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Alan64

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About Alan64

  • Rank
    Proto Star

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  • Gender
    Male
  • Interests
    ...astronomy, naturally.
  • Location
    Mid-South, U.S.
  1. Alan64

    Flocking a Synta 70mm f/13 Achromat

    Thank you, but I had already collimated it prior to reading your post. Yes, I knew that the laser-diode was encased somehow within, so I did not batten down any screws too tightly. As for the target, about 5.5 metres distant, I taped a sheet of black art-paper onto a kitchen cabinet, and had the collimator on a desk in the living-room. I perched(not attached) a pair of 7x50s onto a photo-tripod in front of the chair I was sitting in, and observed the spot whilst rotating the collimator. When the spot didn't move any longer, I took it off the stand and placed it into the focusser of the achromat to collimate that. That's done as well. In the end, I used the black-oiled socket-head screws, which threaded in a bit tighter than the stainless-steel hex-heads, therefore there was really no need for any other parts to lock the screws in position, not for my purposes indoors... It will never be taken outdoors for use, nor for travelling. I then placed the objective-cell onto the front of the achromat's tube, and collimated that to the focusser, but with a diagonal in place, and with my refractor-Cheshire. Mind you, it's but a 70mm objective, yet I saw the sharply-defined Airy disc of Polaris and its blade-like first-diffraction ring...and at 225x(4mm). I also used Polaris for the star-test, at 150x(6mm), and the intrafocal pattern was practically "textbook", so it appeared. Extrafocally, however, it was a bit of a blur, and due to the seeing I suspect. I'll be star-testing it further in future. I do have some final tweaks to perform before the achromat is at last completed; the doublet's spacers mainly. Also, the Celestron star-prism diagonal, the prism itself, needs blackening.
  2. Alan64

    Flocking a Synta 70mm f/13 Achromat

    The holes of the casing are not necessarily aligned with the threaded holes below. The external thumbscrews had no trouble fitting into two of them, but one of the holes would not play nice... I've since enlarged the area there with a diamond-bit, and an external screw will now thread into it. I had to stuff a bit of cotton into the threaded hole to keep the metal "dust" from falling inside the device whilst grinding. I had not planned for this, but it did work out nicely nonetheless, and in that the widest point of the heads of the stainless-steel screws will clear the upright whilst rotating the collimator... The collimator is now ready to collimate.
  3. Alan64

    Collimation

    Yes, you may want to wait until you're more familiar with the telescope's construction...
  4. Alan64

    Collimation

    The ones within my image are 40mm in length. Simply take a short metric-rule and hold it up against the side of the hub, placing the end of the rule where the screw-tips would touch the back of the secondary-stalk, and determine the length above the hub desired, and enough to ensure that you can get the fingers on them... Theoretically, they could stretch out into infinity and still not interfere with the light-path. My 150mm f/5 Newtonian, along with your Sky-Watcher, were both made by Synta in mainland China. Mine is branded "Orion", of California, and its primary-cell is fully equipped with metal-springs and thumbscrews... That of the Sky-Watcher utilises fastening-type screws and rubber o-rings, there on the right, and with that of a GSO there on the left... Of all the designs of telescopes, the Newtonian lends itself to all manner of enhancements and improvements, and just as I have done for my own. You can replace those screws with M5 thumbscrews, and replace the o-rings with metal-springs. You'll need to study your cell to discover what is possible and what is not in improving its machinations. These links should be of help... https://www.cloudynights.com/topic/515629-skywatcher-6-inch-dob-primary-collimation/?p=6839671 http://www.astronomyforum.net/astronomy-beginners-forum/160480-o-rings-behind-primary-mirror-s-w-8-a.html In addition, research the improvements further, online. The addition of metal springs may require some doing. The design of the primary-cell of the Sky-Watcher came out first, many years ago, and it simply isn't up to the standard of other brandings. That's the problem in a nutshell.
  5. Alan64

    Collimation

    No need for Bob's Knobs; those are for the decorative cowls of Schmidts. Simply take one of the set-screws from the secondary-hub to your local hardware, have it sized, a metric #4 it is more than likely, and get black-oiled socket-head screws instead, like these on my Newtonian... Get them as long as you'd like, so you can get a hold on them with your fingers whilst adjusting. They'll be a lot cheaper than Bob's Knobs. If you'd like you can place a nylon-washer between the back of the secondary-stalk and the screw-tips, and let the screw-tips dig into the nylon instead of the soft metal of the stalk. I glued my washer onto the stalk, but it doesn't have to be...
  6. The Chinese manufacturers are simply cloning what the Japanese manufacturers had produced for decades before the former took it over. In this instance, I'm referring only to EQ-1 and EQ-2 mounts; the running of the mill. It's easier and less inexpensive to produce those, given the first instance. They are most used to doing so. What would be the alt-az equivalents to an EQ-1 and an EQ-2? The Vixen Portas, I'd answer... https://cdn3.volusion.com/psygr.belxm/v/vspfiles/photos/5863TALLPLUS-3.jpg?1455637310 ...although by themselves, each, they're priced at the level of EQ-1 and EQ-2 kits(with telescopes included). Remove the labels, the marques, and see them for what they really are: simple alt-azimuths; the running of the mill yet again. They're no harder to produce, quite easier perhaps, yet they're not included in said equatorials' steads, and for the beginners. Why not? One purpose in including these basic equatorials within the entry-level kits could be, perhaps, possibly, that they just might ensure future acquisitions of EQ-3s, EQ-5s, EQ-6s, and even EQ-8s? But at the same time, they can and have been responsible for confounding many beginners, offing their interest in the pastime altogether, and that is most regrettable. In that regard, the industry is backwards. Incidentally, for decades, in the U.S., Parks Optical produced some of the world's finest Newtonians, and mounted, marketed and sold them on huge, precision equatorials... http://www.parksoptical.com/index2.php?cPath=21_114&cat=Superior+System http://www.parksoptical.com/index2.php?cPath=21_115&cat=Observatory+Series Then John Dobson arrived on the scene, with his miniaturisation of William Parson's alt-azimuth... https://media.gettyimages.com/photos/the-giant-reflecting-telescope-of-william-parsons-3rd-earl-of-rosse-picture-id613477478?k=6&m=613477478&s=612x612&w=0&h=5He1QnP38ZJG_6joWrDeHdY6GVakTB0EQJfK2GTMU8A= ...and eventually put Parks out of business.
  7. Yes, that's the one. Well, some observatories were built at a time when there was little to no light-pollution....but nowadays... How old is this one? You could pull along most any telescope in a cart of some sort whilst walking. If you fitted an easily-detachable sidecar to the bike, you could carry a telescope in that.
  8. I have the same kit, made in the same factory overseas, but under a different branding or marque. It's a 100mm f/4 Newtonian... I consider it a specialty telescope; not really for a beginner. I got it for low, low power observing primarily. One night, I popped in this lovely 30mm, that FLO carries incidentally... ...and then took this afocal shot of the Moon at a low, low 13x... I'm in the process of improving it throughout, after which it will suit the purpose for which it was purchased, and admirably. Perhaps even better, I got mine when it had gone on sale.
  9. A 200mm Schmidt on the SE mount is doable, however in the end it is under-mounted; less cost, less performance.
  10. But for the here and now, I must also say that the best buy, price-wise, would be that 150mm f/8 "Dobsonian"(actually, a Newtonian on a Dobson alt-azimuth).
  11. No, the 102mm f/5.9 achromatic-refractor weighs only 3.6 kg. In any event, this refractor, within this kit, would be better-balanced in observing the gamut; the Moon and planets, and the brighter deep-sky objects, including double-stars... https://www.teleskop-express.de/shop/product_info.php/info/p7793_Bresser-4790907---Refractor-Messier-AR-90-900-with-EXOS-1.html The longer an achromat, the less false-colour will be seen when viewing brighter objects. Chromatic aberration degrades an image; blurs, smears it. Refractors require little to no maintenance, and if cared for they will, theoretically, last forever. I must say, it's a "strange" thing among these entry-level kits that a more-complicated equatorial mount is included, and instead of a more-intuitive and user-friendly alt-azimuth. Alt-azimuths are no more difficult to manufacture, yet the manufacturers seem to think that an equatorial is best for beginners, when it's actually the other way around. Consequently, I think that the industry does this simply to increase profits, and with little to no regard for the consumer. For example, you want a particular telescope, but you have to get an equatorial that's included with it, whether you want it or not. Then the user later acquires an alt-azimuth, and the equatorial gathers dust. The industry knows that an alt-azimuth is more appropriate and popular, and they're going to capitalise on that. Some entry-level kits do come with alt-azimuth mounts, but not that many, and most if not all of those are not of very good quality and stability. This kit would instill a pride-of-ownership, in addition to its performance, like no other kit at its price-point... https://www.teleskop-express.de/shop/product_info.php/info/p2683_Skywatcher-Evostar-102-on-EQ3---Refractor-telescope-102-1000mm.html ...and yes, it too comes with an equatorial.
  12. https://www.teleskop-express.de/shop/product_info.php/info/p2705_Skywatcher-Heritage-130P-FlexTube-Dobson---6years--.html https://www.teleskop-express.de/shop/product_info.php/info/p7222_GSO-Dobsonian-Telescope-150C---6-inch-aperture-with-fine-Crayford-focuser.html https://www.teleskop-express.de/shop/product_info.php/info/p7789_Bresser-4802600---102-mm-Refractor--f-600-mm--OTA.html ...and... https://www.teleskop-express.de/shop/product_info.php/info/p1753_TS-Optics-Altazimuth-Mount-GSAZ-with-fine-adjustment-and-tripod.html ...or... https://www.teleskop-express.de/shop/product_info.php/info/p8069_TS-Optics-Altazimuth-Mount-with-Fine-Adjustment-and-Quick-Release.html
  13. Alan64

    Flocking a Synta 70mm f/13 Achromat

    The stand was complete to use initially, but needed improvement after that. I eventually added a fixed stop at the front, and a spring-loaded one at the rear. To keep the woods used from warping over time, three coats of shellac were applied... The active-stop applies just the right amount of pressure, and to keep the collimator from falling out at the front whilst rotating it. The stand works beautifully now, and the collimator touches no wood, only PTFE. Before the enhancements, I had attempted to collimate the device using its set-screws. At one point, I got it almost bang-on, but then in tweaking it further I only made it worse. I then decided to remove the set-screws, and to explore the nature of the system. The short one was under the label... ...hardly intuitive. Why that one is shorter than the other two is beyond me, as it screws down to the same depth. Perhaps they ran out of the longer ones at the time of its assembly. In this case, I will not be using this collimator outdoors, nor for travelling; rather, in a laboratory-type setting, although a laboratory I do not have... ...just some things to get my fingers on.
  14. I suppose that there is that caveat. I've noticed that the Celestron, which appears identical, is almost twice the cost there in the UK. That's the one I got here in the U.S. I haven't used it yet, but I do seem to remember reading about its performance in cold weather during my online travels. I wouldn't be using mine in the cold anyway, as I get chilled quite easily. I generally turn to philately during the winter, which is my secondary hobby.
  15. The soda-can is only to illustrate the size of the kit. I would prefer observing with an equatorial, but they're such beastly things, and I would have to mount that 70mm on at least an EQ-2 if not an EQ-3. I have an EQ3-class mount, a Celestron CG-4, but not an EQ-2 unfortunately, and I've yet to use the CG-4. I've fixed it up exactly how I want it, and it's still a beast... I want to add that wee 9V-battery Celestron motor-drive to it that I got recently for the EQ-1 of that 70mm kit, and for both mounts. I don't look forward to using the motor-drive kit that I got for the CG-4 back in the day, as I can't adjust the speed, and it would need to be connected to the mains. Incidentally, that's a thought: you can get that 9V motor-drive for yours, and enjoy automatic hands-free tracking of any object, It has a varistor for adjusting the speed, to where you can have an object perfectly-centred and standing still there in the eyepiece, and for hours... https://www.firstlightoptics.com/all-mounts-motors/ra-economy-motor-drive-for-eq1.html The listing states "single-speed", but it's actually variable. I use that alt-azimuth, illustrated previously, exclusively, and for all of my telescopes. Did you know that you can convert your EQ-1 into an alt-azimuth, and back again, very easily?
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