Relpet

Thanks. That was the exact advice I followed. Unfortunately I think his mirror wasn't in the same state as mine with no advice on how to remove stubborn muck without rubbing. Got a clear view of M42 tonight and the difference was remarkable. Next tiem I might try cotton buds with stronger detergent just on some isolated spots and see what happens..

Last summer I bought, second-hand, an Orion Optics UK 12" Dobsonian. Unable to spend the summer in France, as I have been able to for the last 12 years, I needed a telescope in UK as a cheap substitute for the kit I keep in France. Gumtree gave me the opportunity to keep my eye in. The 'scope from Gumtree was clearly of an age that was reflected in the price but working on the principle that something that basic should be usable in spite of its years I took a chance. The secondary was badly misaligned to a degree that made it impossible to test the 'scope but a squint down the tube at the main mirror was fundamentally reassuring. I parted with the cash, took it home, upgraded the museum piece pretending to be a finder and even under the heavily-light-polluted skies near Gatwick Airport managed to get some decent views of Saturn, Jupiter, Mars and the moon. However, light-pollution could not be entirely blamed for less than perfect observing. A closer look at the main mirror showed an accumulation of about 20 years of dust and dried condensation. I don't have space to work with anything that big in England so brought the 'scope down a couple of weeks ago to France where it will take up permanent residence. Another look at the main mirror yesterday reminded me that the 'scope had been stored in an upright position in a shed where the owner had kept a variety of small animals in cages. The 'scope had not been used for some years as the elderly owner's eyes were no longer able to afford any pleasure from observing. I guess he had decided he needed the space taken up to make room for more ferrets. So, today I set about cleaning the main mirror. I was stunned by the difference and the pictures might give some idea. The mirror is pictured more or less in the same position before and after, reflecting the beams and floor boards in the ceiling above. They are barely visible in the Before shot. However this lengthy preamble brings me to my question. In the After picture there are spots on the mirror showing as highlights. I had followed standard procedure and let the mirror soak in slightly soapy water for about half an hour giving it an occasional swirl. After disposing of the first wash I used rather warmer water, again with a few drops of washing up liquid, for about fifteen minutes while wiping cotton pads under water across the mirror with no pressure other than the weight of the sodden pads. I then removed the mirror and using fresh pads soaked in the water gently passed them across the surface, discarding each pad after every pass. Job completed I rinsed the mirror in de-ionised water, then stood it on end and rinsed again. Any drops that failed to run off were soaked up with a corned of kitchen towel. Only after completing the task did I then notice that some spots, presumably deposited as the end product of the digestive processes of long-dead flies or spiders, had failed to clear. So, any advice please on how to remove these deposits without resorting to a Brillo pad? The mirror is back in the 'scope now (amazingly without losing collimation) but I'm happy to start over.

I had cataracts removed from both eyes a few years ago. The transformation was amazing. Sufferers are rarely aware of the gradual loss of vision so when the mistiness is cleared away the sudden impact of renewed clarity of everything around them can be astounding. To make out every leaf on a tree again, every blade of grass on a village green can be quite wonderful. The replacement, artificial, lenses replacing the clouded natural ones are fixed focus (under the NHS at least) and are slightly smaller than the natural lenses. Driving at night can be a problem for a couple of years as oncoming headlights can strike the edges of the new lenses and defract across the eye causing dazzle but that reduces as the enclosing tissue grows to meet the edges. I have glaucoma also which, if not caught in time, can cause permanent damage to the eye. Treatment with drops or surgery can halt the degradation but my right eye, the one most convenient for observing, was the worst affected and I do have trouble focusing at times. Without the treatment that I started about eight years ago, though, I would probably find astronomy impossible now. Specsavers spotted the glaucoma in the first place and referred me to my GP. A lot of opticians give free eye tests these days. Take advantage of them! What you may not notice they certainly will.

G'day MarsG76. You put me on the right track. Selected compatibility with Windows 7 and it installed in under a minute.

Thanks. I ran the compatibility test several times and it failed every time. Celestron have responded with a stock reply buy promise to get back to me.

Having just become the proud owner of my first computerised telescope, a Celestron NexStar 4se, I want to use it to the full, including operating from a laptop. Only problem is the software on the CD won't install, neither will the latest download from the Celestron site. This is what I get. ERRORNexRemote (1.7.23) is not allowed to run on Win (6.2)Setup Aborted!I have contacted Celestron but if anyone has found a solution I'd love to know about it. It's a Fujitsu Siemens laptop with Windows 10 upgraded from Windows 7.