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Daveyboy

Cleaning secondary mirror

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Hi all , just been watching some videos on how to clean a mirror on my telescope .

The reason I need to clean my secondary is because as I was collimating I clumsily put my fingers all over my secondary mirror as I was lining it up with the eye priece .

The question is ..... Is r/o water the same as distilled ?

I ask this as I'm also a keeper of marine fish and have plenty of r/o . Or does it have to be distilled ?

Many thanks Dave

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It's not quite Dave but I got 5litres of distilled in a chemist for a couple of euros. So why take the chance?

Be careful, don't rush, be gentle, really gentle, don't force anything, you get the idea!

Good luck

I should say it should be very dirty before it affects the view. Had you eaten a jam sandwich messily before tackling the secondary previously??:)

Barry

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Hi Dave not sure what r/o water is but most water types are treated to remove ions, minerals etc distilled water is just that pure water and is much more expensive to produce some military hardware manufacturing processes even require double distilled or better to ensure there are no impurities.

For optics i would stick to distilled if you can get it.

Alan

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Thanks for the replays guys . Thought I had better check befor using it . Cheers and beers Dave

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I tried to get hold of distilled water to clean my secondary at six different

It's not quite Dave but I got 5litres of distilled in a chemist for a couple of euros.

Barry

Must be the luck of the Irish, Barry!  :smiley:  I tried to buy distilled water to clean my secondary at six different chemists in my area with no joy... luck of the Welsh I guess!  :sad:  Ended up using deionised water, which seems to have worked ok. I carefully rinsed the secondary under a warm water tap first, then poured some jugged warm water with a drop of fairy liquid onto it, and rinsed with deionised. Was going to use surgical cotton wool to swab the secondary, but didn't need to as the above process did the trick.

I remember cleaning my primary back in the 1970's and got some distilled water at my first port of call - the village chemist!...ah, those were the days those were!  :grin:

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Oh dear, I hope I haven't done something very stupid!

When viewing Jupiter last week with my 200p Dob I noticed that with my 7mm and 5mm EPs I could see semi-transparent segmented filaments that looked like bacteria through a microscope. I assumed this was dust or some other sort of contamination on the secondary so I gave it a gentle wipe with my spectacle cleaning cloth. The filaments are no longer there so it seems my assumption was correct, but have I damaged my secondard by doing this?

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Oh dear, I hope I haven't done something very stupid!

When viewing Jupiter last week with my 200p Dob I noticed that with my 7mm and 5mm EPs I could see semi-transparent segmented filaments that looked like bacteria through a microscope. I assumed this was dust or some other sort of contamination on the secondary so I gave it a gentle wipe with my spectacle cleaning cloth. The filaments are no longer there so it seems my assumption was correct, but have I damaged my secondard by doing this?

If you can see dirt or whatever when viewing, it will be at or very close to the focal plane, so within the eyepiece.  Stuff on the secondary mirror won't be seen through the eyepiece.

Have a look at the secondary, looking through the focuser with no eyepiece fitted.  If it looks ok, I wouldn't worry. Although it does break the rules, I've VERY carefully cleaned a Newtonian secondary using a microfibre cloth and isopropyl alcohol.  Years later, the secondary looked fine.  But I don't do it that way now, careful wash gets it done.

Regards, Ed.

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One bit of advice when you're cleaning a secondary mirror is to keep water out of the mounting metalwork and the screw thread. As recommended by Steppenwolf, I wrap the metal column in two layers of cling film secured with an elastic band before using warm water and a drop of detergent and then fresh tap water followed by distilled water rinses.

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One bit of advice when you're cleaning a secondary mirror is to keep water out of the mounting metalwork and the screw thread. As recommended by Steppenwolf, I wrap the metal column in two layers of cling film secured with an elastic band before using warm water and a drop of detergent and then fresh tap water followed by distilled water rinses.

Yes, I should have mentioned this in my post.  I didn't use cling film, which is a good idea, but was very careful not to keep water out of the metalwork.

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Oh dear, I hope I haven't done something very stupid!

When viewing Jupiter last week with my 200p Dob I noticed that with my 7mm and 5mm EPs I could see semi-transparent segmented filaments that looked like bacteria through a microscope. I assumed this was dust or some other sort of contamination on the secondary so I gave it a gentle wipe with my spectacle cleaning cloth. The filaments are no longer there so it seems my assumption was correct, but have I damaged my secondard by doing this?

It is possible what you saw was cells floating around in your eye. I see them quite often on bright targets at high power if my eye isn't at the focal point.

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It is possible what you saw was cells floating around in your eye. I see them quite often on bright targets at high power if my eye isn't at the focal point.

I sometimes see them during a sunny day as well , 

Floaters.png

File:Floaters.pngFile:Floaters.png

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I sometimes see them during a sunny day as well , 

Floaters.png

File:Floaters.pngFile:Floaters.png

That's them!

Are those on the surface of the eye or floating around inside?

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They are floating around inside. <br />

<br />

<br />

Sent from my GT-N7105 using Tapatalk<br />

<br />

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Thinking of having a crack at cleaning the primary mirror later (probably a very poor choice of word). Covered in dust and rubbish.

We spend loads on eyepieces and dither about using Barlows because we would be putting an extra piece of pristine glass in the light path. But, at the same time, seem happy to use mirrors that look like someone has eaten their lunch off them. Doesn't make sense.

I did the secondary before Christmas using a clean sink of tepid water with a dash of washing up liquid. If you keep the mirror submerged and brush lightly with a cotton wool ball under water the cleaning process is exceptionally gentle. A good rinse and using the corner of some kitchen towel to break the surface tension on an upright mirror resulted in the water just running off and a dry mirror with no residue.

Worked a treat. Just got to do it with a 10" mirror now......

Wish me luck.

Paul

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We spend loads on eyepieces and dither about using Barlows because we would be putting an extra piece of pristine glass in the light path. But, at the same time, seem happy to use mirrors that look like someone has eaten their lunch off them. Doesn't make sense.

It has to do with where the focal plane is. Dirt on the primary is well off the focal plane, so isn't seen. In comparison, barlows are very near the focal plane and dirt on them can bee seen.

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Thinking of having a crack at cleaning the primary mirror later (probably a very poor choice of word). Covered in dust and rubbish.

We spend loads on eyepieces and dither about using Barlows because we would be putting an extra piece of pristine glass in the light path. But, at the same time, seem happy to use mirrors that look like someone has eaten their lunch off them. Doesn't make sense.

I did the secondary before Christmas using a clean sink of tepid water with a dash of washing up liquid. If you keep the mirror submerged and brush lightly with a cotton wool ball under water the cleaning process is exceptionally gentle. A good rinse and using the corner of some kitchen towel to break the surface tension on an upright mirror resulted in the water just running off and a dry mirror with no residue.

Worked a treat. Just got to do it with a 10" mirror now......

Wish me luck.

Paul

Be careful on the cotton wool you use - even some of the "pure" cotton wool contains man made fibres which are harsh enough to scratch your mirror coatings.

It's surprising how dirty mirrors can get before it has a noticeable effect on views - even with premium eyepieces.

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Can you show us an image of the dirty primary mirror, because I've noticed a bit of dust on mine and not sure when do I need to start cleaning and how to as well. I just want to ignore cleaning it until I'm sure I can do it right. I'll get a picture of the primary later on. 

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Can you show us an image of the dirty primary mirror, because I've noticed a bit of dust on mine and not sure when do I need to start cleaning and how to as well. I just want to ignore cleaning it until I'm sure I can do it right. I'll get a picture of the primary later on. 

post-5361-0-62349500-1349738469.jpg

The mirror at Kielder

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Unless that is condensation on the Keilder mirror I think I would want to give it a wash. :eek:

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Maybe mine isn't so bad then.

I have just had a really good look at it for the first time. I shone a desk lamp onto the back of the mirror (in situ) and noticed that there are lots of little pin [removed word] holes in the coating (quite pretty to look at - like a little 10" sparsely populated planetarium).

I am also thinking that any cleaning that I do, no matter how careful I am, would risk peeling off chunks of coating. So I think that I'll hold fire on the cleaning front until a jam sandwich gets dropped in it (3 small children - it is going to happen).

The scope is less than a year old (if the chap that I brought it from is to be believed). Is this normal?

Paul

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Hello!

I'm a fellow reefer too.

The R/O water stands for reverse osmosis water. It is as safe as distilled water or deionized water.

The three processes strips the ions of the water using diferent methods:

Distiled: evaporation of the water, leaving the salts behind;

Deionized: A adsorption resin exchanges the salts for H and OH (just more water, roughly speaking)

Reverse Osmosis: A semi-permeable membrane lets pass only the H2O molecules (think of it like a molecular sieve).

Cheers

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