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Posts posted by Alan64

  1. Quite a few double-stars require higher powers to split them, and to see the differing colors.  A short-focus achromat(refractor) and a short-focus Newtonian/"Dobsonian" are going to be problematic in that regard.

    Still, refractors and Maksutovs are best for double-star observations.

    In so far as light-pollution, there are several ways to lessen its effects whilst observing, and with some requiring a bit of DIY, arts-and-crafts type work.

  2. Your kit is very similar to this one...


    I have a finderscope that's just like it, and from an entry-level kit I got back in February...


    To improve the stability when adjusting it, and to preserve the alignment for a much longer period of time, line the front portion of the tube-holder with the thinnest self-adhesive felt you can find...


    Or, you can use masking-tape, or whatever else that would work.  You simply want to thicken the circumference of the holder, and inward about a half-inch or so from the front.  You can apply whichever to the tube itself, but it works best inside the holder instead.

  3. On 29/06/2019 at 00:28, Astrotamer said:

    Hello ,I am a begginner at astonomy and  I have bought slt 130 telescope.What i need to buy to have the perfect observation in solar system and deep sky objects?



    Your telescope has a focal-length of 650mm.  That's a bit on the short side in order to realise the higher powers associated with lunar, planetary and double-star observations.  That's where you have two choices: either a 2x and a 3x barlow even, with Plossls, or more expensive eyepieces that have barlowing lens-elements already built in.  A 130mm aperture is theoretically capable of up to 250x, but there are a few variables that will prevent that, one being the atmospheric seeing conditions.  Near the horizon, observing through the atmosphere is akin to looking through a bowl of broth.  The atmosphere is thinnest at the zenith, straight up overhead.  Planets become interesting at 150x or so...

    650mm ÷ 150x = a 4.3mm eyepiece, or 4mm to round it off.  Some combine a 12mm Plossl, or other design, inexpensively, with a 3x barlow for a simulated 4mm.  Others choose eyepieces that have barlowing lens-elements, with wider fields-of-view, longer eye-relief, and larger eye-lenses through which to see; for examples...

    https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-5mm-ed-eyepiece.html (130x)

    https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-32mm-ed-eyepiece.html (203x)

    With a go-to mount, like the SLT, it's easier to reach those higher powers.  The collimation of the 130mm f/5 Newtonian should also be spot-on, as a telescope has to work harder to produce sharp, pleasing images at those higher powers.  Also, with a go-to mount, you don't really need wider-angle eyepieces, as the mount keeps you from having to bump and nudge the telescope in order to keep an object in view.  On the other hand, if you prefer a bit of perspective, a bit of "real estate", the black sky surrounding the object, then wider-angle eyepieces will provide that.

    The telescope itself comes with a 2" focusser.  You might choose a 2" 32mm 70° eyepiece, and for your largest view of the sky, for deep-sky venues and vistas; for example...

    https://www.firstlightoptics.com/ovl-eyepieces/panaview-2-eyepieces.html (20x, and binocular-like)

    That's the lowest-priced option for a 2" low-power eyepiece, therefore you might see some distortions at the edges of the view, but it wouldn't render it useless.  Else, you can choose a 32mm Plossl; for example...

    https://www.365astronomy.com/32mm-GSO-Plossl-Eyepiece.html (20x)

    For medium-power observations, choose an eyepiece from 12mm to 16mm, or even a 20mm, a Plossl or a wide-angle.  Do not choose Plossls shorter than 9mm, unless you want to rough it.

  4. 1 hour ago, devdusty said:

    Thanks to everyone for their advice and comments. I note your recommendation Alan for the Skywatcher Evostar 90mms reftactor.

    In fact my daughter bought this for me 5 years ago as a combined 65 th birthday and Xmas present. I selected it as I was advised it was suitable for towns with bad light pollution.

    I found it too long and bulky for me to carry in  and out to the back garden.

    Also I never got to grips with the equatorial mount.! It never seemed to move in the direction I wanted it to.

    The other telescope that might just be in my price range is the Skywatcher Startravel 80mms refractory on an altazi muth mount.

    If anyone has advice or comments about it , I would be grateful to hear them.

    Chris P

    Similarly to John's suggestion, I had initally thought of a 90mm Maksutov as an option, and when I was composing my previous reply, but I didn't mention it because it and a mount may go over your budget.  Nonetheless, that would be an ideal telescope given the observing agenda and the desire for an ease of handling.  This Celestron C90 Maksutov, which belongs to a relation, is shown here mounted upon my revamped EQ-1 equatorial, which is the very smallest of equatorial mounts on the planet...


    The two go together like Punch and Judy, but I wanted you to see just how diminutive a 90mm Maksutov is in fact, given your handling concerns, and if you might within the mind, to compare it to your Sky-Watcher 90mm f/10 achromat.  This is my Meade 90mm f/10 achromat, and on its EQ-2, which is the next size up from an EQ-1...


    Incidentally, your 90mm f/10 achromat is also mounted onto a larger  EQ-2.

    Here they are, two 90mm telescopes, yet of differing types, side by side...


    Now picture that 90mm Maksutov upon an alt-azimuth, and it wouldn't have to be a large one, comparable even to the size of that diminutive EQ-1.  Don't consider an AZ-3, no, but this one rather...



    By the way, why is that dovetail-bar upside-down???

    Then, there is this whole kit, with that same alt-azimuth mount, but with a 100mm Maksutov...


    Either would make for an ideal kit for your purposes.  I do realise that it's more costly.  Else, I'd go with the Sky-Watcher 130P, and place it on a table in the garden.  If not that one still, then perhaps this kit...


    • Like 1

  5. On 13/06/2019 at 10:28, devdusty said:

    Further to my post about the Skywatcher flexible 130 p, I am now looking at a short focus tefractor. I am 70 years old so can only manage to carry a fairly lightweight telescope into my back garden.

    I am interested in viewing the moon, double stars,  bright planets and the brighter star clusters.

    I am looking to purchase one of the following

    Celestron  travel scope 70

    Bresse r Classic 70/350

    Skywatcher mercury 705 70mms.

    I understand that these telescopes have limitations, but they the only ones in my price range.

    Any comments or advice would be welcome.

    Chris P

    You have quite the conundrum there.  On the one hand, you want a kit that's light in weight, but on the other you want a telescope for lunar, planetary and stellar observations; the brighter objects in the night sky.  That's where an entry-level refractor might fail you, as short, achromatic refractors exhibit false-colour when aimed at the brighter objects, and resulting in images that are less sharp and clear.  In addition, the shorter focal-lengths of those achromats would make it more difficult to reach the higher powers associated with said observations.

    This kit would be better suited for that...


    It's not big at all, nor heavy.  The equatorial version, if you'd like to track the objects...


    These two 90mm f/10 kits would be the next step up in a refractor...



    ...that is, if you don't want to have to maintain a Newtonian, like the Sky-Watcher 130P "Heritage"...


    That telescope would require a bit more of a learning-curve, but it is compact and with 130mm of aperture.  You would need barlows, a 2x, and/or even a 3x,  to reach the higher powers more readily.

  6. A Maksutov would indeed complement the 130P-DS, as one is the "antithesis" of the other.  The full range of magnifications would then be covered with the two: the 130P-DS for low to low-medium power observing, the Maksutov for medium-to-high powers, and both on the one mount, interchangeably.

    I have my 127mm Maksutov on a manual alt-azimuth, and I have no trouble observing with it...


    ...motioning it to this object and that.  It needs a good finder.  If a lens-type, an 8x50 at minimum, and perhaps with a right-angled eyepiece; or, a reliable red-dot finder.

    The secondary-mirror of a Gregorian or "spot" Maksutov, like the Sky-Watcher and others, including my own there, is fixed, non-adjustable.  It's only the primary-mirror that's adjustable, and rarely does it require same.

    Regardless of the type of telescope, when travelling the telescope should be protected, cushioned with padding or other.

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  7. A 127mm Maksutov, with its much longer focal-length, is more of a specialty telescope, rather than an all-rounder like the one you have now.  Using the same eyepiece, you don't get the same view of the sky with one as you do with the other.  For example, here's the view of the Moon and the sky background with a 32mm Plossl inserted into your 130mm f/5 Newtonian(orange), and versus the same eyepiece inserted into a 127mm(actually 120mm) f/12 Maksutov(red)...


    A Maksutov, since it cannot "see" a large area of the sky, usually requires a go-to mount to direct it.  It can be used on a manual mount, but it would be more difficult to hunt, to locate obejcts.  On the plus side, a Maksutov would make it easier to reach the higher powers associated with the Moon, the planets, and the double-stars; but many deep-sky objects as well.  The views would probably be sharper in addition.

  8. Fair is fair, and for a saving grace, I reinstalled all of the original washers, but used Super Lube as the grease instead of the factory's...

    Much better...


    ...the altitude motion much better indeed.  I would think so, and after all of that.

    Glamour shot...


    No, that's not the Maksutov, as I don't think that the mount can support it properly.  I got the Maksutov for itself, and the mount for my smaller telescopes, like that one, and both within a kit.  That's my Antares 805, an 80mm f/6 achromat.  Incidentally, this was the first time that refractor had been operated above 100x.  Jupiter, at 160x, presented to my eye only a vague incidence of false-colour; a subtle violet veil it was, and barely extending outward.  But so much for that, for it is an f/6 achromat, yet one that may be used to observe the larger planets after all, and the Moon in addition I already know, for myself in any event.

    I then went inside and got the eyepiece-tray and extended the legs of the mount.  Picking the kit up at that point, I could then carry it with one hand with little effort, and over to the south...first-light3.jpg.cb4d60fe1083a35caeff8597aa22aff7.jpg

    The telescope is aimed at Jupiter still, there, and at 80x.  I rapped the tip of my middle finger forcefully onto the center of the telescope's tube: a 3- to 4-second damping-time.  When the legs were retracted earlier, I had done the same, and the damping-time was at about 3 seconds.

    The verdict?  I like this wee mount, a lot, now, and with the alt righted...


    But I still don't like that a metal head is joined to a metal hub via plastic.  There's got to be an alternative, somehow, somewhere.

  9. But before I reveal the final result, the azimuth axis...


    That was easy enough.  But this, not so much...


    I cannot reach the lock-nut for the azimuth's bolt, due to that glued-in plastic disc with the two holes and the threaded brass insert, and without comprising it.  Thoughts...


    Okay, I'm done thinking.  I will leave it alone for now, as it, unlike the alt had upon arrival, operates quite smoothly actually.  But it will be revisited in future, as I do have bronze, PTFE, and Formica #909-42 laminate perhaps, waiting in the wings.

  10. I soak the areas first with 100% acetone.  I then scrape as much of the now-softened paint off and out with a blade.  Next, sandpaper of varying grits, along with a little acetone, and to remove even more paint.  Lastly, varying steel-wools down to #0000, and lemon oil, to tidy up and polish.  The mating surface...


    There, the paint has been removed, but what's that greyish coating; primer for the paint?  Did they actually go to that much trouble there at the factory?  I then sanded it some more with finer grits; this kind...


    ...and polished with the aforementioned...


    No, I did not cause those scratches seen there.  That was the factory's doing, with an industrial wire-brush possibly, and to make the primer and paint stick better, perhaps.  The scratches are, at most, only cosmetic.

    On the flip side...


    Where washers for the bolt come in contact with that surface, and forward of the lock-nut, that was prepared as well.  Beforehand, all surfaces were gritty, rough, like sandpaper itself, and which had scratched and "boogered" up the surface of that large nylon washer.  I then smoothed and polished the washer out with the fine wool and oil, and in preparation...

  11. The mount, an ES "Twilight Nano"...


    ...no slow-motion controls, nor clamps or locks for the axes.

    The knob there, to clamp the head to the hub, was loose within the box; not a big deal.

    Who paints bearing surfaces, I ask.  I know that Synta and Ningbo Sunny do; so why break up a set, as JOC is also complicit...


    At first, I thought that this large washer might be of PTFE(Teflon), but no, it's of nylon, and adequate for this design I suppose...


  12. Second-light...

    I observed Polaris straight-through, without the diagonal, and threw the star out of focus; no change, the patterns were identical to the image shown previously.  I now know that my roulette-wheel star-prism is indeed collimated, as I had renovated and tested it a while back.  I tried to take snaps of the pattern, and with seven shots this time round, but all seven were duds.  Of course, it was more difficult to attempt without the diagonal in place.  I brightened each one even, and nothing appeared.

    In focus, at 190x with the 10mm, on both mornings, I could see the Airy disc of Polaris sharply, and at least two diffraction-rings encircling it, but the seeing, at Pickering 6, from fair to good, mucked the view up a bit, with annoying rays dancing within and about the rings.  On this second night there were a number of cloudlets rolling across the sky, but the haze was gone.

    Jupiter was brighter this time round as a result, like a 40-watt bulb, at 190x.  There would be no seeing any spots this night however, I knew, but it was a good show nonetheless.

    I didn't wait on the Moon, as it was due to appear even later than the morning before.


  13. First-light continued with Polaris, the North Star, at 190x...


    ...most impressive.  Incidentally, I've had my camera, again, since 2002, but it's only now that I've discovered how to adjust the shutter; pathetic, I know.  But as a result, I may now take sharper afocal shots through an eyepiece, and in a split-second.  Right afterwards, I threw Polaris out-of-focus and took ten shots.  All but one were duds.  The one...


    It's there.  Look sharp. 

    Here, I've brightened the image...


    The extra-focal and intra-focal sightings were identical.  

    Now, that's with my Celestron star-prism diagonal integrated, and as it was throughout the first-light. 

    I had thought about this at the time, although not pertaining to this exercise: "Can a mis-collimated diagonal cause a mis-collimated telescope to appear collimated?"  

    Lastly, the Moon...


    The Moon appeared there in the sky as though it had fallen into a bowl of chicken broth, floating just beneath the surface, glowing.  It wasn't very high up above the horizon...



    The live view, of course, was sharper, as always.  I do want this telescope to exhibit what it's capable of, but that's not going to be forthcoming for a while I'm afraid.  There's been too much water around here.  The Mississippi River, the largest in the U.S., is about ten miles to the west of my digs.  Currently, it is at a level and longevity approaching that of its infamous Great Flood of 1927.

    By the way, the mount's been sorted, mostly, and to where it's usable.  I'll be showcasing that in a bit.

  14. "Like the way the inside of the OTA has micro baffles all the way front to back. So much better that just a painted surface."

    Yes, I had seen those online, but not as clearly as this...


    And here I have this new box of Protostar...


    Alternately, I have to wonder if JOC's factory-black is as black as my rattle-can of chalkboard-black.  That stuff is almost as black as a black hole...


    There's got to be something or other within to flock.  I might at least flock from the meniscus almost all the way back to the primary.  The baffled surface would have to be high-glossed, for improved adhesion.  However, I do suspect that in that the telescope will sport a flocked dew-shield 24/7/365, then perhaps said enhancements would be to no avail.

    Incidentally, whilst mucking about inside with the camera, it seems that JOC's clean-rooms, if equipped, aren't up to the task.

  15. 39 minutes ago, johninderby said:

    On the “baffling” subject have you read this? Some very usefull info.



    One of the Orion type finder mount fits directly Using the original holes. Be aware that the rear dust cover of the scope that covers the metal back plate is plastic and the finder screws strip easily. I taped the holes to M5 and it seems solid. You could always remove or just parially remove the dust cover enough to put nyloc niuts on the inside for a really solid job.



    Thank you for that most useful link, John.  

    Yes, I see...


    And here I thought it was of metal.  Why am I not surprised.  Incidentally, the focussing knob was loose upon arrival.  It takes a 1.3mm hex-key, but I'm fresh out of those, so I used one of those tiny flat bits from a mini magnetic screwdriver.

    Also, might I integrate a 2" visual-back to this, please?  Would it be worth it, given the diameter of the primary's bore?  


  16. First light...no, not when I took that image of the leaves during the day...


    The very first celestial object I saw through my new and only Cassegrain was old Jove, and at 190x...


    Of course it's blurred.  I used a 2002 Minolta 4MP point-and-shoot, and with a manual mount.  Still, you can see a single moon at upper-left.

    All four were seen quite well during the live view, naturally.  When I first had the planet in view, I saw one moon emerging from the side of the planet.  It appeared as a little bright dot, and sharp.  That was nice.  

    The image brightened, and now two moons are visible...


    The moon closest to the planet there was the one that had emerged earlier.

    The whole night I was bothered by cloudlets and haze wafting across the sky.  It's nigh summer.  But the haze did have a beneficial effect.  Jupiter was dimmed slightly in consequence, its lovely colouring revealed, as shown. 

    The only detail seen on the planet's surface were the usual equatorial bands; and perhaps, just perhaps, a spot that I think I saw, but cannot say for certain.  This is the eyepiece I used: a 10mm 70°...


    ...and with these strange, amber-like coatings...


    ...much mysterious, that one.

  17. Despite the 1900mm focal-length of this telescope, I have little to no trouble in quickly bringing the objects that I view regularly to bear within an eyepiece: Polaris, the major planets, and the Moon; even in the absence of a finder.  I simply sight alongside the tube.  Here, under Bortle-4 skies, which might easily become -5 in future, there are a number of globular-clusters that I can readily locate, but not by sighting down the tube.

    This is the base for the red-dot finder, and similar to that of a Meade...


    At first I thought it was of metal.  

    I have a couple of Vixen-type bases, but I'll need longer screws to attach one; and yet another trip to my local hardware, to where I've suggested a cot in the back of the store.

    I have this 8x50 straight-through...


    That will do for the time being, and another red-dot that I have in addition.  I'll try both and see which performs best for my purposes.

    The dovetail-bar is of white-painted metal, and with a steel strip fastened onto one side, as a clamping surface.  That of the Bresser is identical, but painted black...


    I'd like to replace it; perhaps tube-rings in addition.  That would add extra weight however.

    The plastic dust-cap has two locking tabs...


    The meniscus is multi-coated and uniform...


    ...and very much like that of my Meade 90mm achromat...


    The secondary-baffle, and flared, like a vortex,...


    That will be altered, or ripped out altogether, albeit ever so gently.  As I understand, the telescope as it sits is optimised for daytime/terrestrial use.  That won't do.  Its presence also increases the size of the obstruction, and that won't do either.

    The primary-baffle...


    The reverse of the Gregorian "spot", and facing outwards...


    I've thought about a matte-black disc.  Schmidts don't seem to have that problem....


  18. OTA5.jpg.1a10b77ff41aa727e99e529489e707bc.jpg

    The collimation appears bang-on fresh out of the box...


    I made a dew-shield straight away, in a pinch, and with these sheets of art-paper...


    As I had said before, the bundled mount, an ES "Twilight Nano", cannot be utilised at present, notwithstanding the fact that it's not ideally supportive.  My only recourse was to place the telescope upon my Astro-Tech Voyager I, a GSO product...


    I didn't dare take it out of the house without a dew-shield, with the micro flora and fauna whizzing round.


    The only thing I could point it at were tree leaves in the distance, lots of them.  So I did, and at 190x...


    The live view was sharper of course, as the eye and mind can follow an object more easily when a breeze ensues.

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