I suspect I have a telescope disaster!

[Gina]

Not having done any astro imaging for a couple of years and even longer with my SW MN190 Mak-Newt, I thought I would try using it to observe Jupiter.  It's been in my observatory and has suffered some sort of damage - something nasty on the inside of the meniscus lens.  Whether this can be cured or even made a bit better I have no idea.  Here are 3 photos of the scope mounted on my EQ8 in the observatory.  Firstly, one at an angle reflecting clouds, next is almost straight on and finally, through the focuser tube, reflected by the secondary and focused on the meniscus lens.  Stretched enormously in GIMP to show the problem.  I'm gutted - this was a nice scope!!

Edited July 1, 2019 by Gina

[paul mc c]

Nightmare......it looks bad,hopefully it will clean for you,hope so,i have never owned one of those scopes so dont know if it can be opened.

[Gina]

I'm hoping it can, though it occurs to me that I might be able to remove the focuser and get in that way.  I shall need to take the focuser apart again as it needs adjusting.  I bought the scope second hand with a non-working focuser and I refurbished it so I can do the same again.  It's probably adequate for an eyepiece but won't hold a camera and EFW.

[Stu]

Eeeek, that doesn't look great. I think the coatings on these corrector plates are fairly robust but I guess it depends what it is. I assume it is internal?

[Freddie]

Looks like it is time to take the corrector off and give it a clean. I took mine off to fit a Moonlite, it’s not particularly tricky to do.

[Gina]

2 minutes ago, Stu said:

Eeeek, that doesn't look great. I think the coatings on these corrector plates are fairly robust but I guess it depends what it is. I assume it is internal?

Yes, it's on the inside, whatever it is.  The outside is fine.

[Gina]

2 minutes ago, Freddie said:

Looks like it is time to take the corrector off and give it a clean. I took mine off to fit a Moonlite, it’s not particularly tricky to do.

Oh that's something.  Good - thank you.

[Stu]

Just now, Gina said:

Yes, it's on the inside, whatever it is.  The outside is fine.

I guess I would remove the front plate and see what can be done then. I dis recover a C925 corrector plate which had extensive snail trails over it and various other muck. Worked fine afterwards.

It is a strange looking effect though, doesn't look fungal but guess it must be?

[Gina]

No, I doesn't look fungal to me either.  More like the coating has separated!!    I'm nearly in tears!

I'm not going to try taking it apart tonight but might attack it tomorrow.

Edited July 1, 2019 by Gina

[Stu]

3 minutes ago, Gina said:

No, I doesn't look fungal to me either.  More like the coating has separated!!    I'm nearly in tears!

I'm not going to try taking it apart tonight but might attack it tomorrow.

Oh bless you. Try not to worry until you manage to get a proper look at it. Very frustrating. Is it in a damp environment, I assume not?

[Gina]

Been in the observatory which I have endeavoured to keep dry but judging by the rust on the EQ8 I haven't done very well.

[DougM43]

Oh no,, hopefully it’s not as bad as it looks and cleans off fairly easily when you get it apart.

[Alan White]

Very sorry to read this Gina.

Having had some fungus on old camera kit that had gotten damp,
it does have a slight fungal look to it to me.

I would split the scope open and have a careful clean.
Gentle wash over with soapy clean and warm water, followed by Baader Wonder Fluid perhaps.

I would not fret too much until you have had a closer look and tried a careful clean.

Good luck with this Gina, fingers crossed for you 🤞


 

[JamesF]

Could just be stains from water that has condensed out on the inside of the lens at some point.

I had something similar on my C9.25 when I got it out of storage to go into the observatory a month or so back.  It looked horrible, but cleaned up without any obvious damage to the lens itself.

James

[StarDodger]

7 minutes ago, Gina said:

Been in the observatory which I have endeavoured to keep dry but judging by the rust on the EQ8 I haven't done very well.

I wouldn’t go by the bolts on the EQ8 they are rubbish and will rust even in perfectly dry conditions...I have just replaced all mine for a full set of stainless steel ones, and looks so much better, I hope you get that scope sorted though, I think you will as you seem to be a woman of many talents...

[Gina]

3 minutes ago, JamesF said:

Could just be stains from water that has condensed out on the inside of the lens at some point.

I had something similar on my C9.25 when I got it out of storage to go into the observatory a month or so back.  It looked horrible, but cleaned up without any obvious damage to the lens itself.

James

I see - that sounds promising.  Thank you.

Edited July 1, 2019 by Gina

[Markkus]

Some rather long winded advice on cleaning a similar scope here.  I haven't tried it myself!

[Gina]

1 minute ago, StarDodger said:

I wouldn’t go by the bolts on the EQ8 they are rubbish and will rust even in perfectly dry conditions...I have just replaced all mine for a full set of stainless steel ones, and looks so much better, I hope you get that scope sorted though, I think you will as you seem to be a woman of many talents...

Ah yes, replacing the EQ8 bolts sounds a good idea.

[StarDodger]

Just now, Gina said:

Ah yes, replacing the EQ8 bolts sounds a good idea.

I Have a full list of them if you need..

[sloz1664]

Hi Gina,

Sorry for your dilemma, but not get too worried, the lens coatings are robust. Just remember, on removal, to mark the edge of the corrector plate and the corresponding edge of the telescope tube, as the alignment is critical. 

Everything crossed...

Steve

Edited July 1, 2019 by sloz1664

[Gina]

There are two sets of screws that may take it apart - 6 dome head cross-head screws between scope main tube and corrector holder and 6 countersunk cross-head screws in the front flange.  I guess the dome head screws would be the ones to remove but I need confirmation.

[Highburymark]

Am wondering if there's anyone who services these scopes who could help? Used to see ads in the astro magazines but haven't seen them for a while

[JamesF]

16 minutes ago, Gina said:

There are two sets of screws that may take it apart - 6 dome head cross-head screws between scope main tube and corrector holder and 6 countersunk cross-head screws in the front flange.  I guess the dome head screws would be the ones to remove but I need confirmation.

If it's like the SCTs, the screws on the front hold a retaining ring that allows the corrector lens to be removed.  The screws in the sides hold the corrector lens cell in place.

Regarding alignment, once I'd taken the retaining ring and the gasket off my SCT I put a piece of tape across the edge of the lens where it wouldn't be seen if any residue were left when I removed it and continued over the end of the tube, then cut through it with a craft knife where the lens and tube meet.  Makes alignment on reassembly a doddle, though I'd guess it is a little more demanding with the Mak Newt.

James

[Freddie]

30 minutes ago, Gina said:

There are two sets of screws that may take it apart - 6 dome head cross-head screws between scope main tube and corrector holder and 6 countersunk cross-head screws in the front flange.  I guess the dome head screws would be the ones to remove but I need confirmation.

Undo the 6 around the scope tube and remove the corrector plate/cell in one piece.

[JamesF]

8 minutes ago, Freddie said:

Undo the 6 around the scope tube and remove the corrector plate/cell in one piece.

It's possible they actually have nuts on the back, though as you have a MN190 by the looks of it, perhaps you have already done this and know there aren't?

James