Fungus advice

[m1dlj]

Hi Folks,

Acquired 17 year old tired looking Meade LX90 EMC 8" recently. Several issues to deal with, most significant being fungal growth on the primary ( see below).

Decided to try cleaning, as leaving it would risk further damage to the coating, so, dabbed surface with distilled water, then dried and finished with isopropyl and a 'lens cloth'. Bit nerve racking, never attempted such before, however, it now looks much better with no sign of pitting.

I know the scope has not be used for a while and suspect it was stored in a barn. Had to dismantle and clean the Autostar Hand Controller as several keys were not working. They work now if you press hard enough, but the keypad is badly worn.

Q. Does anyone have any experience dealing with fungus like this? What exactly is it, and why grow on the mirror? What else can I do to prevent a recurrence?

Looking forward to trying it out, I'm sure there's a few more sessions to be had from it.

Ray

 

 

 

 

 

[knobby]

My Dad used to use mild fairy liquid to soften / loosen then carefully wipe while running under hot water, finish off with white vinegar. That was on camera lens though, but possibly similar ?

[WanderingEye]

1 hour ago, m1dlj said:

Hi Folks,

Acquired 17 year old tired looking Meade LX90 EMC 8" recently. Several issues to deal with, most significant being fungal growth on the primary ( see below).

Decided to try cleaning, as leaving it would risk further damage to the coating, so, dabbed surface with distilled water, then dried and finished with isopropyl and a 'lens cloth'. Bit nerve racking, never attempted such before, however, it now looks much better with no sign of pitting.

I know the scope has not be used for a while and suspect it was stored in a barn. Had to dismantle and clean the Autostar Hand Controller as several keys were not working. They work now if you press hard enough, but the keypad is badly worn.

Q. Does anyone have any experience dealing with fungus like this? What exactly is it, and why grow on the mirror? What else can I do to prevent a recurrence?

Looking forward to trying it out, I'm sure there's a few more sessions to be had from it.

Ray

 

 

 

 

 

Is that fungus on the mirror or front corrector lens, if it’s the mirror, then great care is needed as they are not coated, and very very easy to scratch and ruin the coating... 😮

[m1dlj]

The fungus in the photo is on the primary, the corrector has been removed.

I went at the mirror as carefully as I could, dabbing with distilled water (and one drop of liquid soap), avoiding any sideways motion other than some nervous hand shaking, until I had the fungus and dirt removed, then used IPA and an optical 'wonder cloth'. The surface looks much better, although I accept that I may have degraded the surface slightly. 

I cleaned the corrector in a similar manor to remove what looked like sawdust, without touching the secondary which is in much better condition.

I set it up (between showers) and pointed at the moon, it looked good. The focuser was little stiff at first but worked fine after a bit.

Hopefully we will get to use it at some upcoming pubic event, as long as the Autostar keypad holds up: I don't know if there any replacements still around.

Just a little rust on the outside to deal with now.

[WanderingEye]

1 minute ago, m1dlj said:

The fungus in the photo is on the primary, the corrector has been removed.

I went at the mirror as carefully as I could, dabbing with distilled water (and one drop of liquid soap), avoiding any sideways motion other than some nervous hand shaking, until I had the fungus and dirt removed, then used IPA and an optical 'wonder cloth'. The surface looks much better, although I accept that I may have degraded the surface slightly. 

I cleaned the corrector in a similar manor to remove what looked like sawdust, without touching the secondary which is in much better condition.

I set it up (between showers) and pointed at the moon, it looked good. The focuser was little stiff at first but worked fine after a bit.

Hopefully we will get to use it at some upcoming pubic event, as long as the Autostar keypad holds up: I don't know if there any replacements still around.

Just a little rust on the outside to deal with now.

Well, good job there....

I cleaned my mirror a few years back and was very careful, and still ended up with a small scratch they could only be seen when shining a torch on the mirror, seems ok, just waiting for it to start pealing off or something similar and be ruined... 😮

[lenscap]

13 minutes ago, m1dlj said:

Hopefully we will get to use it at some upcoming pubic event, as long as the Autostar keypad holds up: I don't know if there any replacements still around.

I noticed that ENS have one;

http://ensoptical.co.uk/lx90-handset?search=autostar

No connection. . . .

[Ben the Ignorant]

2 hours ago, m1dlj said:

Q. Does anyone have any experience dealing with fungus like this? What exactly is it, and why grow on the mirror? What else can I do to prevent a recurrence?

First question, yes.

Second question, it's a form of mould (mold in US English), and it grows on optics because they have mineral coatings, a mix of various dust compounds, and condensed water at some moments. Mould survives on extremely small amounts of food and water so, unlucky us, it likes optics. Third question, prevention is keeping optics dry and clean, with an eye on condensation, do not let uncovered cold optics in a warmer room where air humidity can condense. 

Edited October 12, 2019 by Ben the Ignorant

[m1dlj]

7 minutes ago, lenscap said:

I noticed that ENS have one;

http://ensoptical.co.uk/lx90-handset?search=autostar

No connection. . . .

Many thanks, I'll take a look at that.

[m1dlj]

33 minutes ago, Ben the Ignorant said:

First question, yes.

Second question, it's a form of mould (mold in US English), and it grows on optics because they have mineral coatings, a mix of various dust compounds, and condensed water at some moments. Mould survives on extremely small amounts of food and water so, unlucky us, it likes optics. Third question, prevention is keeping optics dry and clean, with an eye on condensation, do not let uncovered cold optics in a warmer room where air humidity can condense. 

Thanks for that Ben. I can't help feeling a bit of a caveman when touching optics: I have a 115mm APO refractor and a few Baader Hyperions which I leave well alone. However, occasionally you just have to give it your best shot. I'm just pleased the mold hasn't etched the surface. 

Edited October 12, 2019 by m1dlj