December 3, 2014 – Welcome to My Astro Blog! History of My Astronomizing, Part 1

Having bought a brand new Celestron NexStar 127SLT Maksutov-Cassegrain telescope just about a month ago, I thought it would be a good idea to start keeping a blog about not only my observations but also the upgrades I’ll be making to my scope .  This first post is probably going to be much, much longer than others, because I want to introduce myself and give my background, at least astronomically speaking.

When I first got the new scope on Election Day, of course I had the astronomer’s curse upon receiving new equipment – clouds.   I had just come back from working 16 hours straight at the polls, so I was not in any kind of condition to look at anything anyway.  The clouds cleared after a few days, and I took a look at the waxing gibbous moon on Friday, November 7.  And boy, did I ever look!  I looked at the moon for a good 2 hours that first night.  I was wowed by what I could see with this 5-inch Mak.

A Mak is a very different kind of scope than what I had previously used in the course of my astronomy life.  But to discuss this scope, I have to first go through the other four telescopes I’ve owned so far.  All of the other scopes I’ve previously owned have been Newtonian reflectors.  Two of them were back from when I was a teenager over 30 years ago.  The first was a 6-inch Criterion RV-6 – the classic! – which I had for just under a year.  I returned it to the company due to a bad motor drive, took the refund money and some additional paper route money and moved up to an 8-inch Meade reflector which I owned for about 5 years.  When I went away to college, I sold that scope, essentially for beer money.

I didn’t get back into astronomy at all for another fifteen years, when I took a bonus that a client had given me and bought a terrible 4 1/2-inch Simmons reflector off of Astromart for about $200 or so, way back around 1998.  (Yes, incredibly, Astromart existed even way back then.) This was a real “department store” scope – I hadn’t done my homework, as the internet was a lot less sophisticated back in its early days, and I got snookered.  It was cheaply made, with a terrible equatorial mount, and it came with incredibly cheap eyepieces – I’m talking about Huygens and Ramsden here.  It just never really worked very well.  After a few years of not using it, I gave it to a nephew who didn’t use it at all because it was so difficult to use.

Fast forward another half a dozen or so years, and I decided it was time to get a scope again.  I did a bit more homework this time, and ended up buying a 5-inch reflector from Meade, the model DS-2130AT, for about $400 and change.  This was a computerized “goto” scope, which I hadn’t heard of up until that time, which was about 2006.  With this scope, you had a computerized hand controller with about 10 buttons, and a motor.  You started up the computer, aligned the scope to a couple of stars, and the computer would then be able to show you anything you wanted in the sky.  Well, anything you wanted that the 5-inch aperture was capable of seeing.

Unfortunately, I once again didn’t do my homework as well as I should have.  When I bought the scope, I had a choice between the Meade, and a similar Celestron computerized scope.  What I failed to realize was that this Meade scope was a terrible design, called a Bird-Jones.  Doesn’t sound too promising, does it?  This allows the scope to have a reasonably long focal length in a very short tube scope.  Longer focal length means higher magnification.  They get this longer focal length by essentially taking a Barlow lens and gluing it onto the tube end of the focuser.  Yikes!  The Celestron had a normal, longer tube, but I didn’t notice this crucial difference between the two scopes, and I picked the Meade because it could use larger 2-inch eyepieces instead of the standard 1 1/4 inchers.  Once again, I got snookered; although this time, it was entirely my fault, because the information was out there by this time.

Little did I know – because it had never come up during the entire time I owned telescopes as a teenager – that the mirrors in a reflector had to be adjusted, a process named collimation.  This just wasn’t a subject that ever came up 30-35 years ago.  But it came up now.  After using it maybe a dozen times over the next few years, my Bird-Jones got misaligned.  This is normal as time passes, as a telescope endures a bump here and there.  These bumps eventually knock the mirrors ever so slightly out of alignment, and the view of objects through the scope start deteriorating, getting fuzzier and fuzzier.  My attempts to realign it all ended in abject failure, partially because of my own personal limitations with spatial relations – I couldn’t solve a Rubik’s cube in 5 lifetimes – but mainly because Bird-Jones scopes are basically uncollimatable.

Oh, there are plenty of videos and websites devoted to collimating a regular Newtonian scope.  But none of them deal with the very different Bird-Jones design in any way.  For example, your general Newtonian reflector has a parabolic mirror.  The Bird-Jones has a spherical mirror, which makes things different.  After weeks of trying to glean the internet for information about collimating this thing, I found out the only way to do it was to essentially take the entire telescope apart.  This was because, first, I had to center-spot the mirror.  This meant that I had to physically remove the entire mirror and the thing that holds it, called the mirror cell, entirely out of the telescope, so I could put a spot right smack dab in the center of the mirror to help align it properly during the collimation process.  The second thing I learned was that I had to take apart the entire focuser, remove it right off of the scope, to get access to the lens at the bottom of the focuser.  That lens had to be removed in order to collimate the scope properly.  No way I’m handy enough to do all of this!  Into the closet it goes, to gather dust until I can figure out the “final solution to the Bird-Jones problem.”  MUHAHAHAHA!!!

This meant it was new scope time.  Yay!  Before my adventures in miscollimation, I had done weeks of research as to the right scope for me, and I had decided that I should get the Apertura AD8, a fine 8-inch dobsonian from a company called Opticsmart.  But now that I had been effectively scared off of ever being able to collimate anything, I didn’t really want to get yet another Newtonian.  Yes, the websites and YouTube videos show how “easy” it is to collimate, and they take you through step-by-step.  I could probably do it.  But now I had become very collimation-averse.  You could even say collimation-phobic.

And besides, the AD8 that I was interested in to observe from home, here in the middle of light-pollution central, the Upper East Side of Manhattan, needed to be completely tricked out.  I needed to have setting circles on the scope to have any hope of being able to find anything.  And if I were going to have setting circles, I needed to have leveling feet to make sure the scope was perfectly level so that the setting circles worked properly.  And since I was going to be observing from the roof of my apartment building, where there is a TON of ambient lighting, I needed to have the scope flocked (which means lined with a deep black, non-reflecting material) to stop internal reflections of light within the tube from ending up in my eye.  Flocking increases contrast, which is important in locations with local light pollution.

All in all, the AD8 was going to cost about $730, which is a hefty chunk of dough, especially when you’ve been unemployed for a year, like I’ve been.  Although I must say, from everything I’ve read about them, and I’ve read a lot, the Apertura line of telescopes are well worth it.  But now that I had taken a stand against collimation, the AD8 – and all Newtonians – were out of the running.  I needed a scope that didn’t need to be collimated.  What kind of scope is that?  Well, there are refractors.  But they start getting pretty expensive pretty quickly once you get above the introductory models at 70, 80, and 90mm.  Those are fairly small apertures to do any kind of serious amateur astronomy, especially with the light pollution I have to deal with.  And, of course, because of that heavy LP, I still needed to have some sort of assisted way to point the scope.

And then I came across the Mak design.  And more particularly, I came across the NexStar 127SLT, selling at Amazon for a very reasonable $429, with a 90-day return policy during the holiday season (November 1 – January 31), plus a two-year warranty from Celestron to boot.  This scope was very similar to my existing Bird-Jones scope in some significant ways.  It has the same aperture; it has the same type of motorized computerized goto system; it was also a compact design, great for apartment dwellers like me.

But there are also some very important differences in telescope design between the Mak and the Newt, which I’ll talk about in Part 2.

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6 thoughts on “December 3, 2014 – Welcome to My Astro Blog! History of My Astronomizing, Part 1

  1. Fascinating and enjoyable read, very interesting of your telescope pursuits and experiences in detail. My personal thoughts the simplest way to collimate Jones Bird telescope is to use a distant pointed light source, whether man-made or a real stationary star like Polaris. Adjust the secondary mirror until you get the least blur with a low power eyepiece, or as clear an image as possible, and move up in magnification and adjust again. I have a 150mm Jones Bird telescope and that’s how I collimate mine as best as I could. As the mirror is spherical (and not parabolic), there’s no pressing need to centre dot the main mirror as there is not a ‘sweet’ spot, ie, no point of focus for a spherical mirror. Hope that helps. Thanks again for your blog!

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    1. You’re welcome! Yes, I suppose that is a way to do a rough collimation of a Bird-Jones scope. But with all my fiddling with it, I have thrown it so far out of collimation at this point that nothing except a full-blown collimation, complete with center-spotting of the mirror, and removal of the entire focuser to remove the corrective lens, would be required to get this thing back into alignment so as to be able to see anything. And by the way, in a Bird-Jones collimation, that focuser removal process has to occur twice – once to take the lens off, then you put the focuser back in to actually collimate. Then you have to take the focuser off again to put the lens back in, followed by finally putting the focuser back on.

      Regardless, right now, I have messed with it so much that the focus point is a good two inches outside the focuser. In other words, you have to use the rack and pinion focuser to extend the eyepiece as far back as it will go, then take the eyepiece and slowly lift it up and out of the focuser until there is a two-inch air gap between it and the focuser. I have no idea what I did to get it to this state. But more importantly, I just don’t have the mechanical or spatial ability to try to figure it out.

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  2. Hi Jon,

    Link above is someone going at length how to collimate a Jones Bird telescope, esp from 8.20 onwards.

    But I don’t think this is all that collimation is a must/necessary unless you want 20:20, eg, to split double stars and get perfect diffraction rings on star images at high powers, and if yes, JB scopes are not the ideal pick for it. They are best used for lower power, deep sky objects.

    As for your JB scope re: now focus at 2 inch outside the focuser, if you did manage to take the corrector lens out when you tried to collimate, then the explanation of what you have seems to be the corrector lens went back in the wrong way. To fix it, you flip the corrector lens around and put it back in the base of the focuser tube.

    If you never took the corrector lens out, then it is hard to move the primary and secondary by that much to achieve focus 2 inch clear of the focuser (or unless your BJ scope don’t have the corrector lens anymore?), as primary mirror shouldn’t move that much from the 6 screws (or knobs) to get you 2 inch clear from focuser, the 3 screws that stood higher are to adjust, the 3 lower screws next to each of the higher screws are to lock the primary mirror position in place.

    The secondary mirror, the central screw adjusts the distance of secondary from primary, the 3 surrounding the secondary mirror holder is to adjust the tilt to ensure everything looks concentric from the reflected image via the secondary mirror. Likewise, hard to get that out of collimate to get 2 inch clear of focuser to achieve focus.

    I read a lot from the internet after I got my JB telescope 2 months back (thus I found your site). I now understand the current commercially produced JB design has been deviated a lot from the original JB from Jones and Bird, the original inventors. That is, it was never meant to be a corrector lens located at the base of the focuser but should be between the primary and secondary mirror instead, and the corrector lens is meant to be a larger diameter corrector lens to correct the spherical aberrations, not the small corrector lens that fits inside its own retainer ring (further stopping down the usable diameter of this lens), inside the base of focuser tube.

    As such, the current commercially produced BJ scopes with corrector lens at the base of the focusers tend to produce sub-par optical performance, ie, less than crisp and clear image once above 100x and at low magnifications, only the central 40% of the eyepiece is clear, the peripheral being blur from spherical aberration.

    Hope that helps. I like your blog, learning heaps from reading your detailed description and experiences with your telescopes, eyepieces and mounts.

    Thanks.

    Kind regards,

    Bill

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    1. Bill, as you point out, the Bird-Jones design is implemented very poorly when it is used, so that the maximum magnification is only 100x. A 5.1″ scope should easily be able to attain 200x and more. As I have both moved on from the scope, and because of my pseudo-dyslexia when it comes to fiddling with these sorts of things, I just don’t have any interest in trying to fix it. Thanks, anyway.

      Meanwhile, I am actually using the scope, but not as you might think. My NexStar mount is currently in the shop at Celestron (and has been for almost two months now) for the exact same reasons I discuss in my December 5 blog entry – the clutch was slipping, and it wasn’t tracking very accurately. Celestron – whose warranty states that they will fix problems within 30 days – has promised to return the mount by next week, but we’ll see about that. For the past two months, the only use I get out of this Bird-Jones scope is as a mount to strap my ST-80 to so I can still go out and observe.

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  3. Hi Jon,

    Many thanks for your quick reply.

    Great to hear the JB scope mount is being used. Agree, 5 inch scope should be capable of around 200x, if not 250x for crisp and clear views. But commercially produced JBs with corrector lens at the focusers (being catadioptric Newtonians) are just a bit soft at high magnifications compared with other telescope designs or their Newtonian counterparts.

    Nevertheless, a 5 inch JB scope is still a great window to the universe, compared with my naked eyes, 7 x 50 binoculars and 60mm refractors (which I had when I was a kid), provided I accept a JB as it is.

    PS:
    Hope Celestron will do the right thing by you with their 30 day turnaround on your Nexstar mount and do what they guaranteed, as they are such a big marketed telescope brand. If not, may be air it on your blog or tweet it, they may then contact you and look after you properly.

    I bought my JB scope second hand, so accepts it as is, blemishes, chips, faults and all with no returns. The scope is fine, other than it is JB, the German equatorial mount it is mounted on can be a bit weak, as the right ascension gear is a bit worn (getting threaded at certain places), Despite my fix, the slow motion control for the RA gear can be temperamental depending on the angle the scope is pointing and which gear threads I have reached and whether they are threaded already.

    Thanks again.

    Bill

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