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When to clean my mirror?

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#1 Metalmanstan

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Posted 16 November 2012 - 06:21 AM

I went out to observe with my friend last night and it was a beautiful night. My buddy had a spot light that he was checking for coyotes from time to time so we wouldn't get eatin :shocked: He took the light and shined it down the tube and he said it looked dirty. I looked down it and saw that there was a 'viewable' amount of dust/specs on it. I was wondering if it was time to clean the mirror or when I know it is time to clean it? I can try to take a picture and post it if you need me to. Thanks!! :rockon:

#2 frito

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Posted 16 November 2012 - 07:44 AM

shining a flashlight onto a mirror in the dark will make it appear much worse than it probably is a small to moderate amount of light dust will have little to no impact on the mirrors performance and it would be better to carefully remove the mirror cell and take a photo of it/inspect it if you want to look into it further.

#3 gpelf

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Posted 16 November 2012 - 08:50 AM

+1 on the light down the tube, This will always make a mirror look bad even 5 min. after cleaning it. Just look down the tube in daytime with ambient light.

#4 uniondrone

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Posted 16 November 2012 - 10:21 AM


As others have said, using a flashlight will make any mirror look absurdly filthy. It actually takes a lot of dust to appreciably affect the view. I would say that the best course of action is to do your best to prevent it from getting dirty in the first place, but don't be paranoid about it. Then perhaps once every year or two give it a clean like suggested here: Mirror Cleaning

#5 Don Trinko

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Posted 16 November 2012 - 11:23 AM

As above. It takes a lot of dust and dirt to effect the view.
It is best to not look or you will convince yourself that it needs cleaning. All IMO; Don T.

#6 howard929

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Posted 16 November 2012 - 11:58 AM

+1.

After just a few months of use the primary in my Z8 looked terrible with a flashlight inspection. I handled that problem with quick peeks during collimation and by not doing that again.

#7 faltered

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Posted 16 November 2012 - 12:20 PM

it takes a lot to effect any view. Leave it alone, you can easily do more damage than good by cleaning. I have looked out of large dobs with mirrors that are FILTHY and the view is still amazing.

#8 Tim2723

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Posted 16 November 2012 - 04:06 PM

Never ever shine a flashlight down the tube. It will only cause you undue concern. With few exceptions, cleaning the mirror represents a far greater risk than just leaving it alone. In almost every case, had one not seen the dust with the light, it would have gone unnoticed for a long time.

#9 Metalmanstan

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Posted 19 November 2012 - 08:18 PM

Alright, so I was just out for a little bit looking at the moon and it looked pretty good. I happen to look down the tube and I can still see a good amount of dust and speckles on the mirror. Is it time to clean it or since the views are good just leave it alone?

#10 JohnMurphyRN

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Posted 19 November 2012 - 08:43 PM

I'd leave it alone...Cleaning it is not a benign process. If the view is fine why risk damaging it?

#11 drewp

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Posted 19 November 2012 - 09:10 PM

the risk reward ratio for you to clean or not to clean is very heavily weighted to not cleaning the mirror. you probubly will never see the difference at the ep and risk damaging delicate coatings on the mirror by cleaning. best bet is to stop shining flashlights down the scope tube and forget you saw it in the first place. lol

#12 Metalmanstan

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Posted 19 November 2012 - 09:18 PM

Drewp - sorry buddy, tonight I didn't use a flash light, it was just light from the moon. :p

#13 GOLGO13

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Posted 19 November 2012 - 10:53 PM

My opinion is once every year or two...depending on how much you are using the scope. Certainly if it's really getting grimy it can affect the view. If a bird poops on it or some kind of bug stuff gets on there it should be cleaned right away.

As to how to clean it, that's tricky. Lots of opinions on that which conflict with each other.

#14 GeneT

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Posted 19 November 2012 - 11:16 PM

There are times to clean a mirror. Bird droppings,tree sap,and other similar items should be cleaned immediately. Dust should pretty much be left alone. I subscribe to the general theory that more damage is done by over cleaning than too little.

#15 TexasRed

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Posted 20 November 2012 - 05:36 AM

Only clean mirrors that really need it. A layer of dust does not need cleaning. An extensive collection of dead insects, on the other hand...

#16 uniondrone

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Posted 20 November 2012 - 10:07 AM

My opinion is once every year or two...depending on how much you are using the scope. Certainly if it's really getting grimy it can affect the view. If a bird poops on it or some kind of bug stuff gets on there it should be cleaned right away.


I agree. The key is not to be overly concerned with the normal amount of dust that comes with normal use. At the same time, don't be afraid to clean it once a year or so, or as needed, provided that you use caution. The biggest danger in cleaning a mirror is actually dropping it or chipping it. Scratching the reflective surface can happen, but only if you are dragging something abrasive across the surface.

#17 dpwoos

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Posted 20 November 2012 - 12:14 PM

I vote for never cleaning, and then after many years finally giving in to the temptation. Maybe if I lived in a dust cloud I would think differently, but here in Vermont I am going on eight years and am starting to think about spritzing the mirror with distilled water. So far, the performance of the mirror has never disappointed. And I observe a lot.

#18 Metalmanstan

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Posted 20 November 2012 - 02:43 PM

Well I bought the telescope used and he had it for about 5years. I don't think he cleaned it during that time span. Just wanted the pros opinions of if I should or shouldn't.






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