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Dew when bringing scope in


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Always let my Newtonian mirrors dry naturally with the cap off. Last night when i came in with the stella lyra 8 CC the primary was heavily dewed. So just let it dry with the cap off. However this morning its left a milky film over the primary. That is not drying off.

Should i be concerned about this ? Should i have used a blow dryer down the tube. Would this have prevented this ?

I dont like blow drying the primary mirror. As it can blow dust onto it. Catch 22  Anyway peoples thoughts appreciated

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Update here is some images of the problem The torch makes it look worse than it is. Still its annoying. To clarify it wasnt a new scope but ex dem not from Flo. But it just had some dust and a few dew spots where they tested it a couple of times. But after i got the scope in last night, in a unheated house. It really dewed up quite thickly, left the cap off. But a slight misty ring has appeared, and the mirror is a little bit mistier than it was.  When it does come time to clean the optics. Orion usa say send the telescope to them. What happens with this as far as cleaning the primary goes does anyone know ? Has anyone seen anything like this. Should i be concerened, will it affect performance. My guess is it wont. Opinions welcome guys. You can see the results of first light on the lunar section. 

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Edited by neil phillips
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I leave mine in an unheated conservatory for a couple of hours then put the cap on. That mirror doesn't look that clean. Looks a bit like someone has tried to clean the mirror. 🤔

Here’s mine after two years and never been cleaned. It’s actually easy to take the back off the scope with the primary mirror by simple removing the little screws around the rear of the tube.

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Edited by johninderby
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6 minutes ago, johninderby said:

I leave mine in an unheated conservatory for a couple of hours then put the cap on. That mirror doesn't look that clean. Looks a bit like someone has tried to clean the mirror. 🤔

Here’s mine after two years and never been cleaned. It’s actually easy to take the back off the scope with the primary mirror by simple removing the little screws around the rear of the tube.

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I agree it doesnt look that clean. But i dont think its been cleaned. So you think its a doable job to clean these primarys. The orion manual tells you not too

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8 minutes ago, johninderby said:

See no reason why you can’t clean the mirror. Specs say it has a dielectric coating so mirror surface is protected  Would remove the back though to give you proper access.

Wonder what is the best way to go about that, Ive cleaned newtonians. but this has a baffle ?

Edited by neil phillips
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I had a misty residue that persisted even after drying after one night. Like yours it was not really visible unless i tried to look for it with a light, but it was there. I think in my case it was because my newtonian was right next to my car, which was running and had an auxiliary heater running (diesel powered, lots of particulates in exhaust). By right next to the car i mean i had my mount powered from my center console 12V DC cigarette lighter with a cable through a gap in a slightly open passenger side door. Also, the auxiliary heater is on the passenger side and can shoot exhaust pretty much directly in the OTA given the right wind direction. Im pretty sure some water vapour or exhaust residue got into the mirror surface from the open back of my tube and left something on the mirror surface. Cleaned it properly and haven't seen it since, so cant be sure but i think that was the cause. For what its worth i used it for months after noticing it and did nothing about it, so i don't think it affects performance.

Now how some residue from some gas or liquid gets itself into the closed back tube of your CC i don't know. Perhaps the previous owner had it stored vertically and something dripped on to the mirror? If you look at the mist ring it sort of looks like its directly under the secondary when the tube is vertical.

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21 minutes ago, johninderby said:

With the back removed believe you can unscrew the baffle. If you read the Baader Optical Wonder cleaning instructions it tells you how to clean mirrors. 

https://www.baader-planetarium.com/en/downloads/dl/file/id/110/product/1661/cleaning_and_maintenance_of_optics_a_short_instruction_guide.pdf

 

Think it would be safer to use water with a finale rinse of distilled. Not cleaning yet. its not dirty enough for that yet. Though the slight misting and misty ring is annoying. i have seen similar tarnishing on my newtonian after heavy dewing. But not with a central ring. Which is the weirdest thing 

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5 minutes ago, ONIKKINEN said:

I had a misty residue that persisted even after drying after one night. Like yours it was not really visible unless i tried to look for it with a light, but it was there. I think in my case it was because my newtonian was right next to my car, which was running and had an auxiliary heater running (diesel powered, lots of particulates in exhaust). By right next to the car i mean i had my mount powered from my center console 12V DC cigarette lighter with a cable through a gap in a slightly open passenger side door. Also, the auxiliary heater is on the passenger side and can shoot exhaust pretty much directly in the OTA given the right wind direction. Im pretty sure some water vapour or exhaust residue got into the mirror surface from the open back of my tube and left something on the mirror surface. Cleaned it properly and haven't seen it since, so cant be sure but i think that was the cause. For what its worth i used it for months after noticing it and did nothing about it, so i don't think it affects performance.

Now how some residue from some gas or liquid gets itself into the closed back tube of your CC i don't know. Perhaps the previous owner had it stored vertically and something dripped on to the mirror? If you look at the mist ring it sort of looks like its directly under the secondary when the tube is vertical.

Yes it does doesnt it like its related to the baffle or something. When i got the scope and opened the  box i could see fogging as it does when you didnt let the scope acclimatize. I could see the ring then. But when it warmed up it disappeared. But after the heavy dewing its now stayed put. I might just wait untill it gets real dirty before cleaning.  its a mystery.

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Obsession telescopes has a video on YouTube about how to clean mirrors. I’m not sure if I’m allowed to post a link, but if you google it , it’s there. 
I also get dew when moving my stuff in. I also just let it dry overnight. I think a cap helps prevent dust settle on the wet surface .

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13 minutes ago, TBRHussaR said:

Obsession telescopes has a video on YouTube about how to clean mirrors. I’m not sure if I’m allowed to post a link, but if you google it , it’s there. 
I also get dew when moving my stuff in. I also just let it dry overnight. I think a cap helps prevent dust settle on the wet surface .

Like this?

https://youtu.be/tQrkJubzyP0

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  • 2 months later...
On 20/11/2021 at 13:28, neil phillips said:

Always let my Newtonian mirrors dry naturally with the cap off. Last night when i came in with the stella lyra 8 CC the primary was heavily dewed. So just let it dry with the cap off. However this morning its left a milky film over the primary. That is not drying off.

Should i be concerned about this ? Should i have used a blow dryer down the tube. Would this have prevented this ?

I dont like blow drying the primary mirror. As it can blow dust onto it. Catch 22  Anyway peoples thoughts appreciated

 Very odd. More annoying than anything, as you say probably won’t affect the viewing significantly, but you’ll just know about it’s there. Also, I find that any kind of dirty film on the mirror will make it more prone to dewing, so that is another good reason to clean. If it was just dust I wouldn’t bother. I’d be inclined to give it a gentle wash with something that can remove dirty film, but that’s just me. 

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2 hours ago, RobertI said:

 Very odd. More annoying than anything, as you say probably won’t affect the viewing significantly, but you’ll just know about it’s there. Also, I find that any kind of dirty film on the mirror will make it more prone to dewing, so that is another good reason to clean. If it was just dust I wouldn’t bother. I’d be inclined to give it a gentle wash with something that can remove dirty film, but that’s just me. 

These mirrors will all need cleaning at some point. Best bet is to wait until they are very dirty. Not even close to that point yet. I get your point. But until it looks awful. its not worth it. The mirrors are hard to clean in the traditional way. So again you dont want to be doing it that much, I  think. On a plus side this set appears to be superb. And is performing very well. When they truly need it

It will look pretty bad by then. And i may send it off to Orion UK possibly ? the reflection with torch makes it look worse than it actually is

Edited by neil phillips
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When I bring scopes indoors I have them capped when they come in and I then take the caps off once they have warmed up a bit. This usually prevents mirrors/lenses from dewing up at all when coming back indoors. I find that as soon as any surface dews up it quite effectively sticks any dust or other stull onto the surface even after the surface has dried off so I do everything I can to avoid it.

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20 minutes ago, neil phillips said:

These mirrors will all need cleaning at some point. Best bet is to wait until they are very dirty. Not even close to that point yet. I get your point. But until it looks awful. its not worth it. The mirrors are hard to clean in the traditional way. So again you dont want to be doing it that much, I  think. On a plus side this set appears to be superb. And is performing very well. When truly need it

It will look pretty bad by then. And i may send it off to Orion UK possibly ?

It’s never a bad policy to “leave well alone”, especially if you’re perfectly happy with how it is performing.  🙂 I guess part of my reason for suggesting the clean was that I have had an RC6 for many years (different to yours I know) and the primary has never dewed up, even when everything else has, so I’m wondering whether your dewing indicates a film on the mirror.  My SCT corrector plate was much less prone to dew after I cleaned it, but that was 10 years worth of gunk I removed, so a bit different to your situation! Of course, none of this explains the misty ring after dewing. 

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54 minutes ago, Paz said:

When I bring scopes indoors I have them capped when they come in and I then take the caps off once they have warmed up a bit. This usually prevents mirrors/lenses from dewing up at all when coming back indoors. I find that as soon as any surface dews up it quite effectively sticks any dust or other stull onto the surface even after the surface has dried off so I do everything I can to avoid it.

I do the same. But for some reason all my scopes once cap is off. Will briefly dew over. Even the refractors. I keep the heating off when doing this. But is still warm perhaps from when it was on earlier

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1 hour ago, RobertI said:

It’s never a bad policy to “leave well alone”, especially if you’re perfectly happy with how it is performing.  🙂 I guess part of my reason for suggesting the clean was that I have had an RC6 for many years (different to yours I know) and the primary has never dewed up, even when everything else has, so I’m wondering whether your dewing indicates a film on the mirror.  My SCT corrector plate was much less prone to dew after I cleaned it, but that was 10 years worth of gunk I removed, so a bit different to your situation! Of course, none of this explains the misty ring after dewing. 

As above Rob. Nothing unusual i dont think. My Newtonian does the same. Fracs too. But there could still be a slight film around the baffle. Infact looking now. it looks less there than it used to be. But the mirrors generally getting dirtier because i am using them a lot. But does actually appear to have improved i think. Weird as it seems

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Edited by neil phillips
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Which opens a whole other topic the flashlight test. And possibly why in many cases we shouldnt use it. Especially if it leads to over cleaning and even more damage to the coatings. 

On the photos above there is a couple that look great. and some that look bad. But in comparison. The flashlight does exaggerate every speck of dust. every dew spot. sleek. Ect. It makes us obsessive to the point. of irrational performance worries. I feel. When i was younger i was very much like that. But years of the flashlight test have knocked that out of me. Now i use the scopes, use it some more. Keep using it untill performance is getting less. At this stage the flashlight test looks awful, and its time to clean. This set here is still fairly new. Despite the fact they are a little dirty. Come back this time next year. and we will see how bad they look. And how many great images of the moon and planets i have taken in that time. Puts it all into perspective. Pristine optics, are probably not getting used as much as mine. I would wager. 

Edited by neil phillips
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On 24/11/2021 at 19:36, Ian McCallum said:

Fine up until he starts wiping with the tissue. Too vigorous. No need to wipe that fast. Take your time with light strokes. Its not a competition to see how fast it can be done. Ive had sleeks  with far lighter and slower cleaning.

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