill fungus) is that you may fade paint or degrade plastic/rubber components that get exposed.
Again I have not heard anything definite. It is just an idea resulting from seeing sunlight degraded plastics and faded paint.

I have successfully dismantled doublet refractors to remove fungus. Isopropanol or Baader fluid are good cleaners.
In both cases the lenses had a thin plastic spacer shim between and screwed into the OTA.
The only alignment precaution I took (probably not needed) was to pencil mark the lens edges to keep them in the same arrangement on re-assembly.

I expect the lens cell on your triplet may be more involved. If so, expert advice is a good move.
 

[jock1958]

I dismantled my Tal 100RS doublet lens to refit a dislodged foil spacer, whilst everything was apart I cleaned the lenses with the Baader wonder fluid etc etc and re-assembled it - however sorting the collimation out was a mission and debatable whether it’s 100%.

As its a triplet I would follow previous advice and get it down to Steve Collingwood. 

[dweller25]

Point the lens towards the Sun to give the fungus a good dose of UV, then send it to a specialist for cleaning and collimating.