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About Relpet

  • Rank
    Star Forming

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  • Gender
  • Interests
    Astronomy, films, history books, French Resistance, sitting in the sun pondering the ineffable mysteries of life.
  • Location
    South-west France
  1. Relpet

    Cleaning a 12" mirror

    Thanks, Mike. De-ionised water is the most readily available here but I'll check the pet shops next time.
  2. Relpet

    I've spotted something interesting.

    I was taking some shots of the moon earlier this evening when the sky was still quite light so the features you mention may not be as brightly lit in my picture as when you saw them I've looked all along the terminator and arrowed what I think you might be referring to. Hope this helps.
  3. Relpet

    Cleaning a 12" mirror

    Thanks, Peter. I am convinced the spots are biological. Some of the spots made streaks when I passed the cotton pads across but I've followed Kirkster501s advice and left alone. Lunar observation has been simply phenomenal since the clean.
  4. Relpet

    Cleaning a 12" mirror

    Right you are, guv'nor. When I saw details of the moon last night in crispness I had never seen before I guessed it was either the particular angle of the sun emphasising the relief that night, exceptional seeing conditions, or the mirror was -at last - performing to expectation. (Or maybe all three!).
  5. Relpet

    Cleaning a 12" mirror

    Cheers, Stu. Every time I get down to France there's so much brush clearance, weeding, digging etc I'm quite the horny-handed son of the soil. My fingers might take a month to soften but, as you suspected, the seeing tonight was a revelation. and no indication of the quite minor bemishes still on the mirror.
  6. Relpet

    Cleaning a 12" mirror

    Thanks, David. On leaving school in 1956 I worked in a lab cleaning glassware, amongst other things. We always rinsed out with industrial methylated spirits to clear water droplets and leave the apparatus clinically clean. I was reminded of this when I was faced with droplets all over the mirror but the closest thing to IMS in the drinks cupboard was gin - and I could think of a better use. The Baader wonder fluid looks like a good tip.
  7. Relpet

    Cleaning a 12" mirror

    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..
  8. 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.
  9. As you might imagine, pushing my contraption up a steepish cart track isn't something I want to do that often. On this occasion the chap reconstructing the windmill was on site so I was able to show him Jupiter, Saturn and Mars in a different part of the sky before totally blowing his mind with the craters of the moon. One of the few clear nights last summer.
  10. Here's my 12" OOUK Dob on a padded sack truck, acquired specifically for observing Mars in 2018 when I was going to be stuck in UK for the summer. The mount and EPs go in a wheelbarrow. I can get a 360 degree view from a hill about 400 metres across a road through our village. Potential problem is the road is a main north-south road in busy south-east England (A29) and traffic hares through day and night. A 79 year-old pushing a rocket launcher on a sack truck is an obstacle speedsters don't expect to encounter. I wear luminous bands and carry a white light forward and a red light behind, then I have to push the gear up the hill. You guys stowing your kit in cars - how portable is that? Observing at our place in France is easier - just wheel it out of the barn on a flat home-made trolley. That's where it's headed this Sunday to replace the 8" Dob already there. Anybody want to buy a used sack truck?
  11. Nice tip and thank you. Screwfix are cheaper but, as the adage goes, prevention is better than cure. The glove combination works for me - no bleeding fingers at all this winter. So I'll just carry on wimping.
  12. Yep. Much the same thing in appearance in LIDL for £8, a quarter of the price, but I'll bet yours last longer. Most of the replies to this post make me feel a complete wimp but if I don't wear gloves the skin on my knuckles cracks in the cold and it's pretty uncomfortable for days after. You can also wear thin screen-touch gloves (£4 for two pairs from Mountain Warehouse) underneath that keep your finger/thumb tips warm but still give you the "feel" for twiddling.
  13. Anyone starting out in mid-winter might find they need a pair of warm gloves that still let them manipulate the bits and bobs while using their equipment in the middle of a cold field. I was given a pair of Astro Gloves a couple of years ago but for less than a third of the price you can buy a similar pair in LIDL on one of their specials counters. Every little helps (sorry, wrong supermarket!).
  14. Relpet

    Choosing a dslr

    Recently I bought a s/h Canon 500D, body only, from Park Cameras in Burgess Hill. It was a model launched to rave reviews about 9 years ago but this one had a shutter count of only about 3,000. It is a model recommended for converting for AP, though I will leave that for a while. Camera is guaranteed for 6 months and came with a handbook. I bought the kit lens, also s/h, and a shutter release cable. It came with a charger and Canon battery but I since bought a Duracell spare battery which works well. Total cost about £250. I have used a Nikon before, on long loan from a cousin, so not entirely new to DSLR imaging through a telescope. Our home in England is about 12 miles west of Gatwick/Crawley so the sky is heavily light-polluted. I bought the camera principally to use at our second home in France where the skies are much more image friendly. However, for the OU Orion course which started on Monday students were required to take a picture of the Orion constellation using a DSLR on a tripod. The best of my pictures is shown. About 15 seconds at iso400 and about f4 - my first attempt at photographing the night sky just using a standard camera and lens and under very difficult conditions. Nearly all the stars you can see in the picture were invisible to the naked eye. Hope this helps.

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