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Never use a flashlight

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#1 Paradoxdb3

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Posted 22 June 2022 - 05:49 PM

I understood the assignment. Don't get them wet, don't feed after midnight, and NEVER shine a flashlight down the tube. But did I listen? Of course not. And now my OCD is telling me to take the thing apart and clean both the corrector and the mirror.

 

I know LOGICALLY that the mirror is just fine. But my stupid brain keeps telling me to clean, clean, CLEAN! You know what will happen next... I'll end up with a primary that's scratched up. Anyone else struggle with this? Please, not just me.... Lol

 

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#2 John Miele

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Posted 22 June 2022 - 06:14 PM

All I can say is I was exactly like you for years and then somehow gradually I decided not to worry about it. And now, I have gone the other way. You should see the corrector plate on my MN190...you would faint from the shock of it...lol!


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#3 Stellar1

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Posted 22 June 2022 - 06:24 PM

Ask yourself this, was it something wrong with the views that prompted you to shine a light in there? 

 

If the answer is yes

clean it.

 

if the answer is no

DON'T TOUCH IT!! 

 

see! easy peasy, the first image looks perfect but thats just smoke and mirrors, the second is the truth and thats why you'll never get it to look like the first cause that doesn't exist, no such thing as a perfectly clean mirror, the OCD may lead to regrets, my friend.


Edited by Stellar1, 22 June 2022 - 06:29 PM.

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#4 Paradoxdb3

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Posted 22 June 2022 - 06:45 PM

All I can say is I was exactly like you for years and then somehow gradually I decided not to worry about it. And now, I have gone the other way. You should see the corrector plate on my MN190...you would faint from the shock of it...lol!

And in all honesty, unless it's so dirty that it's difficult to see any reflections, it's probably pretty good. I'm only 5 years in, so a baby still... Lol



#5 Paradoxdb3

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Posted 22 June 2022 - 06:48 PM

Ask yourself this, was it something wrong with the views that prompted you to shine a light in there? 

 

If the answer is yes

clean it.

 

if the answer is no

DON'T TOUCH IT!! 

 

see! easy peasy, the first image looks perfect but thats just smoke and mirrors, the second is the truth and thats why you'll never get it to look like the first cause that doesn't exist, no such thing as a perfectly clean mirror, the OCD may lead to regrets, my friend.

Nothing promoted me other than curiosity. I haven't had much of an opportunity to use this yet. It's a used scope, and I don't usually purchase used, for this very reason. Lol and I think you are 100% correct... I can see regrets in my future if I pursue a "cleaning"... "Cleaning" in quotes because it would likely end up in DIRTYING and SCRATCHING. lol


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#6 Jethro7

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Posted 22 June 2022 - 06:54 PM

Hello Paradoxb3.

Plus 1 for "DONT TOUCH IT" doing so may actually cause a real problem.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro


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#7 Stellar1

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Posted 22 June 2022 - 06:57 PM

Nothing promoted me other than curiosity. I haven't had much of an opportunity to use this yet. It's a used scope, and I don't usually purchase used, for this very reason. Lol and I think you are 100% correct... I can see regrets in my future if I pursue a "cleaning"... "Cleaning" in quotes because it would likely end up in DIRTYING and SCRATCHING. lol

Well that’s not necessarily true, I’m sure you can gather up the info needed to successfully clean it up but I would use it and if you’re happy with the views then let it be, if not, or you just want to do it then there are lots of resources for leaning how to do it successfully here on CN. One should not be intimidated by the process, but one should also not look for reasons to do it if the views are good, otherwise we would all be opening our scopes yearly. Cause I can almost bet dollars to donuts the minute you put that corrector back on and shine a light again (and you will) you’ll find that one streak you missed and back to square one.


Edited by Stellar1, 22 June 2022 - 06:59 PM.

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#8 Paradoxdb3

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Posted 22 June 2022 - 07:28 PM

Cause I can almost bet dollars to donuts the minute you put that corrector back on and shine a light again (and you will) you’ll find that one streak you missed and back to square one.

 

BOOM! It's like the human condition, or something. Lol


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#9 Toups

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Posted 22 June 2022 - 08:29 PM

<SNIP> Cause I can almost bet dollars to donuts <SNIP>

<Off Topic>

Always use this expression, except that with inflation it just doesn't have the same meaning.  Originally meant that you would bet a real dollar against something that cost next to nothing.  But now donuts cost about a dollar (or more) depending on where you are.

 

<Back on topic>

Completely agree, like the Hippocratic Oath, first, do no harm.  And also, if it ain't broke, don't fix it.  And the best (or perfect) is the enemy of the good.  I can't count the number of times that I tried to "improve" something that didn't need fixing and the result was worse than what I started with.  So decide carefully if you need/want to "fix" it.


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#10 Cpk133

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Posted 22 June 2022 - 08:59 PM

Buy a new one and keep it in the box.  Only take it out to shine a light inside and admire the pristine optics.  You'll sleep like a baby knowing whatever happens you have a perfectly clean one without so much as a speck.  


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#11 12BH7

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Posted 22 June 2022 - 09:15 PM

Cleaning optics just takes practice. It took me a number of times cleaning my Dob's mirror to learn how to do it right. The only advantage is I didn't have to take the scope apart to learn on.

 

Look at some videos and see what's involved. That should quell those OC desires.

 

I had to clean the inside of my corrector plate. Even with that off I didn't want to dig that deeply into my SCT.


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#12 speedster

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Posted 23 June 2022 - 03:19 AM

My life was perfectly fine until you posted this!  Now, my curiosity tells me to shine a light down mine just to see what's there!


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#13 ABQJeff

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Posted 23 June 2022 - 03:22 AM

I do feel your pain, I have an eyelash from China on the inside of my 9.25's corrector. that is wedged between the corrector and seal that holds the corrector.  I so want to take off the corrector to get it, but you alluded to what would happen: I misalign the corrector putting it back, fingerprints, scratches, it drops onto the primary then I mess up the primary trying to get it out, etc.   My plan is I will take care of it when my corrector plate ever needs cleaning.

 

Look at your scope in indoors room lighting or in daytime inside the garage with the door up.  If you can't see any defects with that lighting, don't touch anything.  That light is already hundreds of times brighter than the dim targets we look at.   A flashlight is just asking for trouble (I know, I cleaned and cleaned my refractor objective once because I stupidly used a flashlight).  Now I use my garage lighting rule.



#14 tturtle

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Posted 23 June 2022 - 09:37 AM

This really gets down to the particulars of why you enjoy this hobby. Me - I don’t really like owning something that I haven’t at least partially taken apart. Taking a telescope apart and understanding how it operates is part of the fun. If you are like minded then get the screwdriver out and go to town.  On the other hand if you are not driven partly by this curiosity then the general consensus here is right, it probably won’t have a noticeable effect on the views. Removing and cleaning the corrector is really easy by the way (the primary mirror is another story). 



#15 12BH7

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Posted 23 June 2022 - 10:25 AM

Just curious, is this your C11?

 

It seems that you've been having some trouble liking this scope all along.  Let me tell you a long endless story about my 8" SCT - only kidding.

 

I bought this 8" SCT about 30 years ago.  For decades I tried using it but it was one crappy scope. I tried collimating it dozens of times - nothing. The moon was fuzzy and planets were even worse. There was also one part of the visual field that on lunar views was ALWAYS out of focus.

 

Fast forward - Turned out the INSIDE of the corrector plate was never cleaned at the factory. And there was a large smudge on the inside of the corrector plate that was causing the out of focus patch. Cleaned the inside of the corrector plate, kept the retention screws more on the lose side, recollimated and holy crap. Now this scope has crisp lunar views.

 

One thing that is not mentioned a lot is that the retention screws holding the corrector plate can be over tightened at the factory. Causing distortion and poor image quality.

 

See if you can track down anyone to help you to properly clean the corrector plate, reset the retention screws and finally get the collimation checked. Most of the time it's not the scope that's causing poor views, it's in need of service and or realignment.


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#16 gnowellsct

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Posted 23 June 2022 - 01:02 PM

I've cleaned SCT mirrors.  I prefer not to, but I have done it.  Greg N


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#17 dweller25

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Posted 23 June 2022 - 01:34 PM

If it aint broke, don’t fix it waytogo.gif


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#18 DSOGabe

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Posted 23 June 2022 - 03:01 PM

Was there something that was affecting your viewing with it?

If not then one needs to remember the very wise words:

    "If it ain't broke, then it don't need fixin' "

 

Start cleaning all the mirrors and windows in the house and car(s) and then repeat at least 3 times. That should satisfy any obsession looking down the tube sparked.


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#19 gnowellsct

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Posted 23 June 2022 - 03:16 PM

Just curious, is this your C11?

 

It seems that you've been having some trouble liking this scope all along.  Let me tell you a long endless story about my 8" SCT - only kidding.

 

I bought this 8" SCT about 30 years ago.  For decades I tried using it but it was one crappy scope. I tried collimating it dozens of times - nothing. The moon was fuzzy and planets were even worse. There was also one part of the visual field that on lunar views was ALWAYS out of focus.

 

Fast forward - Turned out the INSIDE of the corrector plate was never cleaned at the factory. And there was a large smudge on the inside of the corrector plate that was causing the out of focus patch. Cleaned the inside of the corrector plate, kept the retention screws more on the lose side, recollimated and holy crap. Now this scope has crisp lunar views.

 

One thing that is not mentioned a lot is that the retention screws holding the corrector plate can be over tightened at the factory. Causing distortion and poor image quality.

 

See if you can track down anyone to help you to properly clean the corrector plate, reset the retention screws and finally get the collimation checked. Most of the time it's not the scope that's causing poor views, it's in need of service and or realignment.

I have a had a few "stumped me for decades" problems myself.  The internet has greatly helped overcome these obstacles.

 

Once you decide the scope is not worth owning because of whatever impediment it has, that is tremendously empowering for screwing up the courage to take the thing apart and fix it.

 

The result is not always success.  But at least you tried.  And if you kill the scope at least you can pass on to something else.

 

Greg N


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#20 Brent Campbell

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Posted 23 June 2022 - 04:29 PM

I have recently learned that cleaning an SCT is no big deal.   The procedure is roughly as follows:

 

1) Remove corrector

2) Remove Focuser Assembly

3) Remove Corrector Retaining Ring  (basically the lens cell for the corrector)

4) Reach into scope and remove split ring on the spindle that stops the mirror from falling off the spindle

5) Carefully reach in and pull out the mirror

6) clean the scope and put everything back together - installation is reverse of disassembly.  Take the time to regrease the focuser.

 

Two rules I follow.  1) Don't touch or disassemble the secondary.  I understand they are set at the factory.   2) Very hard to remove the mirror from the spindle because they are RTV'd to it.  Also if you do so re-aligning so that the mirror square to the spindle can be a pain.  You can wash the mirror in its spindle with no problem.

 

Here is some references to these procedures:

 

http://ngc1514.com/C...n/disassem.html

https://www.pbase.co...mirror_cleaning

 

(This one is good).

https://astromart.co...sct-childs-play

 

 

Just take it slow and be careful.  You will need to shim the corrector in the same way it was when you took it apart (paper shims).  


Edited by Brent Campbell, 23 June 2022 - 04:31 PM.


#21 LouB

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Posted 23 June 2022 - 09:32 PM

I have cleaned my corrector plate from time to time.  With a sct, I don't think u would ever need to clean the mirror.  Way too much chance of screwing up everything to be worth it.  

I have a 20 yr old 10" Newtonian that needs to be cleaned. But it is effectively open to the elements.  I still haven't tried to clean it. 



#22 Brent Campbell

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Posted 24 June 2022 - 09:14 AM

I have cleaned my corrector plate from time to time.  With a sct, I don't think u would ever need to clean the mirror.  Way too much chance of screwing up everything to be worth it.  

I have a 20 yr old 10" Newtonian that needs to be cleaned. But it is effectively open to the elements.  I still haven't tried to clean it. 

I used to think that way.  The reality is that these scopes are put together on an assembly line.  That means they have to be assembled by someone (fairly quickly) and if they are assembled they can be disassembled.   I was surprised how easy my c8 came apart once I studied the procedures.  
 

The only thing I would not touch is the secondary which is assembled at the factory with a jig and the primary connection to the cell because it is affixed with rtv.  Once you pull the primary it can be washed with the cell like any other mirror.  I forgot to mention that you should regrease the focuser and the spindle.  The hardest part of the whole process was the upper ring that holds the corrector.  This ring tends to get stuck and required a couple taps with a mallet to break it loose after removing all the screws.  You need to get this ring off or the mirror won’t clear the tube.

 

If the sct mentioned earlier were my scope I would disassemble it wash the mirror and reassemble.  The whole process will take about 5 to 6 hours. 



#23 12BH7

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Posted 24 June 2022 - 09:15 AM

I have a had a few "stumped me for decades" problems myself.  The internet has greatly helped overcome these obstacles.

 

Once you decide the scope is not worth owning because of whatever impediment it has, that is tremendously empowering for screwing up the courage to take the thing apart and fix it.

 

The result is not always success.  But at least you tried.  And if you kill the scope at least you can pass on to something else.

 

Greg N

The reason I never saw the problem was because when you check the corrector plate you always end up looking at it on an angle. One day while I was cleaning it, the Arizona sun hit it just right. That was when I saw that the problem was on the inside of the corrector plate.

 

Once I had it off the other optics looked OK so I decided to leave well enough alone. 

 

Also a fellow CN member recommended I keep the CP retention screws only finger tight, as that can cause distortion. Now when I took the CP off the screws holding it on were REALLY tight. I have no proof that this contributed to the problem, but it did confirm that having someone that knows what their doing checking out your scope could turn a dumpster scope into a winner.



#24 Paradoxdb3

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Posted 24 June 2022 - 11:00 AM

If the sct mentioned earlier were my scope I would disassemble it wash the mirror and reassemble. The whole process will take about 5 to 6 hours.


I watched a video of someone cleaning their 14" with the primary in place, and just reaching inside. If I DO clean it, that's what I'll do. It's an older scope, but it focuses like a dream. Almost zero mirror shift, and when I checked collimation and mirror flop, I saw some evidence at first, but after tightening the retaining ring on the primary, it appears to be gone. More time is needed on this scope.

I'll also use a vacuum wand with a brush attachment to get rid of any dust debris inside the tube (not on the mirror), and a new garbage bag over the front of the scope while the corrector is off, to keep new dust from collecting. I've got plans... How they play out? Welllllll...... Lol

#25 12BH7

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Posted 24 June 2022 - 11:10 AM

I watched a video of someone cleaning their 14" with the primary in place, and just reaching inside. If I DO clean it, that's what I'll do. It's an older scope, but it focuses like a dream. Almost zero mirror shift, and when I checked collimation and mirror flop, I saw some evidence at first, but after tightening the retaining ring on the primary, it appears to be gone. More time is needed on this scope.

I'll also use a vacuum wand with a brush attachment to get rid of any dust debris inside the tube (not on the mirror), and a new garbage bag over the front of the scope while the corrector is off, to keep new dust from collecting. I've got plans... How they play out? Welllllll...... Lol

Hey, best of luck. It seems that there is an issue with your scope. If you're not enjoying using it then what do you have to lose.




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