How to strip and clean the optics of a SCT (Schmidt-Cassegrain Telescope)
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- เผยแพร่เมื่อ 13 ก.พ. 2017
- This video gives step-by-step instructions on how to safely remove the Schmidt-plate (corrector) from a SCT. It then continuous to show the proper method of cleaning the Schmidt-plate as well as the primary mirror, in-situ. After assembly, the collimation was also done. Although SCTs are quite similar, the specific telescopes shown here are a 16-inch Meade LX200 and a 14-inch Celestron.
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Hello! I hope this message finds you well. I thank you for this video. I came upon a Meade 14" LX200 GPS whose optics were in good condition, just dusty and a bit of mold forming. The courage it takes to break down a scope is nothing to scoff at. The ONLY reason I successfully cleaned and returned my scope to full and pristine operation was via your video. Thank you many times over and over again.
Nice job. When I worked at Meade we used tissue to clean the optics. We used alcohol or water to clean. We didn't use soap but your optics were pretty dirty. Our Vice president in charge of production would bring tours through and hold a dust cover over half the lens and have someone look through the eye piece to show that you could still see objects. He did this so people didn't get freaked out that the lens was dirty and that it had to be super clean to use. The glass on this scope was very dirty and you did an awesome job. Scratching the coating can happen no matter how careful you are but most of the time you will be OK as long as you do what you did and remove the big dirt particles. Your collimation shouldn't change as long as you put a witness mark on the lens like you did. I haven't worked at Meade since '06 and this brought back memories some good and some nightmares. You would be surprise at some of the scopes that came back for repair.
Always great to hear from someone with first hand experience with the equipment manufacturing process. I'm returning my 25 year old 10" LX 50 into service after many dormant years. I've never cleaned the optics up to this point. Unfortunately there seems to be a couple of patches on the corrector plate which I assume to be some sort of organic growth. I used a very soft brush on it and it smeared so it doesn't look to be too ingrained in the plate. Now I trying to decide whether to clean using Dr. Clays ASO method or go full out and get first contact polymer instead. The cost of the latter is significant however and even more so when international shipping and import duties are added on top.
Would you happen to know anything about how to change my location on the telescope
Was it isopropyl alcohol or ethyl alcohol?
@@ulisessolis3182 we used isopropyl alcohol
@@bryanhuehnken7171 thanks for your answer. Just one more question, could the ethyl alcohol damage the lenses if it's used for cleaning?
I haven't cleaned my celestron c7 since new in the earlier 90s but watching this has enthused me to have a go, thanks.
I have never been so scared and so satisfied at the same time.
Thanks so much for this video. I have an old Meade 10" LX200 I was cleaning up to give to my grandson. Looking at it I could see cobwebs inside so yes, it was in definite need of some crucial cleaning. Your video made it very clear the steps I needed to perform in order to clean it up properly. Without your video I know I would have done the work incorrectly and probably broke or messed up the OTA. Going to clean it up this week and I'm sure it will go smoothly now that I know what I need to do.
Outstanding demonstration of cleaning. I followed these instructions and recovered my Celestron CS8. Thank you!!!
Thank you so much. It warms my heart to see a seasoned craftsman at work. Reading how people do and do not clean on these forums/videos etc etc just makes me not even want to attempt it your self. You, on the other hand tell us what to do/not to do while doing it. Clip is sped up i couldn't ask for a better demonstration thank you sir.
Thanks for the great feedback, glad you enjoyed my video. Good to hear you considered me a "seasoned craftsman", but I must confess, this was only my second time doing a SCT, although I have been around optics for some time. I learned the theory of what to do from our optical people at the observatory, which gave me confidence what to do. My "reward" was a comment from an ex-Meade employee which confirmed that I got it right, dispite other "experts" being quite critical as you can see from the comments. Good luck with your cleaning attempt, its not that difficult.
@@SterremanWillie Yes sir you showed me exactly what i needed to see. Well your confidence and demonstration was all i needed, you're a natural then with (SCT). Thanks again!!!
Watching you clean your telescope with that much love transport me back to the time when I used to change my babies diapers.
THANK YOU!!!! you have dispelled my fears!! I shall start tomorrow to clean my 11' Celestron! cheers
I know it was an accidental typo, but I suspect you meant 11" Celestron...
An 11' Celestron would REALLY be a baaadass Mutha-Mirra! 😁
@@EleanorPeterson you right Sir, only a typo, and yes, that would be a baaaaadass Mutha!!
I wish you had shown your collimation technique more in detail and explain the home made tool you used. Perhaps make a video on collimation only??
Thank you for this video !!! It gave me the courage to clean all the optics on our Celestron CPC 800 GPS (XLT) computerized telescope. We've had that Telescope for at least 12 or 13 years, but only used it a handful of times. My husband had lost interest. Now my daughter got interested and I helped her set it up. The manual focus was stuck, but I was able to fix that. That left us with a badly dirty corrector and a dirty mirror. I was told we would have to take it somewhere to have this done, but no-one around here does that work and sending it in for something like this seemed crazy expensive on shipping alone. The corrector had a strange film on half of it on the inside, but even that came of nicely. Just finished the work and everything looks good. I don't know much about Telescopes but I'm glad ours finally gets used. Next on our agenda is to find a nice entry level camera that works with this telescope and a couple of better lenses :) Thanks again, I would have never attempted to do this hadn't I found this video !
I love the idea of walking past a C14....to get to the big scope!
Indeed! It may be surprising that the 14 actually outperforms the 16 on sky on most nights!
Really? How come?
@@gregorytack638It can be many things. Better optics, better collimated, better eyepiece, better temperature stabilised, etc.
Thank you, this video gave me the confidence to clean my sons recently purchased CPC 800, it's secondhand and the inside seemed too much dust for my liking. Went through a lot of cotton balls trying to dry up the water :), used a small amount of dish-washing detergent.
Super informative. I have a dirty SCT and this is just the information I need to properly clean the optics. Thanks so much.
This is spectacularly good: informative, educational, confidence-building, along with high production values. Thank you very much.
Thanks very much for the nice feedback. Making the video after gaining confidence cleaning the first telescope, was still a bit of a spur-of-the-moment thing, but I was very glad the way it came out. Editing a few hours of video into a watchable length was the next challenge. The number of views and comments like yours is the reward, thanks again.
Please do carry on the good work Willie.
Great info. I was a little hesitant to clean my C6, but your calm and confidence voice definitely helps. Thank you.
Great to hear. Good luck with your cleaning job.
Your confidence is inspiring, thanks
Thank you Mnr Koorts for posting this great explanatory video. I used the info. to clean my Meade 8" LX10 and it came up beautifully clean. As they say, it's easy when you know how!
Hi just got a 8" Meade cassegrain and glade that I watched this before I tried to clean the telescope thank you for taking the time to post this.
Great to hear! Clear skies!
Excellent video! Thanks for showing each step! Even removing the corrector plates.
Thanks. Glad to hear you enjoyed it.
Well done and much fear dispelled. I will use this to clean my 6" reflector. Thank you, and NICE roll-top building!
Great video and very informative with detail! Thank you!
Thanks. My corrector got covered in dew last night ! You've given me some confidence in cleaning it. Regards.
Wonderful! All the best and clear skies!
VERY interesting how to clean such amazing scopes. Thanks for sharing the procedure. :) Clear skies!
Thanks for the informative video, Mr. Koorts!
Thanks for the video Willie.
Pleasure. Glad to hear you found it useful.
Oh my, that huge 16-inch corrector wobbling on the plastic chair sends shivers down my spine! ;-)
But to each owner their own... work routine, and practice - which you show you have in buckets - more than this C8 owner who only had the guts to go as far as cleaning the corrector plate a few years back (actually my main mirror looked just fine).
Where's the best place to find the supplies?
Dankie vir die demo Willie.
Great and very helpfull video! Thank for the help!
Nice video and voiceover
Thanks for the video. I have a new 8” Celestron but noticed some dirt/dust on the outside of the corrector lens. I’ll try just cleaning that first and maybe that’s all that’s needed.
Sounds good to me - always just clean optics as little as is absolutely necessary. Good luck.
Brave man - I will have a go on mine - it's filthy - was always scared - but very detailed video. Thanks.
Oh the Horror!! Your roll off observatory is AWESOME however!
Thank you for this video. I have just acquired a 10" SCT and there's a small amount of mould on the schmidt-plate glass I have to sort before I can use it.
I found I have the same issue; did you ever get round to it?
@@xptodundee Don NOT clean your optics unless it's AN ABSOLUTE MUST
Nice video. I was cleaned successfully with detergent and clean water. But I removed the prime mirror first. Your way is little more difficult but you don't need to remove the mirror itself. So if that's work you can keep doing that.
Thanks. With both these models, the only way to remove the primary, is unfortunately to remove the corrector first to gain access to the primary's mounting system.
You could add a couple more scopes in that observatory. Nice setup.
Interesting process.
thousand warm respect
Nice cleaning nice telescope nice observatory 👍👍👍👍👍👍
just a very precise way of cleaning the windows
Thanks for taking the time to share this video. Very informative. If you are just cleaning outside of corrector and not removing it would it be best to point tube down to prevent water from running down tube. I just need to clean the outside of mine for now.
Yes, most definitely! You don’t want any water getting inside the tube if you are not planning to access its inside.
thank you for this video
I've gotten really good at doing this too with my 1981 Celestron 8 'Frankenscope' (made of the best parts of two that were heading to the junk pile otherwise), and have gotten to the stage when I can clean the corrector to perfection.
Tools : PEC Pads, Ultra-microfibres, a lens 'flick' microfibre tool - all of the first three from a specialist camera shop; Tamiya masking tape 10mm, Gundam fine markers (for cork positions on masking tapes), cotton balls, X-acto #11 Stainless Steel blades and handle, rubber gloves (not nitriles), 3 x 250ml lab squeeze bottles for cleaning solution, EtOh, dH2O.
Cleaning agents : dH2O, EtOh 95%, Pure SLS (lab grade), and a can of CRL professional hi-sheen aerosol cleaner; Cleaning solution of 20% EtOh:80% dH2O - used to dab on mirrors and correctors with a soaked PEC Pad with zero pressure.
Technique : the same as yours for mirror surfaces; I protect the secondary with a spare cotton glove, but will use the pristine microfibre flick-cloth prior to covering with glove. Dabbing with a cleaning solution pec pad, followed by a tube-down rinse with dH2O, and then dabbed with a pristine ultra-microfibre to prevent micro-spots.
Gloves in use at all stages.
For the corrector - all the same steps for the cleaning, though with absolutely no pressure at any stage of procedings - scratches of even the slightest sort are unforgiveable to me. The soap stage is two-step - SLS first, dry, then CRL spray, blotted, dried - all drying steps with the ultra-microfibres. Done in bright sunlight, to ensure that there are zero streaks or imperfections in the drying stage - about 0.5 Newtons pf pressure is permissible in drying stage, but from the bottom of the corrector being held in-hand by the corrector assembly - the cloth can 'fall away' from the surface, rather than being 'pressed in' and that is super-critical. PEC Pads replace cotton balls for the cleaning stages, when
For drying, because it is light enough, I will do the drying by dragging (with no weight) a pristine micro-fibre over the real surface, using the sun to ensure that there are no scratches, and no dust. Identical technique, and another pristin ultra-micro-fibre (I have three per annual cleaning session) for the front surface.
Result is something not even Celestron say is possible - a better-than-factory clean. In the process, you remove (for old ones like mine) the wax-coat Celestron put on the surfaces, which gave the optics a 'blue tinge' which everyone thought was a coating.
That's about my only addition to the process.
Wow! Very interesting! That's really cool! Thanks for sharing. Good to know I was on the right path at least, but that there is lots of room to improvement! Thanks for watching. Keep up the good work.
@@SterremanWillie Baie gaaf, en dankie meneer.
very cool! But I have a questions what is better look? celestron 1400-inch? or meade 16-inch? what a better quality optics?
This video helped me sell my 10 year old CPC 800.
This video in very informative , thanks for posting it. What is your method to clean eyepieces ?
Hello good vidéo. I have a question :why don't you clean the secondary mirror ? Is it possible without dammage ? Thanks
So, im getting a CGE soon, and im wondering how your 14 holds up on it? im looking into the edge HD, for the mirror locks, but i want to know how your 14 holds on the standard cge
Bravo ; I liked this video
What is the name of the collimation device you used, and do you still need to collimate using star latter? will it work on a celestron 9.5 sct, I am going to have to clean the inside and outside of corrector sometime in the near future. I would probably have it done but there is no one locally that works on telescopes. How much of the sodium sulphate do you mix with water? Forgive me for having to ask so many questions. I am very much dreading having to try this, although you video makes it look pretty straight forward.
hi. if there are yellowish stains on the primary mirror on the edges; is that bad? or what could be the cause: becuse i bought me a telescope that came like this?
thanks for the great video sir..
I heared that dish washing soap is rough.. but this video changed my info... 😊
what about cotton instead of wool?
Willie Koorts thanks again dear sir. u just made me so happy for showing how easy to open and clean the mirrors. I own a 14" EdgeHD SCT. but it's new.. but I was so worried about how to clean it..
thanks again and have a nice day
Hi, I'm really interested in how you achieved your roll off roof assembly. Do you have any other videos regarding the build?
Unfortunately not - the dome was supplied by a contractor. It uses the motor and mechanism of a gate opener to open and close it, using two linear gear racks on both sides.
Cotton has fragments of cotton seed, which is quite abrasive. Get some of the artificial cotton used to clean selenium rollers in Xerox machines, or those micro-fiber "rags" that have no natural fibers.. Especially for mirrors. Apparently glass will sheet on truly clean glass. If it beads up, it isn't clean. I'm not sure if coatings affect this as I have only seen it before coating.
Thank you for the video! Just a couple questions, though: (1) You said to use one or two drops of dish detergent, but in how much water should this be mixed to get the right concentration? (2) If I don't plan (at least initially) on removing the corrector plate, how do I make sure the solution doesn't get inside through the secondary mirror's mount? Would it be helpful to build a little cloth dam, or something like that, to capture the water before it reaches it? Or do I need to aim the tube straight down while cleaning? Thanks!
Hi John. I don't think the detergent strength is too critical, the main idea is not too strong, since it takes a lot of water to rinse it all away again. If we use detergent, we mix 1 tablespoon to 5 litres water or Sodium Laurel Sulphate at 0.8 gr per litre water. Yes, to just clean the corrector's outer surface, the telescope is turned to point to the ground to prevent water getting into the tube - the you can use soap and water liberally. When working upright, something to soak up any spills is a good idea as well (we use exactly this technique with some of our bigger telescopes which cannot be inverted). I did actually get some water in the Meade's tube, but it did not go where anything could be damaged.
i have a 10" schmidt-cassegrain that has some simple, light condensation dust rings on the inside of the corrector plate...honestly, it does not perceptively impair vision...perhaps cuts into magnitude a tad, but i am going to clean it off in the summer, just cuz, i like it looking pristine. if the primary looks clean, which it does, with the plate in place, i wont be touching it.
Thanks for this Willie. I’m planning a visit to Sutherland this winter. I haven’t been there for at least 2 years now. Is this the observatory at SALT? I normally stay at Sterland and use their scopes so haven’t ventured much beyond there. Thanks again for this I’m now going to tackle my scopes. When you find time please consider a detailed video on the collimation.
Not quite at SALT (you can see SALT in the background at the end) - at the Visitors' Centre. Sterkte with the cleaning, it is not difficult. I'm not an expert in collimation and there are numerous videos on TH-cam already, thanks.
That's damn great :)
I just found this great video, so I'm a bit late with the comments and questions, but....I have a Meade 8" SCT made in 1985 and have long been fearful of cleaning the optics due to the UHTC coatings they put on them. I assume this cleaning process won't damage or adversely affect those coatings, right? Also, the video didn't show how you dried the inside of the corrector plate, should I assume you dried the inside of the corrector plate the same as you did the outside of it and the primary mirror? Same process for the secondary mirror? Thanks!
Thanks. Yes, this process, if done correctly, would not damage coatings. Yes, the same procedure for all surfaces - I probably left out the inside of the corrector to save time since the process should be clear by then. Happy cleaning!
Great work buddy just a Quick question my corrector plate has cracked and the is a few small bits in my mirror what would the best way to remove the glass bits from the mirror thanks.
Sorry to hear about your problem. I guess the short answer is, very carefully! Perhaps point the telescope to the ground and try to blow out as much glass as possible first using clean air. If any remains on the mirror, gently brush it off with a soft brush. Hope you can rescue your scope again.
Hello Willie,,
I have NexStar 6SE
But the corrector plate is broken.
How i can get a new one ??
The obvious: contact Celestron customer service.
I had to remove and replace 4 screws in the primary housing to replace the red dot finder and install the starsense
undoing the screws was easy, putting them back in was more difficult especially towards the end with significant forcing
is this abnormal?
Interesting. The back casting is aluminium so normally tap screwthread fine. Sounds like threads were spoiled somewhere, but unless you crossthread the screws, should have been smooth. It could also have been that you mixed metric and imperial - often the threads on the telescopes are imperial.
amazing video. I would 1st try this on a junk Schmidt-Cassegrain to play with before messing with a high dollar OK telescope? 😎 Thank a lot. A budget moving building is the way to go.
Also, I would of thought these Schmidt-Cassegrain telescopes would of kept the dust out better?
I had my SCT in storage for about 6 years. I have a film on the corrector plate and tried your method but I keep getting streaks or what looks like smears. I can't seem to get the glass clean with soap. I even tried the lens cleaner and it leaves a film as well. What am I doing wrong?
wt93205 Soap will leave a film. Get some high purity isopropyl(like 99%) alcohol and distilled water and try that with regular white tissue or kemwipes. (No fragrance or lotion)
+ Astronomer Exactly. I have used hydrogen peroxide 6% to get rid of any mould/fungus spots instantly (and I really do mean instantly), then isopropyl alcohol 99% for grease etc, then de-ionised water for the final cleaning with cotton wool pads.
thank you for the video, well done! I have an older C8 "79 model" is thare a reason you use cotton over pec pads on the mirror?
As long as you know there is nothing nasty hidden in the pads, it should be fine.
@@SterremanWillie cool. mines pretty clean atm but was just a question. thanks again.
My corrector plate and mirrors have anti-reflective coatings on them. Will this wipe off the coatings?
Also, why not use a spray bottle (with your own cleaning solution in it) instead of dabbing the cleaning solution and water on the the glass?
The secondary of my 36-year old SC looks to have some corrosion spots on it. Does it have to be re-aluminized or can I simply clean it?
Edit: spelling.
Anti-reflection coatings are (normally) tough enough to withstand cleaning, so should not be a problem.
If you can afford some dripping from the mirror, using a spray bottle works fine - in fact, you will see it being used in another video I made when we cleaned a giant mirror!
If those spots do not budge after cleaning, you probably need to re-aluminise, yes. Try cleaning first, you don't have anything to loose.
Very interresting. So if i mark my meade lx200r 10 inch telescope like it is done on tge video. I should still be able to use witjout the need for a collimation (no idea what this is and how to do this. Just bought the scope and i want to clean the organic stuff in it.). Hopefully someone can answer me. Great video. Thanks
Yes, the collimation should be preserved if you put back the corrector the way it was. Good luck cleaning your "new" telescope.
Informative video. What is the latitude of this observatory ?
Thanks. 32 degrees south.
What are doing to check the collimation at the end? That would have been very nice to explain. Thank you!
I show both devices, autocollimator and cheshire in the beginning, you can Google that since the video was not about collimation, i just showed this step briefly.
Hi, I have a Schmidt cassegrain telescope that has collected mold on the corrector plate and the primary mirror over time. Would I be able to clean the mold with this method, and how has the mold effected the mirror? It has been sitting in a basement for over 5 years. Thank you.
You don't have much too loose but try. The mould should not have attacked the glass easily. It may have effected the coatings of the mirror/corrector in which case re-coating would be required, but it will definitely help to first try cleaning which will reveal the damage, if any. Good luck.
+ Matthew Same here, alas. I have a 5 " Mak-Cass and an 8" SCT which I had to keep in storage for five years. Last week I took them out and saw the most appalling mould/fungus on the internal surface of the Mak's corrector plate. Oddly (why is this?), there was not even a minuscule trace on the primary mirror. Following Willie's advice and others, I removed the fungus easily with cotton wool tips soaked in 6% hydrogen peroxide, followed by de-ionised water dabbings and then wiping with pure cotton wool pads. Brilliant results. Mercifully, the mould had not etched away the coatings!
The secondary mirror of my Mak had also been populated with a shocking amount of fungus, but in this case - being an externally-silvered mirror - I chose only to use de-ionised water with a single drop of washing up liquid. Dab, dab as Willie showed here, and then wipe only with de-ionised water followed by dry cotton swabs to complete the cleaning. Good as new now.
As to my SCT, I have removed the fungus on the external surface of the Schmidt plate as above. Like my Mak, not a trace of any contamination on the primary mirror. Willie has given me the courage to remove the plate and clean its interior surface. I SHALL be marking the plate with respect to its orientation to the OTA when I do this tomorrow, given that a Schmidt lens is way more complex an optice than a Mak Meniscus. I only hope that the secondary mirror has been spared the ravages my Mak suffered! Wish me luck!
Salutary lesson learned: never store such telescopes in unheated spaces in the dark. And ALWAYS expose them to the Sun every now and then, so that mold/fungus can never take hold.
By having a teeny weeny bit of mould on my C8's main mirror a few years ago, I got rid of it with some light cleaning (though a mark of its same minuscle size was left on its surface - which fortunately doesn't affect IQ in the least) and then, by having learned it thus the hard way, have never left it inside the plastic container it's been stored since without a deumidifier box such as one of these:
www.alibaba.com/product-detail/400ml-500ml-moisture-absorber-box-interior_60115754650.html
This way, I cut out one of the three things fungi need to live on and thrive: moisture. These are so effective that I don't have to worry with the other two (darkness and warm temperatures) which, here in damp, tropical Brazil are a part of life.
I have a Meade 2080 SCT 8” with a scratched main, any ideas where to buy one?
Sorry, no idea. But how badly is it scratched? How did it become scratched? The reason for asking is that the scratches may just be in the coating - I get this often with mirrors that we re-aluminise. If the scratches are just in the coating, they are fine after re-aluminising.
Hello, an interesting video, I also noticed that C14 on the corrector has large scratches, say these scratches have an impact on the image in C14 ?!
Yes, unfortunate, probably due to bad practice when trying to get rid of condensation. The scratches would add to scattered light.
this is because of the cleaning method..
Willie, my seun het Celestron Astromaster 130 EQ en n Celestron vergroot teleskoop, die laas genoemde het nie probleme nie maar die 130 EQ het uit fokus gegaan, dis wat ons vermoed, is daar n manier om dit reg te stel of moet hy iewers heen gestuur word, dis die lig versameling teleskoop. Ons hoor graag van jou, dankie vir video
Hallo Jan. Dis moeilik om te sê sonder om die teleskoop te sien, maar 'n teleskoop se fokus gaan nie regtig uit nie. Ek wonder of dit nie dalk sy kollimasie is wat uit is nie. Kyk bietjie TH-cam video's oor "adjust telescope collimation".
Dankie Willie, sal so maak.
My dream scope. Great video. Thanks for taking your time to make and post this video. Can fogging of the corrector plate and mold on the primary be cleaned? There is a scope for sale that is in good condition but has these 2 problems. Anyone replying would be appreciated.
Thanks. Fogging should be able to be cleaned off (depending what caused it obviously) but mold can sometimes attack the coatings and cause more permanent damage. Beat the price down because of this and hope for the best!
This is a bit late for your situation but someone else reading may take note. I acquired a 12" Meade LX200GPS on March 17 of 2021. Was missing the hand controller cable, power cable and had mold on the primary and inside/outside of the corrector. The idea of taking it apart was a bit intimidating even though I paid basically nothing for the telescope (long story).
Using this video as a guide, I first cleaned up my 8" Celestron. It was another used purchase, there was a significant (to me) amount of dust inside that I had up to that point ignored. Canned air sprayed into the tube with the corrector removed flushed it out gently and I decided to stop there. Cleaned the corrector as shown here. Was rewarded with one of the best views of Saturn I've ever had. Perfect seeing contributed most to that.
With one success story, I turned my attention to the 12" Meade...
Every situation will be different, but in my case the primary cleaned perfectly, and it was the part I was the most worried about, with a dime sized spot of mold visible. There is one very small spot on the corrector where you can see the coating didn't come out of its ordeal quite perfectly, but the glass itself looks fine. This would be less than 1 percent of the actual surface area of the corrector and does not show up in the eyepiece at all. It's really a fantastic telescope. I fought the mount a whole lot more than the optical tube. Meade is in last place for electronics in my eyes, but I think I have all the bugs worked out. The tiredness I feel right now is from being out until 3am with that telescope and having to report to work by 9. Worth it.
Other data points for mold removal. I've had a bunch of eyepieces and also telescopes come in with mold in them over time. I've had good success with them also. It's not necessarily a death knell. The worst of them so far was a 25mm Kellner, the coatings were clearly angry but it resolved a wonderful image still once cleaned. I felt no problem selling that eyepiece along with a telescope, everyone left that deal happy. I thought for sure that eyepiece was destined for the trash before cleaning it.
@SterremanWillie can you tell me what you used to wipe dry your surfaces with.
I used the same cotton wool used for cleaning, to dry the optics. Note, it must be 100% cotton wool, no colouring, scenting, etc.
@SterremanWillie thanks for the advice. Cheers.
I got an old Meade 8" SCT and I did not realize until it actually arrived that this thing does not have a mounting bracket. Any ideas no what should be the next course of action? thanks!
What do mean when you say "mounting bracket"? The bracket that goes onto the mount, or perhaps the mount/tripod itself?
@@SterremanWillie First of all thanks for helping. Second of all sorry for not being clear as I am new to telescopes. So what I meant was the tube didn't come with a Dovetail Rail Assembly or a cradle ring. It is just the tube bare bones. I checked with the Mead cust' service team and they suggested I get in touch with one of their dealers here on the east cost (closest is in NJ) They said it is backordered and would take 8 to 10 weeks minimum. Any other ways I can get this paired with something to put it on a tripod? Thanks
@@Astro_Gyani thanks for the explanation, makes better sense now. Wow, that is a long lead time! I would suggest you try and contact amateur astronomy clubs in your vicinity, particularly those which have active ATM (Amateur Telescope Making) groups. If is amazing what people have laying around in their garages and well stocked junk boxes and what ingenuity ATMs can come up with! Hope you can get sorted soon!
@@SterremanWillie Thanks I was just checking out which clubs are operational here esp. due the resurgence of covid and the cases jumping up on the East coast. I think there are a few clubs and one has an online zoom meet in the coming week and I am planning to join in and see if they have ideas. Thanks for the help! Really appreciated.
This man makes it look easy. But don't think it's a casual job in any way. If there's any resistance when you're putting the screws back in, stop, see what's causing the obstruction and even if you have to remove all the screws again, do it. I thought I was being careful but it didn't stop a crack developing shortly after. I may still be in shock, but please, don't attempt this unless you really have to and you're 100% alert.
What do you exactly use to make collimation after, please ?
I only checked the collimation using two types of tools, a Chesire and Autocollimator. Should it would have been required to the adjust the collimation, I would have adjusted the collimation screws on the secondary mirror mount.
please what size bolts hold the mirror in mine are rusty and the 2mm allan key is to small and 2.5 feels to big
As far as I remember all sizes were imperial on this telescope, which will explain what you found.
@@SterremanWillie many thx
Thank you for the great video. I have a question about this. What can I do to find the correct position of the corrector plate if I have removed it before I knew it must be indexed a certain way? My problem is that I have taken it apart once and didn't mark it for reassembly. Thank you, Scott
Hi Scott. All I can think is to inspect the corrector and telescope tube very closely to see if there are not perhaps any matching markings put there by the manufacturer. On the other hand, I'm not too sure how important it is for the corrector to have a specific orientation - in theory a properly made corrector should be symmetrical all around and therefore should not matter how it is assembled. If you can collimate it properly (including on an out-of-focus star), it should be fine.
+ Willie Great video, thank you. It has given me confidence to open mine in order to get rid of a number of spidery fungus spots. I think I have killed them by exposure to the Sun, but they annoy me ;).
I noticed you DID mark the orientation of the corrector plate with respect to the OTA - presumably as good practice. I believe it matters less with Mak-Cassegrain scopes since their meniscus lens is easier to manufacture totally symmetrical. The Schmidt SCT plate on the other hand is a wavy affair and far more difficult to manufacture and collimate! I believe this was the main reason for the development of the Mak over the SCT.
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Overall, very helpful.
However, the cleaning of precision optics, especially first surface coated mirrors, using a process involving touching, is VERY RISKY, insofar as damage to coating and surface polish (microroughness) is concerned. Why not use “First Contact,” or nitrocellulose collodion (reagent grade), which are strippable coatings that pour on, dry, strip off, involve no wiping or rubbing, yet result in atomically clean surfaces?
What about the secondary mirror?
When I saw, how you uncovered the "shack" with the telescopes... Wow! Where's the "I like" button???
Willie why does it matter how the corrector plate was originally rotated? Isn't the surface of the corrector the same regardless of rotation?
In theory rotation should not matter yes. On the other side, optical tolerances are so small, that it is always better to be safe than sorry, particularly if all it takes is to mark. It is such an ingrained habit in all optical workers to do it, probably dating from the days of older, handmade optics.
Willie when you do collimation of an SCT do you FIRST need to perform an alignment before attempting an in/out-of focus star test? In my case the star keeps on drifting out of view
The video only shows the daytime collimation (which did not need adjustment) - this is followed up at night on a bright star with high magnification and rack in out of focus yes. If the star drifts out of focus as you describe, I can think of two possible causes: (1) something is loose/worn causing the focus to physically move, or (2) the seeing conditions were bad, making it difficult to focus and it actually drifts due to seeing changes.
It is absolutely necessary to mark the orientation of the corrector plate! They manufacture these optics as a matching set, the flaws in one cancels out the flaws in the other but only if they are oriented correctly. They try several plates on each mirror until they get one that works the best. But the rotation of the optics has to stay the same.
That's why if you need another corrector plate you have to send in the whole telescope, or at least the optical tube so they can match it up.
+ butlertv1 The SCT corrector plate is far more complex (wavy) than the meniscus lens of a Mak, which is why orientation for the Mak plate is less critical. At least that seems to be the consensus.
Great viewing :-) why does nobody ever clean their secondary? Mind blowing scopes and observatory!
Thanks for the remarks. Good question about the secondary, probably because it is well sheltered, so keeps clean by itself. I assume you watched some of my other videos showing the other telescopes at the Sutherland Observatory.
Nice observatory
Very helpful and I appreciate your effort. I am having a hard time finding a good video on collimating a Celestron SCT telescope. By good, I mean one that covers the equipment used and the procedure. Willie mentioned a Cheshire and an Autocollimator in another reply. Do they work together? I will appreciate any links to collimating.
I have one on my page, in case you haven’t found one yet.
how many granular in the water
Mix 0.8g SLS per litre of deionised water
He's braver than me.
As a professional photographer I'd never put any liquid on a lens directly, nor in such amounts as to form drops that could get in between the lens element/glass filter and the ring holding it in place. I would think if you had a cemented double lens that any liquid could get in between the lenses and play havoc with the cement. With a SCT you run the risk of water getting inside the tube and causing damage. (Ever see mold growing inside a photographic lens?)
In photography you'd first blow any loose particles off with compressed air (use caution) or clean blower brush positioning the front of the lens horizontally or facing downwards so that any dirt falls away from the lens and not re-deposited on it. FOr any stubborn dirt I'd lightly use a dry tissue or clean microfiber cloth then follow up with a DAMP, lint free, tissue or cloth and lightly wipe the glass in a circular motion with multiple tissues if needed until clean.
If you had no other option than to use dish soap (which is actually a detergent) and distilled water you only need a drop or two of the detergent. This is how professional window cleaners work. You only need enough detergent to break surface tension.
Forgetting that, before you do anything I'd first read the scope's manual for cleaning instructions or contact the manufacturer repair department for instructions.
Here is a safer way to clean your corrector. th-cam.com/video/2cMbivz-hrM/w-d-xo.html
I disagree with his use of the word 'firmly' when wiping with the Pec Pads (Pec Pads are something I use myself). Lightly wipe so you don't grind and dirt into the glass causing scratched or damaging fragile coatings.
Correct Robert, I would not do such with compound lenses either where the capillary effect is a huge problem. However, both the corrector lens and the primary mirror of a SCT are single elements, so no danger here.
Regarding detergent strength, I agree 100% (and say so in the video) to use a very weak solution.
Not sure where you got the reference to Pec Pads from - there is no mention of this in my video.
The methods I employed in my video, were derived from methods used by our optical specialists in our professional astronomical telescopes at SAAO/SALT.
Sorry, I only watched the Starizona video after replying, so now see that the reference to Pec Pads is from this video. I would never wipe an optical surface (like the guy in the video, who does not even wear gloves) while there is dust present on it. It does not matter how soft a cloth you use or how lightly you wipe, it is the dust already on the surface that does the (micro-)scratching.
I would never use compressed air as it contains moisture, nor would I use microfibre cloths. It is very important to use fresh cotton wool as described in the video, all microfibre cloths do is transfer the dirt/oil to other parts of the lens. Also NEVER use a circular motion, it is the worst possible thing you can do. Willie's video is spot on for an SCT.
"wipe the glass in a circular motion" No! never do that if there is any abrasive particle you will scratch the optic pretty badly even if you change your pad frequently. Photographers exaggerate on the cleanliness of their optics and many times they end up doing more damage by cleaning so frequently and incorrectly than if they leaved their optics dirty. Here is a good tutorial from an optics company, they work with laser optics and many times the optics need to be immaculately clean or else a speck of dust could cause a break down and damage the optic due the intense laser light. None of the techniques involve circular motions, all of them are linear. th-cam.com/video/9Pq4SeNmFYw/w-d-xo.html
The very best indicator (for me) when buying an OTA or Oculars is the phrase, "never needed cleaning" In the best regard, meaning it has been cared for in such a way and handles that as such, its needed no cleaning, save for some puffs from a dust puffer.
A question did cross my mind, since i've not needed to clean my OTA- once contaminants are removed, would a squeegee either with a cotton wrapping, or just the rubber, be a useful way to remove remaining water saving so much wiping?
I'd be terrified to dismantle my scopes!
If done with caution, concentration and care is way simpler than it looks like.
Scary stuff! I've just realised that I watched the whole procedure whilst holding my breath. Can I breathe out yet? 🙂
Hehe! Yes, please, I don't want any deaths on my watch! ;-) ;-)
Great video however, in the beginning of the video you show a view of the "cleaned" C14 and the corrector plate is badly scratched. A little dis-concerning.......
Thanks Mike. Yes, unfortunately the users tried drying it in high humidity conditions which caused the scratching!
:'(
"Disconcerting." No hyphen.
what happens if we dont put schmidt plate correctly ?
If it gets rotated it is probably fine but if inverted or skew the telescope will by useless
@@SterremanWillie thank you for the answer.
Unfortunately Sodium Lauryl Sulphate (SLS) has been banned in the EU because of its skin irritation properties, what would be a pure alternative?
That's a bummer. For home use to clean mirrors, I always use uncented dishwashing soap. I saw older recepies using Teepol.
@@SterremanWillie What about SCS (Sodium Coco Sulfate)?
@@pereguerra7742 Sorry, I have no idea. I recall SLS was the base material of all soaps, so there must be a new product after SLS has been taken off the market.
Good Tutorial.. But Why/how did You Clean The Mirror By Rubbing On It..o though You would Dip it in water and Use Tissue Paper to Dry it Out🔭👍
As you have seen, you first dab until all the grid has been removed, before you can start rubbing (very carefully!). Only use pure cotton wool to dry the mirror - you never know what can hide in tissue paper.
Wish I'd have remembered to orient the plate on my C9.25 SCT back to the it's original position last week, then it might not have developed a hideous crack 10 minutes later. Or maybe it was a tight screw?
Never mind. Help is on the way; not too expensive, I hope.
Oh no! What a pity! Yes, those correctors are not very thick and cannot take much force when pinched! Great to hear you could find a replacement corrector! Hope you are up and running again soon!
@@SterremanWillie Thanks.
I had the same accident! Please let me know if you find any hope for us!
@@henningjacobs6875 Celestron tech support UK can provide a new plate for around £170, but finding a company who will competently fit it for optimal performance is proving trickier. Do you think you know where you went wrong?
@@mrh9635 fitting the Celestron dew heater ring. Everything OK. Till the last tightening of the last screw!
Cotton wool, like cotton balls?
As long as they are 100% pure cotton. No fancy additives, perfumes, colouring, etc.
@@SterremanWillie Okay, thanks! And you use the cotton balls for both cleaning and drying?
@@d3ci.b3L yes, for drying make specifically sure they are pure cotton, to prevent possible streaking.
Wow is this really possible to rub the mirror like this?
Only after its gone through the whole process and using the correct material is it safe to do.
@@SterremanWillie is it also possible for any mirrors such as a 10" Dobsonian one? Or is it just possible with the best mirrors?
@@oupwo7468 Not sure if I understand the question correctly. All mirrors, professional or amateur, pyrex or plate glass, etc. get exactly the same treatment.
@@SterremanWillie Are you sure about that? I mean.. Some mirrors are pirex, some are zerodur, I heard somewhere from an astronomy channel that some mirrors are cheapers that others. Is the coating axactly the same everywhere?
@@oupwo7468 Indeed! The glass is just a (very accurate) carrier of the reflective layer, which is what is doing the work.
There shouldn't be any dust in the telescopes, for that amount of money what they cost. Am I right ? Great video.
Thanks. The Meade actually has a fan at the back to circulate air through the telescope tube. The system does have a filter in, but it could still force damp air through the tube, causing condensation, which left residue on the mirror surface I think.
@@SterremanWillie
Thanks for the reply.
Yes that's true but it shouldn't be a problem to get the telescopes better sealed. But this is just my opinion. Have a great day.
Nice job, but from my actual experience i think the main mirror was cleaned a bit too hard.
Now if there's another cleaning mechanics, i don't know.Hope you don't have any significant scratches on it!
Peace❤
Thanks for your comment and for watching my video. Peace2