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SimonR

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Everything posted by SimonR

  1. - info/advice Everyone is a beginner in some things and an old hand in others. Much of my knowledge was theoretical and I needed practical advice about an actual telescope. If I didn't ask any questions in SGL it was because they had been asked and answered before. There is so much collective experience here that I found the answers quickly and from many different perspectives. - choices/decisions If I lived in the country under dark skies I would have got a light bucket, but I don't. I realised that the solar system would be the primary target and deep sky an extra. I narrowed it down to a long refractor in the 4" to 5" range because I wanted something portable, robust, unfussy and I had an idea that its high contrast would help to cut through light pollution. - what TAL 100RS on an unmotorised EQ5 mount and some good quality but old fashioned eyepieces. - why It looked like the best optics on a sturdy mount for the money and it has received uniformly good reviews. I noticed that owners have a particularly warm affection for it. - result It is what I was looking for, the 5" version would have been nice but is hard to find and much more expensive. It's had a few outings and has yet to show its limits because seeing conditions have not been good enough. I have now found several Messier objects with it which surprised me given the conditions. It's a well made machine. The only thing I changed was the 6x30 finder which was too small to navigate by - I found myself using binoculars to find things - I replaced it with a 10x60 finder which is like having the binoculars built in.
  2. Eye relief is a fixed function of the design of the eyepiece and does not vary with focus. If you are long or short sighted you can adjust the focus to compensate, but you cannot do anything about astigmatism. If you wear glasses for long or short sight only then you can take them off if you find it more comfortable (as I do), but if you have astigmatism then you may need to keep them on and, if you do, then you will probably want to use an eyepiece design that has long eye relief. I have very slight astigmatism in my right eye, which is the one I tend to use, but I still prefer not to use glasses - it needs to be more than slight before it's a problem. The only hassle I have is taking my glasses on and off, and on and off... Simon Edit to add - people's tolerance of short eye relief is subjective and can depend on things like having long eye lashes that brush the lens.
  3. Well, it's a thumbs up for Planets, I'm going to start Galaxies tonight, bedtime reading.
  4. I don't know about similar - if you are travelling to a foreign land there's nothing wrong with a good guide book but it's not going to give you the depth that a history of the country might. Background reading is something else. I've just finished: Planets - A Very Short Introduction, by David A. Rothery. Here's my mini-review: Rothery is Senior Lecturer in the Open University Department of Earth & Environmental Studies and has been involved in various lunar and martian missions. In a bit over a hundred pages he describes the evolution of the solar system, the geology of the terrestrial planets, structure of the gas giants, satellites and rings, asteroids, trans-Neptunian objects and exo-planets. This is 'popular science' done right, while it doesn't assume much prior knowledge, it doesn't over-simplify or use misleading analogies either. It's from a series of books from the OUP written by experts for non-experts. For my next read I have copies of: Galaxies - A Very Short Introduction, John Gribbin Cosmology - A Very Short Introduction, Peter Coles I've only skimmed through these two as yet, I'll let you know what I think.
  5. One other possibility - if the cross hairs in the finder are off-centre they will move off-target if rotated. Just a thought, easy to check.
  6. Running Stellarium on a mac too. In the location window there is a huge alphabetical list of towns and cities, you may find yours or one nearby.
  7. Ouch. I had an Apple Mac stolen once, it turned up in 'Cash Converters' a few days later, have you got any serial numbers?
  8. I need to move up the coast a bit, I've heard about that sky in Norfolk. Only 5 from Ipswich.
  9. Or, put the tube on a level surface and set up a right angle on each side, a pair of carpenter's squares ideally, but anything with a reliable 90 degree corner will do, then measure between them. Like this _|O|_
  10. Hi. Yes, a pair of binoculars can go a long way, and I agree that part of the fun is the hunt. Simon
  11. I found M31 in Andromeda last night, the first DSO for my new scope. It was hard because it's a bit fuzzy and the sky was far from perfect. Starting with the familiar, I followed a route from Betelgeuse to Aldebaren to the Pleiades and then, about half way to Cassiopeia, Mirach. Short hops from there. It was hard to trace the route in the finder so I got my binoculars out and found were it should be, got a hint of something, and scanned the route again. Then I retraced the final steps with the scope, rechecking with the binoculars when I got lost. It took a few attempts but finally, there it was. So that's my tip, use binoculars to scout the area first.
  12. Thanks for finding that, it's a very tidy solution, much easier than a dovetail + clamp etc. But my existing finder has a custom mount which is not interchangeable with anything else. So this would still need to be mounted somewhere. It's a possibility but I may need a tube ring or two.
  13. I have a 6x30 straight-through finder on my telescope which is useful but there are times when a larger, right angle finder would be helpful. It would be a bit of a luxury on my setup and for that reason it's not a priority. But, I saw a nice one on ebay and put in a modest bid. To my surprise I now have it, it's a University Optics 10x60. The question is how to mount it best. It has a pair of three-point rings but I have to decide what to attach them to. There are several options: [1] On a dovetail bar/clamp fixed to the main tube. This will require quite a lot of hardware but it is quite elegant - the finder will rotate with the tube so it will always be in a usable position, and it will be easy to attach/detach. [2] On a pair of additional tube rings. A lower cost and perhaps more flexible version of [1] that won't require any drilling. [3] Directly on the existing tube rings. This is the easiest way, it will require little additional hardware, but the finder will not rotate with the tube. Obviously I don't want the finder to end up in an unusable position when I rotate the main tube. But if I do [3] and place the finder directly opposite the mount I think it may work out, and the weight of the finder will always be at a constant distance from the mount axis so the balance will not be upset if I rotate the telescope tube (not that this finder is particularly heavy, this may not be an issue). I'm leaning towards [2], or maybe [3]. I've googled this and come to no conclusion. Before I start drilling holes, any thoughts?
  14. I might facetube the second link, spread it around a bit.
  15. Ramsden [R], Huygens [H] and Kelners [K] are quite early designs, in the 20th Century they were largely overtaken by Orthoscopics [Or], Erfles [E] and then Plossls. There is an interesting (and I think down to earth) article here Eyepiece Review Pitfalls On another matter - are you sure that eyepiece is 65mm? Seems very long.
  16. I was going to say, 2mm eyepiece! On that scope it would give you a magnification of 450x which is insane. Even the 5mm is pushing it. The eyepiece you need is the one your reach for but don't find, and that depends on what you will be looking at. Experience will find it for you. I'd hazard a guess it might be a long one, but wait and see.
  17. Well, I don't know about downloadable although there's sure to be something out there. I like my copy of the Collins Gem - Stars book. It's pocket sized, I find the diagrams much clearer than most and the commentary is useful. Incidentally, the diagrams in the Collins are drawn by Wil Tirion, famous for the classic Sky Atlas 2000.0. [Edit to add - Not what you asked for, I know, but it's worth seeking out]
  18. Sounds like you had a great night. Sometimes you can't beat a pair of binoculars. While I was waiting for my scope to cool down tonight, I had a quick look around with my 7x50s and took in Orion and the Pleiades. By the time I had the scope sorted out the clouds had returned.
  19. I'm sure that's true. I intended the above as information without an opinion. [opinion starts] If you have a good Barlow then that's an option, but I can see the convenience of having it in a single optimised package. I try not to think too much about brands but there will be real differences in the degree and accuracy of the lens polishing and the quality of the coatings. [opinion ends]
  20. Just a bit of background, in theory; Eye relief diminishes as the focal length of the eye piece diminishes, this can become a problem much below perhaps 15mm. This is a particular problem with plossls because their eye relief is usually only 80% of their focal length. You can get around this by using a longer eye piece and Barlowing it so that it is effectively shorter. It will retain its original eye relief. We could take this further. Select a plossl with good eye relief, a 20mm perhaps with eye relief of around 16mm. Add a small specially designed Barlow to make it a 12mm. Now design another Barlow to make it 10mm, and so on: 8mm 7mm, 6mm... This is essentially what most 'planetary' eye pieces are - one of the basic designs such as a plossl, with a built in Barlow lens. If you ever see a range of eye pieces of differing focal length and they all have exactly the same eye relief this is what the manufacturer has done.
  21. Google does a fair job of translating it: Google Translate There is a note in the corner that is translated as "prepared for an exclusive personal use and educational (Thanks to the Author Antonin Rùkl)". So I guess it's OK for personal use only if he has given permission.
  22. Here's a map, not sure about the copyright on this, it looks like the Rukl Atlas; LINK - Atlante Lunare
  23. According to the weather map the whole country is under cloud. I blame the BBC. Let's hope there are no repeats on Dave...
  24. Yes, I suspect a motor of some sort will be appearing before too long. It's all very upgradable. Simon
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