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azrabella

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Posts posted by azrabella

  1. I have no trouble with  collimation, and have my scope outside at all times. So no issues with thermal equilibrium. Of course I cannot do anything about the state of the atmosphere, but we are drifting from my original query. I'll be more precise - would there be any practical benefit to me buying a 7mm Nirvana eyepiece over using a 16mm Nirvana with a telecentric amplifier on a 150mm f/1200 Dob?

  2. Well, it seems that my optical choice is perhaps so far the best I could have made, thus far. I think I'll go for the 7mm Nirvana 82 degree (x150) as that will give me the widest field/longest drift time, I guess. It surely must yield a somewhat brighter image than barlowing the 16mm as presumably less glass in the optical path?

  3. Hello folks. I currently own just one scope - namely a 150mm f/1200 Dobsonian with a very good set of mirrors, and use it in less than pristine skies. My main interest is double stars but have not really used eyepieces shorter than 9mm. I did try a BST Starguider 8mm but found it far too soft to offer any advantage. Perhaps my most often used eyepice is the 16mm Nirvana ( barlowed) and that seems to work ok. I can comfortably discern a roughly equal pair of stars down to about 1.0" which is probably approaching the scope's theoretical limit. I have a hankering for the 7mm version of the Nirvana (there is currently nothing in between) but am on a tight budget and worry that the 7mm might be a step too far, given the scope being used. If anyone has any advice or opinions on this, I would appreciate it very much.

    Thanks in advance.

     

  4. Hi John,

    It probably is the same eyepiece, but reasonably seems to suit my eyes for it's intended purpose as a wide field finder with a little more magnification and slightly more contrast than my 30mm Aero. As said in another post, it's down to the individual's own eye/scope combo. I must stop chasing the ever diminishing return vs ever increasing cost of eyepieces.

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  5. I finally had the opportunity to test the newly arrived Fullerscopes 20mm 82 Degree eyepiece barlowed using an ES 2x tele extender which gave me an effective wide angled 10mm. I compared it directly with a Baader MkIV at 12mm - only difference was the markedly larger fov with the Fullerscopes eyepiece.  I then tried the same thing with the Nirvana 16mm, again reducing down to an effective 8mm. No discernible difference. It seems that I now have a redundant Baader zoom eyepiece, plus I've saved money by not having to purchase a 12mm UWA.

  6. I don't much care for short eye relief oculars and have tried an ES 11mm, but didn't much like jamming my eyeball up close. I also have a 16mm Nirvana which barlows well to the equivalent of 8mm, so maybe I have the answer already. I have just purchased an old Fullerscopes 20mm 82 degree eyepiece. Perhaps the best, and cheapest, option might be so see how that barlows before splashing the cash... I'm always open to ideas though.

  7. I am looking for some help from you good folk regarding a choice of a mid price 12mm (ish) UWA (82 degrees + or -) eyepiece to be used with an f/8 Dob. I have a maximum budget of around £100. Am I asking for too much for so little? Currently using a BST 60 degree ocular, but would like a larger fov. Any suggestions much appreciated.

  8. Looking for a 26-32mm 2" 70 degree fov eyepiece and am confused by the plethora of generics out there. Initially interested in a Panaview, but on seeing very similar spec eyepieces I am wondering if they are not all coming out of the same factory. Prices sem to be reasonably consistant but how about quality? So now I am somewhat confused. Most, it seems, say something like SWA 70° 26mm - see below, but do not mention brand. Any advice on this.

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  9. I recently purchased and am eagerly awaiting arrival of a new to me (used) 17mm eyepiece that the seller (though not the user) informs me was Skywatcher's first foray into wide-angle eyepieces from c2003. It appears to have a dual fit format with a 70 degree fov, with the same configuration as a Meade 4000 Smoothside? I cannot find any reference on t'interweb, and was wondering if any of you clever slueths could identify it for me. Also if it is dual fit, then in 1.25" mode what happens to the fov, or is the inner barrel removable??? I don't have a clue. Images supplied.

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  10. I'm thinking of doing some visual (white light) solar astronomy with either an ST80 or a 150mm Dob. Thing is, would it be better to use a Baader Solar filter across the full aperture of either or use the offset 50mm aperture built into the caps of these scopes. Is there any advantage/disadvantage either way apart from the cost involved?

  11. Interested in a diagonal for my f/5 richest field refractor and am not sure of the issues with using a mirror vs prism diagonal. Some say that for fast scopes a mirror is best, while others say that faster than about f/7 though, the prism will induce spherochromatism. Does this apply more to a doublet (non apo) refractor, or is the difference negligible at relatively low power? I intend using the scope for comet patrol and ideally require orientation to be as per binocular view.

  12. Neil English

    Chronicling the Golden Age of Astronomy

    A History of Visual Observing from Harriot to Moore

      Hardcover: 665 pages

      Publisher: Springer International Publishing AG; 1st ed. 2018 edition (13 Nov. 2018)

      Language: English

      ISBN-10: 3319977067

      ISBN-13: 978-3319977065

      Product Dimensions: 15.5 x 23.5 cm

    A personal review

    From the outset I should mention that this is a massive tour de force, some 665 pages, profusely illustrated throughout, covering the history of observational astronomy and perhaps more importantly the   pioneer astronomers themselves. Whilst the chapters (all 41 of them) are laid out in chronological sequence for good reason, the sections can equally be read as standalone mini-biographies. The list includes some names that are familiar, from Galileo through to the Herschels, Charles Messier, Friedrich Bessel, Thomas Webb, John Dobson, democratiser of sidewalk astronomy in the 1960’s, and famously, the late Patrick Moore. There are many others who might not be so well known such as Clyde Tombaugh, the discoverer of Pluto. Will Hay, better known as a British comedy film actor of the 1930’s and 1940’s. George Alcock, comet and nova discoverer. David Levy, another of the great comet hunters. All did their finest work as amateurs, all totally dedicated to the pursuit of their hobby.

    The author, himself an enthusiastic amateur astronomer, has a way of making history come alive. He has written with passion something that is both unique in substance and enjoyable in style. It is crammed with “I didn’t know that” facts as well as a most studious and very thorough account of an area rarely, if ever, covered in such depth – that is, the great visual astronomers and their contributions to our understanding of the Universe.

    The often-used phrase “necessity is the mother of invention” becomes obvious as we learn how, incrementally, the optical telescope developed from a pre-Galilean spyglass to the unwieldy “arial “ refractor devices of the 17th century, some of which were literally hundreds of feet in length, to the development of lighter and easier to make mirrors rather than ever heavier and therefore more expensive lenses leading to the folded optics of the Newtonian type reflector, modern versions of which are still favored by today’s astronomers. Chapter by chapter the fascinating story unfolds, allowing us an insight into the ingenious ways that these pioneers dedicated their lives to the advancement of visual astronomy through trial and error, constantly struggling with sometimes huge financial cost and quite often with their health. This is their legacy, because when it comes down to it – the telescope is still the fundamental instrument of astronomy. It is the eye on the sky.

    The latter part of the book is often punctuated by the author’s own visual comparisons of some of the subjects under discussion - very useful for anyone wishing to see for themselves what the original discoverers were viewing. Where possible he uses telescopes of similar size and type thereby helping to accurately recreate some historic observations.

    Neil English used the phrase “Grand Amateurs” and I think that just about sums up this book. Highly recommended.

     

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