Help, skywatcher 80ed fungus problem!

[Turbocoo]

Hi all 

Really need help here. My old skywatcher 80ed has developed a couple of fungus branches on the inside of the rear cell!

Any advice on how to get at this to clean it or should I send the whole cell off to a specialist. 

Thanks 

[Stuart1971]

Shining a good UV light on it for a few hours will at least kill it, and stop it spreading anymore, then you can clean it yourself with some Baader wonder fluid, assuming you can remove the cell and get to it, and also as long as it is a removable cell and won’t screw up the collimation….

[Turbocoo]

3 minutes ago, Stuart1971 said:

Shining a good UV light on it for a few hours will at least kill it, and stop it spreading anymore, then you can clean it yourself with some Baader wonder fluid, assuming you can remove the cell and get to it, and also as long as it is a removable cell and won’t screw up the collimation….

Thanks, I have both uv light and baader fluid, it's separating the two lens that bothers me. Wonder if anyone had disassembled an 80ed lens cell 

[doublevodka]

On 03/05/2023 at 22:39, Turbocoo said:

Thanks, I have both uv light and baader fluid, it's separating the two lens that bothers me. Wonder if anyone had disassembled an 80ed lens cell 

Had a read online and can't find any guide for taking the cell apart itself so I don't think many have tried.

However, it does look like the whole cell can be removed in one piece so you can at least get to the rear of it without affecting collimation, pinching the optics etc.

The dew shield is friction fit, the cell itself unscrews from the tube, it may be tight, and be careful not to cross thread whilst reassembling.

Decent guide on cleaning here - https://www.skyatnightmagazine.com/advice/clean-a-refractor/

The primary piece of advice, slowly and carefully! and if in any doubt send it to a specialist for cleaning

 

[NGC 1502]

The Skywatcher ED80 cell easily unscrews as a unit.  As mentioned, when reattaching be careful not to cross thread. Removing and reattaching the cell as a unit won’t affect collimation. With the cell removed this gives access to clean the back of the inner lens element.

If the problem is between the lens elements it’s a very different situation. Perhaps consider contacting a specialist repairer  like the well known Es Reid.  If you’re feeling brave you could DIY.  An adjustable lens spanner to engage the holes on the front retaining ring would be a good idea. Note the orientation between the 2 elements plus the orientation of them with respect to the cell. Note any spacers.  Pencil marks will help. Go carefully and methodically and don’t rush.

Finally please understand you can easily mess up. If it were me I’d consider using it as is, or if you can’t live with that contact a specialist as previously mentioned.

Hoping you sort it👍