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Ruud

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Everything posted by Ruud

  1. A wonderful sketch, Mike. Thanks for sharing!
  2. Awesome sunspots and some wonderful sketches! Thanks for sharing.
  3. Ruud

    Orion Nebula

    That's a lovely sketch!
  4. Ooh! Amazing! With poetry! Do you know The Little Fete by Vangelis? Listen to it here. It is quire beautiful: / Ouça aqui. É muito bonito: https://www.youtube.com/watch?v=sJa2yup0SqY The Little Fete I take a bottle of wine and I go drink it Among the flowers, we are always three Counting my shadow and my friend The shimmering moon Happily the moon knows nothing of drinking And my shadow is never thirsty, when I sing The moon listens to me in silence When I dance, my shadow dances too After all festivities the guests must depart This sadness I do not know When I go home, the moon goes with me And my shadow follows me In Portuguese: A pequena festa Eu pego uma garrafa de vinho e vou beber Entre as flores somos sempre três Contando minha sombra e meu amigo A lua cintilante Felizmente a lua não sabe beber E minha sombra nunca tem sede, quando eu canto A lua me escuta em silêncio Quando eu danço, minha sombra dança também Depois de todas as festividades os convidados devem partir Essa tristeza eu não sei Quando eu vou para casa, a lua vai comigo E minha sombra me segue
  5. Oh, new images. They are excellent! Good that you are posting again.
  6. Hi Jim, thanks for joining!
  7. Better buy her one like this: https://www.firstlightoptics.com/beginner-telescopes/skywatcher-skyliner-150p-dobsonian.html It is a bit over budget, but excellent for visual observation of the Moon and planets, and it will show her dozens of deep sky objects too. A wonderful all-round telescope that will keep her interested for years.
  8. Wow, congrats. It's almost bigger than your kettle! Happy observing.
  9. Excellent picture. Very clear. 10x wins: The eyepieces of the 10x do have better anti reflection coatings. This is obvious from your picture.. 10x wins: The EPs of the 10x have an apparent field of view of 65° compared to the 52.5° of the 7x. 7x wins: The true field of the 7x is 15% wider than that of the 10x. 10x wins: The 10x has a better exit pupil for astronomy. 5mm keeps a light polluted sky a bit darker and is more future proof (5mm makes more sense for when one gets older). Tie: Both show their best views when you keep them stable them on a bean bag, monopod or tripod. These are just my ideas of course. The 7x50 is no doubt an excellent instrument, but the 10x probably is a better choice. You are fortunate to have both. Congrats! Please compare them in the field, and share your experiences with us. We'd be very interested!
  10. Ruud

    Hello again !

    Hi Chris, I've only been a member for six years, so haven't yet had the pleasure to meet you. It's an honour to make your acquaintance, and don't you dare abandon us again!
  11. Astronomy, a textbook from Openstax: https://openstax.org/details/books/astronomy The book begins with relevant scientific fundamentals and progresses through an exploration of the solar system, stars, galaxies, and cosmology. The Astronomy textbook builds student understanding through the use of relevant analogies, clear and non-technical explanations, and rich illustrations. Well over a thousand pages. A good introduction to the many fields of astronomy. This book is free.
  12. First I need to set something right: I never answered to OP's original question. I would choose the Delos 14. That's the only one of the three for which I've never seen any drawbacks reported. For other focal lengths than the 14mm I'm very fond of the Morpheus line (I have the 4.5, 6.5 and 17.5mm). ---- Indeed, the exit pupil is not an image of the sky. It is a projection though, of the objective. Use a long focal length eyepiece, stick a heart to the objective, place your eye half a metre or so behind the eyepiece, and you'll see the heart on the exit pupil as well. Sure you can! Every one who wants to use my animations can do so. This would be an honour. The more people who see the animations the better. I have just one request: For use here please credit them to Ruud and for use elsewhere to Ruud, stargazerslounge.com Don, did you spot these that explain the difference between blackouts and kidney bean shadows? Plenty members here found them useful. I made a still to show how to recognise kidney beaning I normally include vignetting because it kind of belongs to the same family
  13. In this price range it is important that you buy from a place that has a good return policy, or go to a brick and mortar store where you can try before you buy. QC will be up to you. Prepare yourself for that and read up on how to test binoculars.
  14. Ruud

    Crater Peary

    Very detailed! That's wonderful.
  15. Here is an animation for both exit pupil and eye relief. Parallel bundles of light are focused onto a point in the objective's focal plane. Here an image is formed. The eyepiece turns this image into parallel bundles again. The eye focuses on the bundle and brings the light to a point on the retina. Objective and eyepiece together make the bundles narrower and increase their angle with the optical axis. This way they increase the amount of light that can enter the observer's pupil and provide magnification. Ideally, after leaving the eyepiece the light bundles all pass through a well defined zone. This is the exit pupil: the place where the observer should position his own pupil. The distance from the exit pupil to the objective is the eye relief.
  16. Yes, that happens with long eye relief eyepieces. Some people find it difficult to keep their eye centred on the exit pupil. Tactile feedback from a long enough eye cup usually helps. Still, I think an eyepiece like the RKE should be priced under £50. It is after all a simple three element 45° design. But it still is an appealing eyepiece! Maybe you can find one on the used market.
  17. It is a magnificent sketch, Mike. Thanks ever so much for sharing!
  18. The floating effect comes from the tapered top of the housing. The 28mm RKE has a lot of eye relief, and from the proper viewing distance you only see a slim rim of housing because you are looking alongside the sloping top. So the image fills the eye lens while the eye lens seems to hang in front of you, almost as if not supported at all. This effect is not unique to the 28mm RKE. When you use a Morpheus without eye cup you get a similar illusion. Should you use the 28mm RKE with an eye cup, I'm sure the floating image effect would disappear. I was amazed of the image quality the 28mm RKE delivers in the f/4.2 Edmund Asroscan. Being only a three element design the Rank Kellner design ought to be a very popular budget eyepiece. Unfortunately, the price for a 28mm RKE is $85.
  19. Don't buy a kit - they are a waste of money. A good budget range are the BST Starguiders. These are 60° eyepieces that cost under £50. For an 82° view you should look at the Nirvanas. They are enormous value: https://www.firstlightoptics.com/ovl-eyepieces/ovl-nirvana-es-uwa-82-ultrawide-eyepieces.html .The 4mm Nirvana will magnify too much. The highest magnification the C5 can handle with any grace is from a 5mm eyepiece. The C5 will show it's best views when used with eyepieces in the 10mm .. 32mm range. Personally I'd get eyepieces from this range and use a 2x Barlow for if I want higher magnifications. For the widest possible true field of view in the C5 you should consider a GSO 32mm Plössl (52°). An equally wide true field is obtained from a 24mm 68° eyepiece, but at a higher price.
  20. I have this one, but it might be too small for all you want to pack. It's big enough for me though and quite inexpensive, so I thought I'd mention it anyway.
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