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Everything posted by Alan64

  1. For budding astrophotographers on a budget, this kit would make for an very good start, and at the very minimum insofar as price and capability... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-130p-ds-eq3-pro-goto.html One will not get Hubble-quality images out of it, but they would be quite satisfactory nonetheless. It's rather odd that the 130P-DS is not offered and bundled with the non-motorised EQ3 equatorial, as the 150P-DS is; very odd. Perhaps someone will look into that oversight... The only other alternative is to purchase the two separately, but upping the ante with a sturdier EQ5-class equatorial... http://www.firstlightoptics.com/all-mounts-motors/skywatcher-eq5-deluxe.html http://www.firstlightoptics.com/reflectors/skywatcher-explorer-130p-ds-ota.html ...and for a combined total of £398. In future, after spending some time learning the workings of an equatorial and observing with the capable 130mm f/5 Newtonian, the existing kit may then be equipped with a go-to system featuring PEC and auto-guiding capability for astrophotography... http://www.firstlightoptics.com/skywatcher-mounts/synscan-pro-goto-version-3-upgrade-kit-for-eq5.html That said, I take the odd afocal photograph with a 150mm f/5 Newtonian coupled with a non-motorised alt-azimuth, and simply by holding a wee Canon S110 PowerShot up to the eyepiece...
  2. I've found that a collimation cap will be quite adequate at first. A passive, Cheshire collimator is helpful when adjusting the secondary mirror assembly, particularly if it's badly out of alignment. A laser collimator is never necessary, but perhaps desired when one scales up to Newtonian apertures of 200mm and above, and when one cannot look into the Cheshire and reach the primary adjustment screws at the back of the telescope simultaneously. Even then, laser collimators, the cheap ones especially, are known to need collimating in and of themselves, and before they can be used to collimate the telescope. Many have regretted the purchase of a budget laser collimator. Save your money. For the most part, they amount to nothing more than a gimmick. Why, one can easily reach the primary adjustment screws on this 150mm f/5 whilst peering into a collimation cap and a Cheshire, too... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-eq3-2.html Of course, that one would not be very portable, and more for the home; but it is considerably less expensive than the aforementioned alt-azimuth kit, and with the ability to motorise the RA(right ascension) axis for automatic, hands-free tracking. A 150mm f/5 isn't much larger than a 130mm f/5. Here's an image, yet another, of the 150mm f/5 optical tube with a standard salt shaker to illustrate the scale... Tuck it under one arm, and off you go. 150mm of aperture doesn't seem like much, and over that of a 130mm; that is, until you view a direct comparison... As you can see, there's a considerable increase in light-gathering area.
  3. I'd strongly suggest this kit instead... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-az4-mount.html True, it's not motorised, but the optical tube is of much better quality, and where it really counts in the end. It has a 2" focusser, and for the use of 2" eyepieces in future. The other has only a 1.25" focusser.
  4. I would imagine that you would be assisting your child in the use of any telescope. This would be great fun, with a tremendous wow-factor, and for the two of you... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-az4-mount.html I'm certain you could handle the maintenance aspect -- collimation -- when needed. I realise that it's a lot more than you perhaps intended, but it would show so much more than those previously suggested, and it would last for years to come. You could either hold your child up to the eyepiece; or get a safe step-stool for him to climb up, and thereby to reinforce the aspiration to reach towards the sky. In any event, never allow any child to use a telescope unattended, especially during the day when the sun is out.
  5. This would make for a fine choice, and well-balanced between observing within the solar system and beyond into deep space... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-az4-mount.html I have a similar kit myself... I've taken several afocal photographs with the kit, and simply by holding a camera up to the eyepiece... In future, and for the home, you can get a motorised equatorial, and still have the alt-azimuth for travel.
  6. http://www.firstlightoptics.com/reflectors/skywatcher-heritage-130p-flextube.html
  7. On this first page alone... http://agenaastro.com/telescopes/refractor-telescopes.html ...most every telescope has its focal-ratio listed within its respective thumbnail. One has to dig deeper, and into the specifications to find the focal-length. When beginners and "newbies" begin searching for a telescope, it's the focal-ratio that they see advertised, hence the title of this thread. Apertures that are considered by those first entering into our hallowed pasttime range from 60mm to 8"(200mm). Within the subset ranging from 4"(102mm) to 8"(200mm), knowing the focal-ratio alone is quite helpful in determining that which is capable of low-to-medium magnifications for deep-sky, and that which is capable of medium-to-high magnifications for lunar and planetary observations, and at a glance as one flits from one page, from one site, to another. However, it is recommended that beginners delve into the specifications once they zero in on a telescope or telescopes of keener interest, and for the focal-length in determining if the telescope would be best suited for the planned observing agenda. If one wants the odd look at the Moon or Saturn and, hopefully, at a not-quite-so-twinkling star, then a 4" f/10-f/15 would serve, and capably under light-polluted skies. Conversely, under much darker Texan skies, a 6" or 8" f/5-f/6 might be the ticket, and for observing beyond the solar system into deep space, along with satisfactory views of the solar system in addition. Some observe double and variable stars, exclusively, and may favour a 3" or 4" f/16 refractor. Others desire only to observe the Moon and the planets, and then might choose a 4" or 5" f/9-f/12 refractor. Still another prefers observing only galaxies, nothing more, and picks a 12" f/4-f/5 Newtonian for the task. Then, to complicate matters, there's the budget. Beginners are generally reluctant or unable to sink a lot of cash into a first telescope, but they want their money's worth, and yes, "the best bang for the buck", hence... "May I interest you in an 8" f/6 Dobsonian, sir?"
  8. Focal ratio is nonetheless a determinant among like-apertured telescopes.
  9. If you desire a good balance between higher-power observing within the solar system and wider, lower-power deep space observations, then an 8" f/5 or f/6 Newtonian will come closest to observing both; the gamut; a little of this and a little of that; and whilst favouring neither, especially in the case of an 8" f/6 Dobsonian. I personally chose an 8" f/5 Newtonian as my "light bucket", and to lean slightly more towards wide-field deep-sky observations. The focal ratio of a telescope, whether "slow" or "fast", most certainly has everything to do with observing, and through a static eyepiece. Consider... An 8" f/10 Schmidt-Cassegrain has a focal length of 2032mm, whilst an 8" f/5 Newtonian has a focal length of only 1000mm. Insert a 15mm into either and you get magnifications of... 8" f/10: 135x, and ideal for lunar and planetary observations. A 32mm ocular would result in a magnification of 64x; a bit high-powered for wide-field deep-sky. 8" f/5: 67x, and suited for general purpose observations of both the solar system and deep space. A 32mm would offer 31x; slightly high in my opinion, but still an ideal per its 8" aperture for deep-sky, and for scanning the star-fields of the Milky Way even. If you want higher power for viewing the shadow-transits of Jupiter's moons across the face of the planet, or a close-up of a lunar crater, then combine a 2x barlow with a 9mm eyepiece, and for a simulated 4.5mm: 222x. Hence, the overall versatility of an f/5.
  10. Insofar as an "all-around" telescope, and for visual observations of the gamut, that is, within the solar system and beyond into deep space, I have found that an f/5 telescope combined with appreciable aperture is the closest to "having your cake and eating it, too"; a 6 f/5 or an 8 f/5, regardless of design, specifically. Such are the fulcrum, with all others positioned variably towards either extreme, and as trade-offs in one or more aspects.
  11. Is an f/5 really that bad? http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html The format performs quite well, and is well-balanced between deep-sky and planetary observations... In light of the winds, I'd go with an f/5, unless you're really wanting a planetary reflector.
  12. The Orion is equipped for astronomical use with its 90° star diagonal, whilst the Sky-Watcher is equipped for daytime/terrestrial use with its 45° Amici diagonal. If you don't need the two eyepieces included with the Orion, then go with the Sky-Watcher. You can get a 90° diagonal for nighttime use in future. Both are identical otherwise... http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&mobile=1&pm=1&ds=0&item=111705513945
  13. Betelgeuse and Aldebaran were splendid through the 12mm Konig II and the new Antares 2x barlow; as wee, blazing, fiery suns they appeared, and noticeably orange in colour. As usual, the camera couldn't capture the fine details... I was half-hoping for a nova right then and there, then to record it for posterity.
  14. ...at last, and the first in over a fortnight. Looking eastward... Two afocal views of the Andromeda galaxy via the 150mm f/5 Newtonian and the 40mm Plossl... ...alas, only the core. Would that my 200mm f/5 was completed; although I do have my doubts as to it being that much more of an improvement over the 150mm.
  15. It might very well be less expensive to order a kit from outside of India, and not necessarily an Orion-branded. I realise that there may be duties to pay, but still. Also, in getting a kit with electronics and motors, will there be a repair facility there in India in the event of failure? The telescopes are manufactured just to the north in China. Have you checked to see if any vendors there carry a similar kit?
  16. Saswata, In my experience, I've come to find that the 6" f/5 Newtonian is a GREAT all-around telescope; well-balanced between observing within the solar system(the Moon and planets), and also beyond into deep space(galaxies, nebulae, star clusters). Its only drawback is that it's not suitable for daytime use, except for solar-observing. Personally, I do not consider that a drawback given its many advantages. Orion offers a push-to 6" f/5. It doesn't have motors(which can be a good thing), but it does have a computerised push-to system whereby one simply pushes the telescope whilst noting the object's coordinates displayed on the hand-held controller. It's a go-to of sorts, but without motors... http://www.telescope.com/Telescopes/Dobsonian-Telescopes/IntelliScope-Dobsonians/Orion-StarBlast-6i-IntelliScope-Reflector-Telescope/pc/1/c/12/sc/27/p/102026.uts?refineByCategoryId=27 It's compact, but a bit heavy, for me anyway. It weighs a total of 23.5 lbs(10.7 kg). I'm seeing dark sites not too terribly far from Kolkata... http://static.ibnlive.in.com/pix/slideshow/12-2012/how-indian-cities/india.jpg It is under dark skies that the 6" f/5 would come into its own, and excel.
  17. This kit would be more dependable, durable, versatile and less expensive. The GSO 150mm f/5 Newtonian OTA is superior to Orion's. Also, the mount will accept most any telescope up to 150mm in aperture, including a 60-80mm refractor or spotting scope for daytime use that might be purchased in future... http://www.teleskop-express.de/shop/product_info.php/language/en/info/p26 http://www.teleskop-express.de/shop/product_info.php/info/p8069_TS-Altazimuth-Mount-with-Fine-Adjustment-and-Quick-Release.html http://www.teleskop-express.de/shop/product_info.php/info/p167_TS-1-25--Cheshire-collimat-ng-eyepiece-for-refractors-and-newtonians---metal-tube.html Teleskop Service ships to India, and at very reasonable prices given the distance.
  18. Saswata, Are you planning on purchasing a telescope from the U.S.?
  19. If I'm not mistaken, all fast Newtonians possess a parabolic primary. With Newtonians of longer focal-ratios in the smaller apertures, my understanding has always been that sphericals have been provided instead. A favourable review... http://www.amazon.co.uk/review/R235S5WBP122AW/ref=cm_cr_dp_title?ie=UTF8&ASIN=B000LJSL88&channel=detail-glance&nodeID=560834&store=photo You'll want at least a collimation cap... http://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html ...if not a Cheshire in addition... http://www.firstlightoptics.com/other-collimation-tools/cheshire-collimating-eyepiece.html
  20. For me, August was delightful due to a drought, albeit with some mosquitoes still. Said conditions drifted into September a bit, but then occasional showers began picking up their pace, although with ample observing nights until recently. Now, here in Novemeber, I've only seen a relatively clear sky for about an hour in the last two weeks. I've always despised rain; the mud and muck in particular.
  21. Hello Saswata, The first and third look to be identical, and both for the same price as well. The second has an alt-azimuth mount, and of a design that I have never seen before. Out of those three, I'd go with the third, the Sky-Watcher, but I have to wonder if Synta manufactured it... I have a 150mm f/5, and it's a great performer... There is one thing however. I don't think you'd be able to use it as a terrestrial/daytime 'scope due to the upside-down image that it would present. Otherwise, if made well, and with a parabolic primary mirror, it would provide very good to excellent views of the night sky. With a SAFE solar filter, it could also be used to observe the sun.
  22. It's nice to see Orion Optics' opticians making Sir Issac proud.
  23. I was carrying this kit around and about the land one night, an Orion "StarBlast 6"... The next day I was miserable, with muscular straining of the abdomen. I recovered after a full day, but no more of that as I then placed the optical tube on a more-manageable, traditional alt-azimuth... I now find that the telescope is even easier to use.
  24. A 12" Newtonian will indeed keep you busy for years to come; decades even. Just be certain to wear an elastic back-brace, from Home Depot or Lowe's, when moving it around and about. Here's an interesting comparison between apertures... http://www.obsessiontelescopes.com/graphics/global/M13_comparison_760px_PNG.png
  25. Thank you, and you're very welcome. I strongly recommend that you do not purchase anything until you have researched further, and to the core. That is most important, whether it takes weeks or months even. Do not be in a hurry, for haste is the enemy in this endeavour. To continue, this is the option for an equatorial to begin imaging, and comes equipped with an autoguider port for guiding during longer camera exposures... http://www.bhphotovideo.com/c/search?N=11124463&InitialSearch=yes&sts=pi The aforementioned CG-4 bundled with the Newtonian is an EQ3-class equatorial, and with a load-rating of approximately 20 lbs. The Exos-2GT is an EQ5-class, and consequently larger and heavier, with a greater load capacity, and necessary to carry not only a telescope but your camera and other accessories without overloading and binding the mount. Therefore a telescope of lighter weight must be stressed. Remember, for instance, if a mount has a 30 lb. load-rating, then your telescope, camera and other accessories necessary for AP must not weigh more than 50-60% of the total load-rating; that is, 18 lbs. Else, the motors will be strained, the mount's gears may bind or strip out, tracking errors would abound, etc. The Exos-2GT is rated for 30 lbs., but for visual use only(18 lbs. max for AP) and is also equipped with go-to technology, for visual use, and also for zeroing in onto objects of interest for the taking of pictures. With the go-to system, one simply enters the desired object to view using the hand controller, and the telescope then slews to its intended target, and hopefully positions the object in the center of the eyepiece when it stops slewing and begins to track. Here's a demonstration of an EQ5-class equatorial with go-to... Now, the telescope itself within the video is a large 8" f/5 Newtonian, and at the mount's extreme limit in handling, for visual use only. For AP, again, the entire load must not exceed a little over half of a mount's load capacity. You may see recommendations for another EQ5-class equatorial, the Celestron Advanced VX, or AVX. It's $220 more than the Bresser Exos-2GT however, and though it comes with an extra feature or two for AP, the AVX's declination axis is known to stick, and due to a simple flat washer used as its bearing. Both axes of the Bresser Exos-2GT utilise ball or roller bearings, for right ascension and declination, and for smoother operation. Astrophotgraphy is quite the other animal in its own right, and when compared to visual observing. Whilst collecting that ancient light from a distant galaxy, a camera must be held in place firmly, and in order to track the galaxy, or any other object, without blurring the resulting image. Also, the mount must track an object steadily and precisely, over a span of several minutes, and also without blurring the final image. Here's an even larger, and more capable EQ6-class equatorial in action, and fully equipped for astrophotgraphy... https://www.youtube.com/watch?v=uJNjvtpjQvk
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