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Alan64

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Everything posted by Alan64

  1. Yes, it would work with a smaller telescope; fancy that. The Meade's was a bit larger, but of the same design, incidentally.
  2. It seems that manufacturers possess the inexplicable notion that an equatorial is best for beginners, and thereby proliferating and inundating the market with the EQ-2 as an all-around mount. Of course, the AZ-3 is much worse... http://ca.skywatcher.com/upfiles/en_mounts_caty01317065198.jpg ...so much so that I'd rather have the EQ2 and wing it. I had one very similar to the AZ3, and loathed it, and for a very brief time before I sent it and its defective Meade 390 refractor packing. The kit was brand-new. The 90mm refractor's doublet appeared as though it had fallen out of its cell into gritty, damp dirt, then placed back into its cell. I had never seen anything like it. As a result, to this day I own not a single Meade product. First impressions are important. I once had a Japanese-made version of the EQ2, and for a Parks 80mm f//11 refractor, and that which replaced the defective Meade and its mount, and I liked it a lot... http://www.astromart.com/images/classifieds/370000-370999/370322-1.jpg I gave it to a close relative over ten years ago, and I don't believe he has used it even once. I wish I had it back.
  3. Between these two in question... http://www.firstlightoptics.com/beginner-telescopes/skywatcher-explorer-130p.html http://www.firstlightoptics.com/reflectors/skywatcher-explorer-130.html The 130mm/5" f/7 has a longer focal-length, than that of the 130mm/5" f/5, and therefore a longer optical tube. 900mm for the f/7...650mm for the f/5. Take a low-power 30mm eyepiece, for instance. With the f/7, the magnification would be 30x; with the f/5: 22x. A 30-32mm eyepiece helps to serve as a "finder", there in the sky. A larger portion of the sky would be visible with the f/5. After a search, and an object of interest is spotted, one may then pop into place a high-power 9mm eyepiece: f/7(100x); f/5( 72x), and for a closer inspection. The f/7 is somewhat better at higher powers, whilst an f/5 is somewhat better for lower powers. Both telescopes, however, are equipped with same mount. With the longer tube of the 130mm f/7, there is an increase in the "moment-arm" effect; a flexing of the tube, particularly in the wind. The tube would therefore be more "shaky", for the lack of a better word, unstable, and therefore more difficult with which to observe, especially at higher magnifications. The 130mm f/5 would be nonetheless more stable upon the EQ-2 mount. As a bonus, with the 130mm f/5, you get a parabolic primary mirror. The Heritage 130P also comes with a parabola, but I'd prefer a solid-tube myself. That said, with the equatorial, the telescope can follow and track any object there in the sky; and if the RA axis is motorised in future, the tracking would be automatic, with an object practically motionless there in the eyepiece, standing still, for long-term observing, and without having to touch the telescope or the mount. The telescope demonstrated within this video is the shorter, parabolic f/5 variant... In future still, if a simpler alt-azimuth mount is desired, the tube can easily be transferred to it... http://www.rothervalleyoptics.co.uk/skywatcher-az4-1-alt-az-mount-with-aluminium-tripod.html Keep in mind that with the 130mm f/5 on the EQ2, you won't be paying as much for the mount as you will be for the optical tube itself. The Newtonian is of very good quality; and, if cared for, will last for many years. Whilst Jupiter and its moons are a sight in and of themselves, Saturn, its "father", with its imposing ring system and its largest moon, Titan, is even more wondrous, and should reappear well into the night sky sometime in the spring. I enjoyed observing Saturn last late-summer and fall, and with my 150mm f/5 on a traditional alt-azimuth mount... Great fun, that was!
  4. A rack can easily be made with 1/4"-thick oak, metal L-brackets, and a 2" hole saw, the latter usable even with a hand-drill.
  5. Hello Positron, and welcome, If you're looking for a 150mm f/5 Newtonian, you'll want one with a four-vane spider assembly, like this one... This is my Orion(USA) 6" f/5 Newtonian. It was made by Suzhou Synta Optical Technology Co., Ltd. of Suzhou, Jiangsu, China. The company manufactures astronomical equipment for Celestron, Orion and Sky-Watcher... The curved or bowl-shaped surface of the primary or main mirror, located at the back, has a special type of curve known as a parabola. The other type of mirror used in Newtonians is a spherical. You want one with a parabola instead... http://www.acoustics.salford.ac.uk/feschools/waves/pics/curvedmirrors.jpg A fast Newtonian's parabolic mirror produces sharper images. Parabolic mirrors are more difficult to figure, and therefore more expensive to make, but that's the kind you want. The one within mine is parabolic... It should be center-dotted, with a white "doughnut", as seen in the center of the mirror. This is a Meade 6" f/5 Newtonian... http://images1.opticsplanet.com/755-405-ffffff/opplanet-meade-lx70-r6-6in-newt-ref-tele-optical-tube-asm-270021-main.jpg It's of very good quality, too, and is also made in China. Try to find one within one of those brand-names(Celestron, Orion, Sky-Watcher or Meade), and you can't go wrong. If you're wanting an alt-azimuth mount, too, then here are some examples of said mounts that will support said telescope... http://www.bintel.com.au/Mounts---Tripods/Alt-Az-Mounts/Bintel-SkyView-Alt-Az-Mount/98/productview.aspx 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/p4539_TS-AZ5-Alt-azimuthal-Mount-with-fine-adjustment-in-both-axes.html If you're wanting an equatorial mount, which will enable the telescope to follow an object in the sky, this is an example of one that would support said telescope... http://www.bintel.com.au/Mounts---Tripods/EQ-Mounts/SkyWatcher-EQ3-Deluxe-Mount/1560/productview.aspx
  6. Here are a couple of others to consider. Either one would be very good for viewing the Moon, the planets; and deep-space objects, too... http://www.firstlightoptics.com/beginner-telescopes/skywatcher-explorer-130.html http://www.firstlightoptics.com/beginner-telescopes/skywatcher-explorer-130p.html The second one would be more versatile, more easily managed, and for observing most everything in the night sky. I prefer suggesting Newtonians for children. They're not designed for use during the day, for terrestrial observations, and when the Sun is out. Newtonians are much safer in that regard, and designed to observe the night sky.
  7. I've had these colour filters for a number of years, and I've yet to use a single one. Lumicons, made in Japan, save the ever-popular #80A in the square case which is emblazoned "USA"... The 80A was back-ordered at the time. It arrived a year or two later, and after I had forgotten all about it.
  8. Incidentally, you'll rarely if ever see a mention of the ability to use a Moon filter when observing the Sun, the latter with a SAFE solar filter in place and in addition, and within the advertisements. But users most certainly can, and do.
  9. Not only is the price for just the shroud, it's a second to boot. Don't despair, as a 6" Dobsonian is reasonably-priced, and would "knock your socks off" in comparison to said refractor... http://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-150p-dobsonian.html
  10. The 80mm refractor will make for an excellent complement to the 6" f/8 Dobsonain. Well done.
  11. Hello Spoon, and welcome, If you might be just as interested in seeing Jupiter, and more besides, much more, then a 6" f/8 Dobsonian, as suggested, would be a telescope for you and the child both to enjoy, and for the child to grow into as he ages... http://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-150p-dobsonian.html It's most popular, and a bit tall, granted, but such would inspire a child to reach for the sky, thereby kindling and sustaining a keen interest, perhaps for a lifetime. It would not be a toy, however, and adult supervision would be required until the child is old enough to understand and appreciate its intent as a telescope to be enjoyed for years if not decades to come. This one would be more portable, would also require supervision, and a worthwhile upgrade from the one in question... http://www.firstlightoptics.com/reflectors/skywatcher-heritage-130p-flextube.html The Heritage 130P is quite popular. Its sister, the AWB OneSky, enjoys considerable popularity... http://www.cloudynights.com/topic/463109-onesky-newtonian-astronomers-without-borders/ That thread is a light-year in length. Both telescopes are Newtonians, and with prized parabolic primary mirrors, and for best image. One would need to collimate it on occasion... http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm Collimation is not the beast that it may appear at first, and is mastered soon enough, particularly if one likes to tinker. With Newtonians, one gets the most aperture per pound spent. For maintenance-free performance, and more comfortable use, refractors are preferred, but they are more expensive due to the optical-quality glass used and the amount of work required to figure the lenses. Four individual sides must be figured for a refractive doublet, whilst only one is figured, the primary mirror's parabola, in the case of a Newtonian; the optical flat notwithstanding... http://www.rothervalleyoptics.co.uk/skywatcher-mercury-707-telescope.html http://www.rothervalleyoptics.co.uk/skywatcher-evostar-90-az3-telescope.html I would recommend a Newtonian, however, and for its improved light-gathering capability.
  12. The 6" f/8 Newtonian would be more of a specialty instrument; again, for lunar, planetary and stellar, and some deep-sky, observations. It would be a near-simulation of a 120mm f/10 apochromatic refractor. Less-expensive eyepieces, along with the natural and artificial atmospheric effects, would be more "forgiving" of its nature. If, on one night, the 8" f/5 proved to be uncooperative, the 6" f/8 could be used instead. Granted, the longer optical tube might prove unwieldy at times, especially on an equatorial, but its optical performance would perhaps compensate for the trouble. The 6" f/8 was very popular in the 1950s, '60s and '70s, and when amateurs observed within the solar system rather than deep space. They were quite expensive for the time, and for good reason, per this advertisement from 1960... http://www.company7.com/library/graphics/criterion_rv6-1960_733964.jpg In said age, it was as though it was forbidden to observe beyond the solar system, lest one encountered the "Medusa". It has its adherents, and to this day, but mostly in the form of a "Dobsonian". That said, by all means go with an 8" f/5. I have one myself, but I've yet to observe with it. I've had it since 2003; odd, that, eh? I would recommend flocking the tube throughout, and perhaps even adding an extension to the front of the tube, and to keep stray light out; oh, say, 8" to 10" beyond the edge of the opening. One can be made with most any material. I'd make mine of aluminum sheeting, riveted and lined with flocking.... http://s110.photobucket.com/user/tinker3480/media/Deepspace/DSC_9561.jpg.html Both suggestions would increase contrast, noticeably, and effect blacker sky backgrounds around and about the objects observed. An 8" Schmidt-Cassegrain would be an option as well; more ergonomic and easier to handle. It would favour lunar, planetary and stellar, and just as the 6" f/8; more so in fact, with its 2032mm focal-length. The faster Newtonians would favour deep-sky, and ideal for darker sites. The most important thing of all: don't be in a hurry in deciding. Research, for weeks if not months, and most certainly do not rush out and get one eyepiece after another, especially sets, afterwards. It's best to get one at a time, tailored to the individual and the telescope, and of better quality. The sky isn't going anywhere.
  13. In addition to the use of a Moon filter, whether variable or fixed, an off-axis mask can also be used to dim the Moon. The dust cover of the 200P has an off-axis clear-aperture built in, as seen in this image... http://www.forthimage.co.uk/wp2/wp-content/uploads/P1000679.jpg One of the two smaller "caps" is actually a cap, and removable. However, I suspect that the telescope would only then be a simulation of either a 50mm f/20 or a 60mm f/17 refractor, and perhaps not worth the while, but an option nonetheless. I have a variable polariser... Actually, a variable might just be the best value of all... http://www.rothervalleyoptics.co.uk/antares-variable-polarising-filter-125.html
  14. Many imagers stress the importance of the stability of the mount. The Celestron Advanced VX, or AVX, is considered entry-level for deep-sky astrophotography. An EQ6 would the next step up... https://watchthisspaceman.files.wordpress.com/2014/08/img_1654-medium.jpg An 80mm ED or apochromatic refractor is considered one of the "de facto" telescopes for deep-sky imaging, but an inexpensive 130mm f/5 Newtonian can be used as well, and perhaps even on an AVX or another EQ5-class mount. The use of faster telescopes results in faster exposures, and less time spent; f/5 to f/6 is fast, whilst f/10 to f/12 is slow. There are many variables in choosing the right telescope. If a single error occurs during a time-exposure, and due to an unsteady mount, the image would become blurred, and all would be for naught. Larger telescopes, like a 150mm f/4 Newtonian, would also serve for imaging on an EQ6, and for galaxies at least... https://www.astronomytechnologies.com/images/Product/large/18868_2_.jpg Imaging is almost totally different from visual observations, and can be very expensive.
  15. This combination would make for an ideal kit for lunar, planetary and stellar(double and variable stars) observations beneath an illuminated dome... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150pl-ota.html http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-eq5-pro-synscan-goto.html Later, an 200m f/5 or a 250mm f/4 might be swapped out, on the same mounting, and for improved wide-field, deep-sky performance... http://www.firstlightoptics.com/reflectors/skywatcher-explorer-200p-ds-ota.html http://www.firstlightoptics.com/reflectors/skywatcher-quattro-f4-imaging-newtonian.html ...however, with the 250mm f/4 for darker sites; also, a coma-corrector would definitely be required.
  16. The telescope of choice among advanced imagers, and for deep-sky, is a 70-80mm ED or apochromatic refractor. Newtonians are also used for imaging, from a 130mm f/5 to a 200mm f/4, and larger even, and for planets and galaxies. Regardless of the telescope chosen, a sturdy and robust equatorial mounting is required... http://www.zodiaclight.com/images/RefractorSetup24Aug08Web359.jpg https://scottastrophe.smugmug.com/Astronomy/The-Journey-Continues-2012/i-QjwR3L4/0/M/IMG_0764_PS5%28crop%29-M.jpg For visual, any telescope may be used. Newtonians mounted on a Dobson-style alt-azimuth mounting are regarded as the "best bang for the buck". Some, on the other hand, prefer the "drawing-room" views of a refractor instead, combined with the lowest maintenance of any other design. Then, there are those who prefer Schmidt- and Maksutov-Cassegrains, SCTs and MCTs for short, and for their compact size and consequent portability. With a Newtonian on a Dobson-mount, afocal-astrophotography is possible, and simply by holding a camera up to the eyepiece and snapping a shot. There are also "astro-webcams" one can use. My 6" f/5 Newtonian was once on a Dobson-mount, but then I transferred it, and to a traditional alt-azimuth... I find that I use it more often as a result, and I've taken quite a few afocal photographs with the kit, and again, by simply holding a camera up to the eyepiece... For visual, along with afocal astrophotography, and similar to my own kit... http://www.teleskop-express.de/shop/product_info.php/info/p26_GSO-150mm-F5-Newtonian-Telescope-OTA-2--Crayford-focuser.html http://www.teleskop-express.de/shop/product_info.php/info/p1753_TS-Alt-Azimuth-Mount-Deluxe-with-worm-gears---up-to-8-kg.html For visual, along with advanced astrophotography... http://www.teleskop-express.de/shop/product_info.php/info/p3933_Skywatcher-Explorer-130PDS---130mm-f-5-Newtonian---2--Crayford-focuser.html http://www.teleskop-express.de/shop/product_info.php/info/p3800_Skywatcher-EQ-5-PRO-SynScan-GOTO-Mount-with-tripod.html ...for examples.
  17. You might consider that you should get the 8", then some accessories with the balance. I'm a firm believer in placing all of one's wherewithal, at any given moment, into the telescope first, but only if warranted; then over the months and the following year, and years even, acquire additional eyepieces and accessories as needs or funds permit. A 10" would be a real treat, although it is more difficult for an optical technician to accurately figure a 10" f/5 parabola compared to that of an 8" f/6, therefore the risk of a "dud" may increase with the former; a worst-case scenario, however. In addition, the effects of coma would be greater with the 10" f/5, which may or may not necessitate a coma-corrector, depending on how bothersome it might prove to be. Both would favour deep-sky observations, but also quite capable of the higher magnifications associated with lunar, planetary and stellar observations, and per their relatively-long focal-lengths: 1200mm for the 8", and 1250mm for the 10". Per the 50x formula, an 8" can realise up to 400x, and a 10", 500x, but only under theoretically-ideal seeing conditions, which are rare. In real-world conditions, an 8" might realise 240x, and a 10", 300x; at most, and under average seeing. Higher magnifications also reveal the quality of the mirrors' figures, during observations and when conducting star-tests. Telescopes and binoculars are extensions of our eyes, our pupils specifically, and to see farther and more brightly. Our eyes alone are weak in comparison; among the weakest in the animal kingdom. Ergonomically, an 8" is easier to lug about; but ergonomics aside, just how large of a "pupil" would you like... The increase in light-gathering area is readily apparent, and with the 7mm circle in red illustrating the maximum diameter of the dark-adapted pupil of the human eye. The diameter decreases as one ages, and down to 4 to 5mm in advanced age, depending. Then... If you get the 8", you may forever wonder what the 10" might've been like.
  18. Another telescopic design to consider... Refractors are more expensive, owing to the additional man-hours and optical-quality glass required, for the figuring of at least four surfaces for a doublet lens, and six in the case of a triplet, and as compared to figuring only a single surface for a Newtonian's primary mirror. Also, optical-quality glass is not required for mirrors. http://www.bhphotovideo.com/bnh/controller/home?O=&sku=1141674&gclid=CP3Vv661lcoCFYI_aQodn9EODA&Q=&ap=y&m=Y&is=REG&A=details The 102mm/4" f/6.5 refractor linked to in the above will exhibit chromatic aberration, or false colour, when aimed at brighter objects, especially the Moon, Venus, Jupiter, Saturn perhaps, along with the brighter stars. It excels, however, under dark skies for dimmer, deep-sky objects, and would offer a wide field-of-view just as the 5" Newtonian. Eventually, it would require a mirrored 90° star-diagonal for best performance, and at least a 2x barlow perhaps to observe within the solar system with the higher magnifications. A 2x barlow would also help in that case with the 5" Newtonian, too.
  19. "I hope the above notes prove useful for anyone considering a ~32mm 1.25" eyepiece..." Indeed they did. Thank you!
  20. A zoom ocular is ideal for that very thing; as a teaching tool, and in order to determine which dedicated oculars would be best in future. I'd go with either the Celestron or Sky-Watcher in that event.
  21. Per the stated budget, this would make for a basic introduction; into the workings of an equatorial mount, and with a good-quality Newtonian that is somewhat popular among imagers... http://www.telescope.com/Telescopes/Reflector-Telescopes/Reflector-Telescopes-for-Beginners/Orion-SpaceProbe-130ST-Equatorial-Reflector-Telescope/pc/1/c/11/sc/339/p/9007.uts?refineByCategoryId=339 The mount can also be motorised, for hands-free tracking and short-exposures... http://www.telescope.com/Accessories/Telescope-Drives-Controllers/Orion-EQ-2M-Electronic-Telescope-Drive/c/3/sc/46/p/7827.uts?ensembleId=6 A 130mm/5" telescope would be quite the performer under said dark skies; and at f/5, well-balanced between deep-sky and lunar/planetary/stellar observations. Afocal-astrophotography would also be an ideal introduction into imaging, and simply by holding the DSLR camera up to an eyepiece and snapping a shot. There are also "astro-webcams" that can be used as well... https://www.google.com/?gws_rd=ssl#q=astro+webcam I've taken many afocal photographs myself, and with a 150mm/6" f/5 Newtonian mounted on a simple, non-motorised alt-azimuth... Or... https://www.astronomics.com/6-f8-traditional-dobsonian-reflector_p20339.aspx ...or... https://www.astronomics.com/8-f59-traditional-dobsonian-reflector_p20340.aspx
  22. My 150mm f/5 Newtonian came equipped with a 1.25" plastic focusser; a pity, being of plastic, but usable. I had purchased a Tele Vue 43°40mm Plossl many years ago. I didn't know any better at the time, and I've come to regard it as not much more than a paperweight. To correct that mistake, I've finally settled on one of a somewhat shorter focal-length. It came down to either the GSO or the Baader 32mm Plossl. However, after careful research, it came down to the Baader, and this one... I haven't tried it out yet, but I am hopeful.
  23. A 32mm(31x) with a 200mm f/5 affords an exit-pupil of 6.4mm, and ideal. A 38mm(32x) with a 200mm f/6, as Ed's, results in an exit-pupil of 6.3mm, and also ideal. Splendid!
  24. It's an Astro-Tech Voyager I, and discontinued. However, this is the exact same mount, and in black, but the extension pier and eyepiece tray have not been available for many years... http://www.teleskop-express.de/shop/product_info.php/language/en/info/p1753_TS-Alt-Azimuth-Mount-Deluxe-with-worm-gears---up-to-8-kg.html This is how it actually appears... http://agenaastro.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/p/a/pamt-gs-svaltaz-2s_1.jpg It would be a very good match for the ST80, both aesthetically and functionally. I also use it with two of my other telescopes... Incidentally, it's a Taiwanese clone of the discontinued, Japanese, Takahashi "Teegul"... http://www.scopereviews.com/teegul2.jpg ...and for a third of the price.
  25. I have an 80mm f/6 achromat... An 80mm is pleasantly bright, and manageable. I carry mine outside with one hand. I'd go with it, but get the one with the tabletop mount, and for only £6 more, for it also comes with an astronomical 90° mirrored star-diagonal, and ideal for use at night. The OTA alone comes with an Amici-prism/terrestrial 45° diagonal, for use during the day, but unsuitable for nighttime use.
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