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Andymarrison

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Everything posted by Andymarrison

  1. Nice. I reckon there must be someone in the US with one of these, or its "baby" cousins, clocking in at a measly 36" and 40".
  2. This whole pit idea is really growing on me. These guys look like they could do a good job - if they could make it a bit wider I reckon I could fit a Dob in there along with the wine... http://www.spiralcellars.co.uk/gallery-seventeen/
  3. I really like the idea of digging a big pit in the garden...I think I'll mention the idea just to see the reaction! If I don't post for a while you'll know why - my other half will have dug the pit and I'll be in it!
  4. I was a bit disappointed with the Horizon programme, too. I didn't think they had the balance quite right between the nice graphics and locations and the hard scientific content. I remember when I was a kid seeing Carl Sagan deliver the Royal Institution Christmas Lectures without any of the fancy visuals we have nowadays, and I was spellbound. Not sure we have an equivalent nowadays who can convey the wonder of the subject so convincingly and with so much obvious passion. Prof Cox does it for lots of people, I guess, and Marcus du Sautoy for Maths.
  5. Yes it is complete pants at the moment, and dangerous too because I'm spending a lot more time looking at Astro kit on the internet...
  6. I've only just convinced my wife that an 8" SCT can be stored in the house without it getting in the way. Can't see a 50" primary mirror being very popular.
  7. Does anyone have one of these?! Are these people serious?! Still, the Euromillions has rolled-over again this week... http://www.widescreen-centre.co.uk/Products/Orion_USA_50_Monster_Dobsonia.html
  8. Hello Terry - I'm also rediscovering astronomy after a long absence and it's a real pleasure to get involved again. Can't think of many better ways to spend one's retirement! Welcome to SGL!
  9. Andymarrison

    Hello

    Hello Steve, welcome to SGL. Sounds like you are in a great place to do astronomy.
  10. Andymarrison

    Hello!

    Hello Tony, welcome to SGL. Where did you get your Astro degree from? I did one 23 years ago and now I'm a tax accountant - don't let the same thing happen to you!!
  11. Hello Jim and welcome to SGL. I guess you have some nice dark skies in Norway to make the rest of us jealous?!
  12. Thanks chaps - 15mm TS-branded eyepiece now on order from Amazon.
  13. Does anyone know if the 12mm TS optics branded ED lens here on Amazon: http://www.amazon.co.uk/Flat-field-eyepiece-60°-NED12/dp/B0055BLUHG/ref=sr_1_75?ie=UTF8&qid=1338888477&sr=8-75 is the same as the 12mm BST Explorer? It certainly looks very similar. Someone kindly gave me an amazon voucher for my birthday, and it's burning a hole in my pocket...
  14. Congrats on the 925 - I couldn't stretch to the 925 so got the 800 instead, but I'm really happy with it so far (only had it a couple of months). What's the advantage of the Crayford focuser? I'm very new to this stuff, but am keen to learn!
  15. I think that the exit pupil is the focal length of the eyepiece divided by the f-number of the scope (f5 for your 200mm aperture scope with a 1000mm focal length). This means that the exit pupil would have gone from 1mm with your 5mm eyepiece to 0.5mm with a 2x Barlow (which effectively halves the focal length of the eyepiece) As far as I understand it the maximum usable magnification usually quoted is related to the smallest exit pupil reckoned to be practical - the usual rule of thumb for magnification is based on an exit pupil of 0.5mm, or put the more usual way 2xmagnification per mm of scope aperture (since exit pupil is also equal to scope aperture divided by magnification). Sounds like your practical experience bears out the rule of thumb that 0.5mm of exit pupil is about as low as you can go.
  16. Thanks everyone - sounds like it's a good buy. I'll let you know how I get on with it when it arrives!
  17. Does anyone have any experience of the Revelation Astro 2" 2x Barlow? Is it a good one, and are there any comparable or better Barlows at about the same price from other manufacturers? I'm a fan of compression rings, so I'm ruling out the Tal because I understand it isn't a compression ring type system. Thanks!
  18. Sorry if I'm going a bit too far "off piste" but I don't seem to be able to private message in response to Fandango's question about light. The stretching of the wavelength oiSight mentioned above is in fact because the universe is expanding - this means that space time is itself stretching, and light travelling from far away gets "stretched" with it, which changes its colour. However, even if the universe were not to expand, far away objects would still look much dimmer than close ones. There would be no stretching of wavelength any more, but the energy in the light from a star (or the reflected starlight from a planet) gets spread out over a bigger area the further it has to travel - this is just like the ripples from a pebble thrown into a pond - all of the energy from the splash is at first concentrated in a wave very close to where the pebble hit the water, but as the wave travels outwards the energy gets spread over a larger circular ripple. A leaf on the pond close to the splash would feel a large percentage of the energy from the wave, but the same leaf further out would see a much smaller fraction of the larger ripple, and so would feel much less of the energy of the original splash. It's the same with us looking at the light waves from a star - the closer we are the bigger the fraction of the star's energy that enters our eye (or scope), and the brighter it seems. In fact the energy per second hitting our eyes here on earth decreases with the square of the distance of the star - if there are two identical stars and one is twice as far away as the other, then the energy per second we see from the nearer one is four times larger (two squared) than what we receive from the farther one. Light is very interesting stuff (and doesn't always behave like a wave)! Hope that helps - sorry it's such a long post and apologies for going off topic again.
  19. Thanks - I think I heard that the Abingdon Astro Soc observe at Britwell Salome, so that definitely sounds worth a try. Seems a long way from New York to Britwell Salome, though - you must be a very dedicated observer!
  20. Does anyone know of any dark sky sites near the Berkshire/Oxfordshire border? Have had a look on the Dark Sky Discovery site, but the whole area looks remarkably blank!
  21. Globulars are right at the top of my list too after a few clear nights (at last!) with my first scope - hadn't expected them to be such a beautiful sight (had my heart set on galaxies) until I saw M3, and then after that M13 - wow! The only thing that's up there in wow factor so far for me is my first view of Saturn through a scope a week or so ago - majestic.
  22. Thanks John - I'll follow your advice and use in 1.25 mode.
  23. I think I get it now. Because I only have one eyepiece, namely the 24mm Hyperion with no lens group in the 1.25" barrel, I had just assumed that to use the Hyperion eyepieces in a 2" star diagonal, I would remove the low er section (which of course has no effect in the case of my 24mm). However, it seems that with anything other than the 24mm I should be dropping the entire assembly into the 2" dagonal (with 1.25" lower section and its lens group still attached). Sorry for all the dumb questions.
  24. Sorry John - took a while to sink in that this was the case with the entire range i.e that this happens with all of the Hyperions.
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