Moonshed

I have just started using my ‘scope again this winter for the first time since last year and I am having trouble with the Polemaster, it has always worked brilliantly before, I’ve had it about 2 years. I am now finding that after selecting the first star and rotating my ‘scope for the first time it keeps looping back and asks me to pick my first star again. I can’t figure out what is wrong. I went back to Modern Astronomy, who are so helpful, and they gave me a new link to download the latest software but unfortunately nothing seems to happen when I download it and the driver as well. Do I need to remove the existing Polemaster programme from my laptop before downloading the new one? I am also suspicious of the cable that locks into the Polemaster camera as it looks a bit lumpy and bumpy and think I may need to get a new one, they only cost £19 anyway. Has anyone else had a similar problem and know how to fix it? The Polemaster has been so useful I am now lost without it.

Well, so far so good. Your photographs are amazing, I especially like your M31 image, great detail and colour.

I agree with your thoughts on mirror cleaning and that common sense should prevail. I doubt if I will need to clean mine again, by the time it needs cleaning I will have probably be pushing up the daisies. Obviously the interval between cleans depends very much on individual circumstances and the situation you are in demands regular cleaning, whereas in my case, living about 5 miles from the coast, not so often. Having said that, leaving it for 35 years was clearly way too long and I really should have cleaned it years ago but was too cowardly, however, I am now a super hero and fear no mirror!🎖 It does make sense to me to keep it clean in the same way that we keep our lenses, eyepieces and cameras clean. Sometimes the condensation here around November time can be horrendous and after a night’s observing everything will be wet so in that situation my case of optical bits and bobs comes indoors instead of staying in the “Moonshed” ( so named by my granddaughter and been called that ever since, hence my sign-in name) and everything gets a good clean. Makes sense to me to keep everything clean.

Good advice, and the website on cleaning mirrors is also good. I think you have summed it up nicely with your remark that it’s all just common sense, because when you get down to it, it is!

Stu, you are right! I should not be put off from posting my thoughts just because a very small minority are know-it-all highly critical people who love to put people down. You may find this hard to believe, but then maybe not, but one of that group, who has posted here, first responded to a post of mine about two years ago when I was starting out in digital astrophotography for the first time, previously having used a film camera. There was so much to learn, people talking about flats, darks, lights, bias, exposure times and number of frames, stacking, and not to mention the complexities of Photoshop. People were so helpful and gave me so much help and advice, except one or two that is. One in particular said that with my set-up I should forget all about imaging deep sky objects and instead content myself with the moon and solar system! When I eventually produced a nice image of the Orion Nebula many members said it was a good first start and to carry on and get more practice and gave me some good tips, his only comment was to say the image was awful, all nebula. Not once has he given me helpful and constructive criticism, just put downs. Can you believe that? Why do people do that? If they cannot find something good to say or offer helpful advice then they should not say anything! He hasn’t changed one iota. It seems to me it doesn’t matter where you go you will always find a small minority of people like that, I usually just ignore them because the vast majority of people, here and elsewhere, are nice, decent, helpful people who genuinely want to help you succeed in your new venture. For that reason I will not be put off by the few nasty critics here but will continue to post in my usual way. Thanks for the good advice, much appreciated!

I had a look at your website and have to say the advice you give is both good and clear, easy to follow. Well done on a good job, I am sure it will be a great help to many first timers on how to properly clean their primary mirror. Well done.

No Stu, you have not definitely not failed you have helped, I understand exactly where you are coming from and understand the points you are making, with or without smileys 👍. Perhaps in future posts, should the subject rear its ugly head again, (Oh No the Moderator cries!!!) those against mirror cleaning should simply clarify that if not done correctly damage could be done to the mirror (which to be honest I would have thought to be blindingly obvious) so before starting out just be sure they have thoroughly researched how it should be done properly to avoid any possibility of scratching, and that being done then go ahead and clean the mirror if it looks dirty. On the other hand it may not be necessary as some dirt apparently makes very little difference, so if you are not confident in your ability to do no damage then leave it alone. I think that neatly sums up all the anti-cleaning brigade points so as not to mislead any beginners. Are we all happy with that? Funny isn’t it? I started this thread solely for the benefit of virgin mirror cleaners, who, like me, are afraid to clean the mirror. My first “serious” ‘scope is the 8” SCT I currently own and I bought it second hand as I could not afford a new one back then and I felt that surely today there must be others in the same financial boat I was in. It can be very difficult to justify spending say £1500 on a brand new ‘scope and mount etc. when there is a mortgage and bills to pay and kids to raise, Oh, yes, I remember it well. Buying a used ‘scope makes a lot of sense when on a tight budget, as most of us are? But sometimes they may need a little TLC, and dare I say it, some mirror cleaning may be necessary. I eventually found that cleaning the mirror in situ to be such a simple thing to do that I just wanted to let others, principally beginners, appreciate that it was in fact very easy and straightforward to do and not to be afraid of doing it. That was my intention in its entirety, to help others, nothing more, I meant well. I had no idea the hornet’s nest it would stir up with so many members being so critical of my every comment, I would never have thought it. Had I known in advance the reaction my “helpful” post would create I would never have said a single word, it’s just not worth it. Next time I want to be helpful I will resist the temptation and think back on what happened here and think again.

I think it is obvious that before tackling cleaning a mirror for the first time that a lot of research would be done first. As I pointed out there are no end of videos on YouTube showing exactly how the job should be done and I watched quite a few of them before cleaning the mirror. I did not go into it blind, I knew exactly what I was doing so there was no chance of me scratching the mirror or in any way causing damage. Looking at the comments posted by those that say I should leave a dirty mirror alone in case I scratch it or whatever, it does give a very strong impression that they must think me daft because that is exactly how it comes across. You may think otherwise but I am not alone in thinking this, that’s all I am saying. I have grown tired of this, it is endless, every time I say things could only get better not worse after cleaning the mirror, without exception along comes someone who says to leave it alone because it could get scratched. I give up, there was not the slightest risk of me scratching it, I have been observing since 1960 and have a pretty sound knowledge of looking after and cleaning lenses and a reflector mirror that was easy to remove. I have no wish to explain yet again why I cleaned the mirror so will not bother to respond to those that say I should have left it dirty, even though the outcome is very positive. I hope nobody takes offence, none meant 👍😀😍😆😇

I think it has been made abundantly clear on this thread that some people don't agree with cleaning a mirror that looks dirty. Okay, got it! Honest! However, it just so happens that it is my personal view that my mirror was dirty enough to need cleaning so I cleaned it. I take the view, which I have already repeated, that if it didn’t need cleaning then so what, no harm done, just a little time spent on maintenance that perhaps wasn’t necessary. I, unfortunately, do not posses the skills necessary to be able to eyeball a mirror and tell if the grime needs removing or not, so take the view that if in doubt then clean it. Okay, others disagree and feel it best to leave it as it is. That to me though, to be honest, is just bizarre and illogical, because by cleaning a mirror it will either improve it or make no difference and as I lack the skills to tell which, then I will clean it as it’s everything to gain and nothing to lose. Maybe you could define what you mean by “pretty dirty” because that is just a subjective assessment and not a scientific reading of an instrument. Perhaps someone instead of saying it isn’t necessary to clean a dirty mirror will be good enough to explain to me how on earth you can tell, just by looking at a dirty mirror, if it needs a clean or not, because I have no idea on how to do that, which is why I cleaned it. Many thanks in advance. ps I take it that when you referred to cleaning refractors you were referring to cleaning the lenses as of course they don’t have mirrors. Or perhaps it was a typo and you meant to say reflectors? Just saying for clarification as this thread will read by people in the future.

You made your own 14”? Wow, that’s impressive! I am pretty sure I could grind a blank, maybe, sort of, perhaps, but that’s as far as I would get, no mechanical construction skills I’m afraid and my electrics run to changing a plug. When I was young my brother and I would think nothing of lifting out a car engine in the street and putting in new big ends, or replacing a broken synchromesh gear in the gearbox, but fixing things is very different to making things. Flying rc helicopters sounds difficult but fun, I used to watch the local club fly their planes near where I used to live in Scotland, but it wasn’t for me, I took up gliding instead and absolutely loved it. Flying gliders was the one hobby I loved as much as astronomy until ill health unfortunately put a stop to it. Enough reminiscing, waiting for another clear night to use my super clean mirror! Of course since I cleaned and collimated it there has been constant cloud cover, such is life. Well done on taking on a physics/astronomy degree, bet it’s fascinating stuff you are learning. Good luck with that.

Yes, you make a good point about it being easy to miss-read the tone of the posts when English isn’t the first language. I just felt that by cleaning the mirror I had nothing to lose apart from wasting a little time.

That all depends on what you would describe as “a small amount of dirt”. The mirror looked to me as though it needed cleaning so I cleaned it. What’s the problem? The worst that could happen is that cleaning it makes no discernible improvement, but on the other hand it could result in definite improvement. When I saw them cleaning the 200”at Mt. Palomar on YouTube I decided that if they think it’s a good idea then that’s good enough for me. I am delighted with the result. Those that don’t like the idea of cleaning their mirror don’t have to, their choice.

Thank you. It’s amazing I actually managed it!

Yes, I am very glad I have cleaned it, I am sure it will go a long way to improving my images. Glad to see you have returned to the fold. Things have changed a lot since I started all those years ago, the mounts have become very accurate and the GOTO function saves a lot of time and trouble. The computer software for on screen viewing and controlling has come on in leaps and bounds, as has imaging editing programmes such as Photoshop. The one thing that has not changed much is the ‘scope itself, although the advertisers make impressive claims about mirror accuracy and resolution. It’s a great hobby, the only one that has stayed with me since I was a kid. Sky At Night did a special offer, it must have been around 1960, in conjunction with Charles Frank of Glasgow for a very cheap 4” reflector with a table top mount. The mirror was held in place by what was in effect a bicycle clip. I will never forget my first look at the Milky Way, I was blown away! That amazement at the beauty of the universe has never left me, what better hobby is there?

Thanks for that. I agree that faffing about with the gear is part of the enjoyment. My brother-in-law for example is a keen angler and spends way more time in his shed messing about with his gear than he does fishing, a bit like me and my telescope. 😊

Just a brief update. Had a clear night so took the opportunity to collimate my ‘scope, as it happens it took very little adjustment, much to my surprise. The stars are pin sharp and bright, perfect images, and I am very pleased with the result. Now it’s done and turned out to be so easy to do I wish I had done it years ago, but at least it’s done now.

I cannot speak with any previous experience that would prove that cleaning the primary mirror would result in any improvement, it’s just my belief. When I saw the exposed mirror for the first time, that had never been cleaned in 35 years, it appeared to have a rather dull finish to it, so I cleaned it. After cleaning it looked a lot better, cleaner, brighter, and because it looked brighter that would suggest to me at least that it was reflecting more light than previously, which has to be a good thing. We are always told how “every photon counts” and we work really hard, especially in astrophotography, to collect every single photon we possibly can. The only piece of equipment that collects and focuses those photons, is the primary mirror, the secondary mirror of course can only work with the photons it is given. It just makes perfect sense to me that the condition of the primary mirror must be crucial to the end result and must therefore be looked after. It makes little sense to me if the mirror is manufactured to a degree of accuracy of say 0.57 arc seconds resolution but is covered in grime, but then again maybe that’s just me being stupid. It was never my intention to start an argument about the pros of cons of mirror cleaning, I was merely trying to be helpful but instead have been shouted down. So be it, but nothing will ever change my mind that it is beneficial to clean a dirty mirror, you wouldn’t use a dirty eyepiece, so why use a dirty mirror? There are tons of videos on YouTube showing how to clean a primary mirror, but I guess all those guys that think it’s a good idea must be wrong. There is also a video showing the cleaning of the 200” mirror at Mt. Palomar, they must all be wrong as well. I however remain convinced that a clean mirror is even more important than a clean eyepiece. I have said my piece, I will leave it for others to make up their own minds. Good luck.

Glad to hear that after 10 years you have not needed to clean your Dob’s primary mirror. When it comes to mirror cleaning I personally don’t consider it necessary to wait until an astronomical telescope’s mirror is covered in cobwebs and cockroach muck before cleaning it, a little surface coating of grime and dust is enough to get me cleaning, call me fussy. Let me know how you feel about cleaning your Dob’s mirror after another 25 years, on second thoughts, don’t bother, I will long gone by then and beyond caring.

Yes, I am delighted with the results, the mirror looks so clean now, not really surprising after 35 years without a clean. Last year was my first full year of astrophotography using a digital camera, previously I used film. I received a great deal of help here on how to do it, otherwise I would have really struggled, people have been so helpful. I am looking forward to seeing if a clean mirror will result in a visible improvement in my images, in particular I will compare with last January’s images of M51 Whirlpool Galaxy and M81 Bode’s Galaxy using the exact same exposure times and number. I will be happy to post up the results.

I don’t understand why you are taking my use of the word “sparkle” so very literally, it was just a throw away remark to describe how clean the mirror is. The mirror has not the slightest single scratch on it, that I can guarantee. I have owned a telescope of one sort or another for the last 58 years and I am therefore fully aware that even cotton wall can scratch a mirror. I first used a hand squeeze air puffer to gently blow away any objects on the surface that could cause scratches. Then using water with a weak mix of washing up liquid I gently dabbed the mirror with cotton wool. After that I dabbed it dry. Then I dabbed it with distilled water until all the soap was gone and then dabbed it dry. I repeated it with distilled water again to make sure all traces had gone and then again dabbed it dry. The finished article looks great, it doesn’t actually sparkle, caused by scattered reflected photons, it’s just that clean. I hope that’s finally put that to bed. I appreciate that removing the mirror and thus being able to give it a good flush with distilled water would be the ideal way of doing it. However, not everyone has the ability or skill to take on such a high risk endeavour and in my case at the age of 73 and with a damaged spine, courtesy of advanced prostate cancer, it is beyond my physical abilities which is why I made do with cleaning it in situ, it did the job. I appreciate that you are unaware of my physical disabilities but even fit and healthy people may baulk at removing the mirror and you seem to assume it’s something we could all do. Not so. I wish I had never bothered with this post, I deliberately put it in the Getting Started section as an encouragement to beginners who may, like me, have started out with a second hand ‘scope. I did not expect my remarks to be criticised by an experienced observer who owns a number of ‘scopes and who must think I am dumb. Anyway, I will leave it there, I have no interest in pursuing this conversation.

Seems very odd. Usually when having serious problems achieving star alignment it’s either down to wrong location data or using the wrong time or not allowing for summer/winter time changes. A friend of mine just starting spent ages trying to solve the problem before realising he had entered the Lat and Long data incorrectly, even starting off mixing up being east or west of the Greenwich meridian. You though appear certain you have done everything right. How do you do your polar alignment? You mention that after you have done it you set up the weights and tube. This seems to me to be an odd way of doing it, why not completely set up the whole lot, scope and weights and everything else you will be using, and then do your polar alignment? That way you will not run the risk of moving the mount away from polar alignment when you add the rest of the gear. Also try using the handset for all the stars, including the first, I have never released the clutches and moved the tube manually for the first star, seems a waste of time as it will not know where it is aimed at after starting from the parked/home position and makes that first star alignment rather pointless. After doing my PA, I use a Polemaster for photographic accuracy, I only use two star alignment as with my system that allows me to name the two stars I wish to use so I can select a good spread across the sky and both away from Polaris for better accuracy. I find that with both stars the mount will move close enough so that the star will definitely be visible in the eyepiece but will need a little adjustment using the handset to get it precisely centered. Anyway, keep trying and check everything, I am sure you will sort it out eventually and find it was something easy to fix. Good luck.

Yes, I did replace the corrector plate in the exact same position, the importance of this was stated in the video. The reason I cleaned the mirror was because although it didn’t look dirty as such I could see some spots on it and reasoned that after 35 years it probably needed it, I wasn’t wrong because there was a noticeable difference in the before and after look of it. No, the sparkle is not due to scratches, just a bright clean shine, my goodness, do you think I used emery paper? The reason for looking forward to the dark nights was, as stated, to re-photograph a couple of galaxies to see if they look any better, I am of course well aware that there are currently objects in the night sky to observe. I have to say I do not like the condescending tone of your post, you come across as a highly critical know-it-all, tone it down a tad. Good luck to you too.

I own an 8” Celestron that was manufactured circa 1985 and I have owned it for the last 30 years. During this time I have never cleaned the mirror, being too scared to do so. It has been bothering me lately so I looked on YouTube and saw a guy demonstrating how to do it with a very similar looking 8” Celestron. It involved no more than unscrewing 6 small screws that held the retaining ring for the top corrector plate and lifting it out. This exposed the main mirror which I could easily reach down to and clean as shown on YouTube, as well as the secondary mirror and corrector plate of course. The mirror had not looked dirty, but the difference after cleaning was remarkable, it sparkled! I can’t wait for the dark nights to return and revisit a couple of galaxies I photographed last year and take them again to see the difference, hopefully there will be an improvement. I will of course need to do some collimating first!

I have an extra item on the list. Stick note on back door telling wife not to switch the outside light on when she lets the dogs out.

No problem, I realised you were talking about a Newtonian, I had one previously and it was relatively easy to clean. I have decided not to clean mine, leave well alone.