Alan64
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Posts posted by Alan64
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The aluminum-splint and the plastic-stalk must be made as one. For the next step, I made a small rule, or straight-edge rather...
I then marked each side of the plastic stalk, ground them out flush with the aluminum-splint, and scored the depressions...
Bronze plates; and custom clamping-pads of maple, hard-felt and wax-paper, which ensure that the plates lay perfectly flat......
The plates were epoxied into place, and clamped until the epoxy cured. Here, the removal of the clamping-pads...
...then the wax-paper...
The stalk and splint are now as one.
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Can't neglect the plastic-stalk, as it needs bolstering as well where it joins the frame...
Where the stalk joins the hub, I installed a U-shaped bronze rod...
You can see it there peeking out at you, and that to strengthen that union further.
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A hole was drilled at each end of the splint. for epoxy to flow into, and for securing further; every little bit helps...
There at the left, that's the "claw" of the splint.
Test fitting...
The splint and its support were then epoxied into place with J-B Weld...
All surfaces to be joined, as usual, were scored. Note how the "claw" of the splint disappeared into the hub...
The hub's well there for the favoured stalk was primed with a coating of plain epoxy, then epoxy infused with dust of rosewood was packed in all round and about the "claw" of the splint. Hence, that shan't be popping loose and out anytime soon.
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Out of a not-so-clear-and-blue sky, a splint of aluminum was born...
The inner areas, front and back, of the cowling were sanded where needed...
...then washed...
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Why are two of the plastic spider-stalks marked with blue painters' tape, and what's up with that wonky rule?
Plastic and aluminum go together like...
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...that through the bundled 10mm Kellner. I see a ghost, there in the centre of the Moon; a Moon ghost. I don't like Moon ghosts, or ghosts of any sort, or flares. I owe to that image my driving desire to make this telescope the best that it can ever be. On the other hand, via my Vixen NPL 30mm Plossl, at 13x, the view's lovely...
I did have the galaxy in Andromeda primarily in mind when I considered getting this telescope, and for a lowest power possible. I didn't want an 80mm f/5 achromat(identical focal-length), as I already have an 80mm f/6.
A few months later, in April 2017, I began to disassemble the telescope, and by renovating its wonky, plastic focusser. I got most of the wonkiness out, but it will require further tweaking before I may declare it done. Later, I removed the telescope's fixed dovetail-bar, and purchased a pair of tube-rings...
Almost $50 those rings had cost, and seemingly proprietary; "Antares" branded. But now I can twirl it round and about, upon this tripod-type mount and that. What do I not do for my telescopes.
But the very first thing that I did was to centre-spot the primary-mirror, as I was most curious as to how accurate the collimation was upon arrival, especially with the telescope's fixed, non-adjustable primary-cell...
The secondary-scene, before...
...and after...
Well, would you look at that. It was bang-on all the while.
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I had acquired this kit round Christmas, 2016....
It is practically identical to the Sky-Watcher "Heritage" 100P, and to where, quite likely, both were manufactured in the same factory overseas...
http://www.firstlightoptics.com/user/products/sw_heritage_100p.jpg
The Orion(of California) "SkyScanner" 100mm is actually more closely identical to the "Heritage" 100P. Hence, I look upon my own as the "dark horse" among the three. Incidentally, I chose this one due to its more traditional focusser placement; albeit due to its special price at the time of US$89.99/£73.16 in addition. It came with these two eyepieces, which differ slightly from those bundled with the other two...
The outside of the telescope can use a little work, but it's where the light enters and travels along that concerns me the most...
My, isn't that nice 'n' shiny? In addition, it has those three, wonderful, thick, plastic spider-stalks...
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It appears that the telescope needs to be moved forward a bit more within its rings. It's bottom-heavy within the video. The primary-mirror is located there at the back, and it accounts for a good deal of weight.
The telescope should be balanced on the DEC-axis with the axis at one side. At 3:48...
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For the Moon, and the planets as well, and perhaps the brighter of deep-sky objects, you would have greater success in using a webcam designed or modified for telescopes.
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14 hours ago, johninderby said:
No problem buying off eBay if you are buying from a proper dealers eBay shop or you could buy direct from their bricks and mortar shop.
http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_201
That star-mirror appears to be a good if not a great value. Incidentally, their eBay shipping-policy excludes Croatia, but not within their home website; odd, that.
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8 minutes ago, Ignoro said:
I'm in Croatia and seller is UK
just accidentally I put ebay.com, so you say he should get a prism but not the one from Starguider?
No, do not get that Starguider erect-image Amici-prism diagonal. The listing states, "We are delighted to offer for sale this Starguider 90 degree prismatic correct image star diagonal", and "Another consequence of using this particular diagonal is that the prism produces the image in the same orientation as seen by the eye and so it will be the right way up and the right way round."
That one would be no different from the one your friend has now. Again, both are primarily for daytime/terrestrial use.
I really cannot recommend ordering a diagonal off of eBay, especially if you're unsure about diagonals.
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1 hour ago, Ignoro said:
I looked through his scope a few days ago and didn't notice a line on planets.
Perhaps they weren't very bright at the time, but you'd eventually see it. Look here...
...that vertical line in the centre. If it's illuminated enough, it'll show up, like when Jupiter's riding high in the sky and shining bright. You'll see, and as I've seen it.
Star-diagonals have larger light-ports, and ideal for use at night when you need all the light you can get from an object. During the day, it doesn't matter if the port is small, like with those Amici, erect-image diagonals, for there's plenty of light with the Sun shining...
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27 minutes ago, johninderby said:
Better spending a little bit more for a reasonable quality mirror diagonal. This one has good build quality as well as a brass compression ring to clamp the eyepiece not just a screw. Not a high grade mirror in it but still up to the job.
https://agenaastro.com/gso-1-25-90-refractor-mirror-star-diagonal.html
The OP is in Croatia. Is his friend in the U.S.? He did list U.S.-based eBay listings within his post, however the seller is located in the UK.
EDIT: I see that you corrected that. Carry on.
Still, wouldn't a star-prism be more suitable for a longer-focus achromat?
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3 minutes ago, Ignoro said:
He'll be buying a BST starguider 8mm eyepiece, so maybe make just one order for 2 items from the same seller to save some shipping:
I looked through his scope a few days ago and didn't notice a line on planets.
I have a reflector so I'm unfamiliar with diagonals, is prism better then mirror? Would he see any difference in his scope?Thanks
No, that is not a star-prism diagonal within the first listing. Read the fine print below. It states "correct image", which means it won't be any different from the one he already has. That seller is "incorrect" in stating that it's a star-diagonal. I'll be contacting that seller.
The star-mirror diagonal within the second listing is a star-diagonal, and for use at night.
A star-prism is more durable, and for a lifetime. A star-mirror is more prone to arriving out of collimation, alignment. Also, mirrors scatter more light than a prism, resulting in a faint cloud of light surrounding brighter objects.
But if it has to be between those two, get the star-mirror, absolutely.
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I have the same erect-image diagonal that comes with that kit...
It's primarily for daytime/terrestrial use; birds in trees, ships at sea, that sort of thing, and during the day. It can be used at night, but on the brighter objects, such as Jupiter, an illuminated line generally appears streaking across the face of the planet...
What your friend needs for astronomical use, at night, is a STAR-diagonal. I searched online for a "bst Starguider prism diagonal", and came up empty, but here are some star-diagonals for examples...
A star-prism... https://www.astroshop.eu/diagonal-prisms/celestron-zenith-prism-90d-1-25-/p,7987
A star-mirror... https://www.astroshop.eu/diagonal-mirrors/omegon-mirror-star-diagonal-90d-1-25-/p,46713
There are many others out there, and at varying levels of quality and price-points. Simply ensure that the listing states "STAR" and "90°" within the description, and you can't go wrong.
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The ninth and most-recent light, on August 23rd...
I took the Bird out as soon as it became dark. First, I observed Jupiter for a spell...
Actually, all four moons were visible. That afocal shot is by no means indicative of what I saw. For the very first time ever, with any telescope, I saw the Great Red Spot. It was tiny, but there it was. I even saw it rather clearly with the bundled 4mm(!). I don't know what to think of this 4mm, save that I apparently got one where the lenses were well ground and polished. How is that possible given the usual reputation of these kit eyepieces? I guess I'll have to chalk it up to being 2019.
I then observed Saturn for a while...
Again, that afocal shot is by no means representative of the tack-sharp view I saw. Through the 4mm, the image only slightly softened, but not by much at all.
I then aimed the Bird at Ascella, and this time I snapped a shot...
That afocal-shot falls short a bit, however it does reveal the beautiful blue colour of the star; and no, I did not increase the saturation with my PC paint program.
I then disengaged the axes, popped in the GSO "Super View" 20mm, and scanned in the area right round the top of the "Teapot". It wasn't long before I spotted M28(I think, but I'm pretty sure); a lovely globular cluster. I did have to use averted vision to see the "diamonds" within, but not that far away from the cluster; almost adjacent thereby.
Despite my success with this particular sample, I still refuse to suggest or recommend a "Bird Jones" to those first starting out. FLO doesn't even carry this kit. Still, beginners are attracted to this kit for its low price and short, compact tube, although it does seem to be priced considerably higher in the UK. Perhaps that will help to keep it out of consideration as a first telescope among most beginners.
For the rest of us, who love to putter and tinker, if you're looking for what is essentially a Chinese finger-puzzle in the world of telescopes, and quite a respectable performer after the unravelling, then you've found it.
Thanks for looking.
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I've had this 8" pier-extension attached to my larger, GSO alt-azimuth for I don't know how long...
I thought it was about time to remove it, for a while at least...
There, that's better.
The eighth light, on August 20th...
At around 9:30 PM, I took the Bird out to face the music of the southern part of the sky. The primary objective was to observe Ascella, there at the bottom of the "handle" of the "Teapot" in Sagittarius. When I first ran across it, the star was out of focus, and as you would see when star-testing. What a lovely blue colour it was, and well-saturated, almost electric. With the Vixen 6mm NPL, at 167x, the Airy disc of the star was distinct, but only off and on as the star wasn't that far above the horizon. There would be no splitting of that tight triple with a 5" aperture, despite its lying only 88 light-years distant. The Voyager I mount, with its slow-motion controls and axis-locks, allowed me to combine the bundled 4mm Ramsden with my Antares 2x-barlow, and for 100x per inch of aperture: 500x, and to observe the star with minimal shaking compared to that of the smaller alt-azimuth. The star took 20 seconds to traverse the 4mm's field-of-view, which is quite a considerable TFOV for this particular eyepiece. My Tani 4mm orthoscopic can't hold a candle to that one in that regard.
Yes, it was a fuzzy blob, of course, but not as fuzzy as that would seem to imply. I led the star across the field several times, over and over, and did note a brighter core, at which point I patted myself upon the back.
Saturn was gorgeous, slightly swimming in the atmospheric chicken-broth at high power, but not that bad. I then brought out that Meade zoom that I've barely used, and continued to observe Saturn for a spell. This zoom isn't half-bad, not at all. As a matter of fact, as I was enjoying the practically tack-sharp view of the planet at the 8mm setting(125x), I could sense my dedicated oculars trembling yonder.
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The sixth light, on August 19th...
That was the ticket, to collimate it as I had before, and without the barlow/corrector in place. I knew that it wasn't possible with a laser-collimator, but now I know that it's not even possible with passive tools: my sight-tube and collimation-cap.
Indeed, the residual overcast left behind by the short storm earlier in the day had vanished.
The Moon through the Tani 20mm Erfle, and at 50x ...
I tried to get a good shot through the Vixen 6mm NPL Plossl, and at 167x, but it didn't turn out to my liking.
I used the shaky ES "Twilight Nano" mount for the event, as I was too lazy to haul out the Voyager I alt-azimuth.
The grand prize was realised when I viewed Polaris with the Vixen 6mm, and at 167x. If the lone spider-stalk contributed anything detrimental to what I saw, it was of little to no consequence. The seeing was off and on, and as the spherical-primary was acclimating to boot. I eventually saw glory, with the seeing going in and out still. The Airy disc presented itself regularly, and had a rather tight first-diffraction ring round it, with successive rings shimmering, dynamic, as they emanated from their host. Polaris Ab was positioned a little below and slightly to the right of Polaris A, the main star. Also, Ab did not disappear when staring directly at it. I observed the wonder for about fifteen minutes, as I had used lemon-eucalyptus spray instead of the deet-based. I could've stared at the star until dawn, as it was that beautiful; and also, because it doesn't move.
I tried my best to get an out-of-focus shot of the star, but to no avail. On the extra-focal side, I could see practically all of the rings, and with the outermost rings only slighter brighter than the rest; intra-focally, it wasn't quite as clear, yet it appeared identical nonetheless.
After everything was taken indoors, I processed the images of the Moon. Then, as I had been compelled and inspired to do by the sight, I made a virtual "sketch" of Polaris A and Ab, as I saw them, and with my PC paint program...
Dare I state that I now possess what is perhaps the finest Synta 127mm f/8 "Bird Jones" on the planet?
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Again, note the secondary off-setting...
Therefore, again, this is an f/3.3 to f/4 Newtonian, yet with a barlowing corrector/doublet, and for an effective focal-length of 1000mm. Despite the latter, the views at the lower powers are comatic, as is, albeit somewhat, evident at the edge of this eyepiece's field-of-view...
I have viewed clusters of stars at the lower powers with this telescope, and with the stars at the edge of the view as lines, streaks, and "teardrops". 1.25" coma-correctors are practically non-existent, which would nonetheless be required for this telescope at the lower powers; not to mention the extra expense, and for an entry-level kit. But then, the views on-axis are fine at same.
Still, the user would therefore be most comfortable and happiest in using this telescope for which it was designed and intended: for the medium, high, and highest powers.
In that, it excels.
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It is now known that in order to collimate a "Bird Jones" catadioptric-reflector, the corrector/doublet must be removed from the focusser's drawtube, and regardless of whether a laser-collimator or a passive-tool is used. I overwhelmingly prefer the passive-tools.
Through the sight-tube(or a modern Cheshire with cross-hairs), when the cross-hairs of the tool, the mirror-image of same, and the primary-mirror's centre-spot, all coincide...
...you're golden. I then inserted the collimation-cap, still without the doublet in place...
It was then that I was able to fine-tune the collimation further, as shown, and with the black-dot centred within the primary-mirror's centre-spot; just a slight tweaking. At that point, the doublet and its cell were reinstalled.
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In wanting to collimate the telescope more precisely, I did so with the corrector-doublet in place, erroneously thinking that it was not necessary to remove it when using passive tools; specifically, and more easily, with a collimation cap...
Afterwards, I took the telescope out. The Moon appeared...okay...at 50x...
...but Polaris, at 167x, flared off and outward to its left.
Back to the drawing-board...
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A 12" aperture gathers quite a bit of light, and perhaps too much for the brighter objects.
Get two of these...
https://www.bintel.com.au/product/bintel-gso-polariser-1-25-inch/?v=4442e4af0916
...and combine them for a variable-polariser. The filter acts as a dimmer for indoor-lighting, but for the telescope instead...
The filter will also reduce and even eliminate those pesky flares caused by the telescope's secondary spider-vanes.
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Would it be possible for you to post an image of the objective, like this...
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just accidentally I put ebay.com, so you say he should get a prism but not the one from Starguider?
Zhumell Z100 100mm f/4 Newtonian
in DIY Astronomer
Posted · Edited by Alan64
I had made the depressions for the plates a little too deep, so I then floated both with more epoxy...
The favoured stalk in toto, completed...
A silhouette...
Note how the favoured stalk overall had narrowed as the modification progressed; the thinner, the better.
The other two were then cut out...
In the end, I do have one of the hub's set-screw holes aligned with the focusser...
...and just as it should be...