Celestron PowerSeeker 127EQ Renovation

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Re: Celestron PowerSeeker 127EQ Renovation

#21

Post by Sky Tinker » Mon Dec 30, 2019 5:13 am

The two parts of the cell were sanded, masked-off, and matte-blackened where necessary...
primary cell15b.jpg
That looks like a birthday-cake, on Vulcan.

The other half; the other was also primed before blackening...
primary cell18c.jpg
The two parts completed, to a point. Gone is that glossy, reflective, hammered-black finish...
primary cell19.jpg
Hmm, I didn't paint right below the clips' posts...
primary cell20.jpg
Something special must be going there.

My late father dabbled in wood-working, and as I do as well. He left me this nice piece of English walnut...
primary supports4.jpg
That's actually a scrap from a larger board that I've already used, but all I needed was the tip...
primary supports.jpg
I made the new supports for the primary-mirror slightly smaller than the rubber ones.

They were shellacked...
cell blocks.jpg
...then epoxied into place...
primary cell blocks.jpg
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#22

Post by Sky Tinker » Mon Dec 30, 2019 5:28 am

I touched up the matte-black round and about the blocks...
primary cell blocks2.jpg
...and topped them with matte-black art-paper, using wood-glue...
primary supports9b.jpg
A few years ago, I ordered a square of leather, and for a mat for my Czech turntable...
turntable cover2.jpg
turntable cover2.jpg (14.99 KiB) Viewed 365 times
Analogue is still big over there, and seems to be experiencing a renaissance over here as well.

I don't throw anything away...
leather.jpg
leather.jpg (33.62 KiB) Viewed 365 times
Voilà...
primary supports10b.jpg
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#23

Post by Sky Tinker » Mon Dec 30, 2019 7:30 am

The primary-mirror resting upon its new digs...
primary mirror3.jpg
...and the backside of same. That's certainly a clean and clear blank of soda-lime plate. Hmm, let's see if we can get this right...
primary center-spot2.jpg
Nope.
primary center-spot3.jpg
Not a chance.
primary center-spot.jpg
Bingo!

I have read elsewhere that it's not necessary to center-spot a spherical primary-mirror. If it's a bit off-center, no problem, for it's a sphere. I understand that, but that should not be known to most, particularly those new and even intermediate to the pastime, as that can result in a parabola not being center-spotted. As I see it, the mirror is round, it has a center, and therefore it's going to have a center-spot.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#24

Post by Sky Tinker » Mon Dec 30, 2019 7:50 am

The primary-mirror also has a stoned edge, just a sliver, but an edge to be blackened nonetheless...
primary blackened5.jpg
Oh dear, I seem to have blackened it too much.
primary blackened7.jpg
Oh, that was just the reflection off of my monitor.
primary blackened.jpg
Glamour shot...
primary blackened2.jpg
See that little dot jutting into the reflective surface along the rim? That's where the edge was ever so slightly chipped somehow, and at the factory of course.

The mirror was then set aside...
primary mirror2.jpg
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#25

Post by Sky Tinker » Tue Dec 31, 2019 12:28 am

With the new blocks for the primary-mirror, particularly with the addition of the leather-pads, I had to make spacers for the retaining-clips, to raise them a bit higher...
clip spacers2.jpg
clip spacers2.jpg (28.73 KiB) Viewed 341 times
The clips' hardware was sanded and matte-blackened...
clips' hardware2b.jpg
After trial-and-error, I finally arrived at this clearance for all three clips round the mirror...
clips final.jpg
The primary-cell completed...
primary-no flash.jpg
I will need to blacken the tips of the adjustment-screws in future...
screw tips.jpg
I thought this interesting, and when the mirror was sitting in front of the monitor...
patterns.jpg
They appear as Ronchi patterns.

The primary-cell took only two layers of aluminum-foil tape, and for a snug fit onto the optical-tube.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#26

Post by Sky Tinker » Tue Dec 31, 2019 2:56 am

The dust-cap, and quite substantial for any telescope, at any price...
dust cap4b.jpg
Upon taking it into hand, I snapped off every last clip, and in less than a minute...
snap snap snap.jpg
I can't have those clips scratching up the matte-black finish of the inner rim of the cowling when the cap is inserted.

The wide tabs had their corners rounded and the tabs bevelled, then the inner side of the cap was sanded, including the aperture stop...
dust cap7c.jpg
The inner side and the aperture-stop's wall and forward-facing rim were matte-blackened. Also, the gap between two of the tabs was widened, and to easily accommodate the now-thicker, single stalk of the cowling...
dust cap8.jpg
Self-adhesive, hard, red-felt strips were attached to the tabs...
dust cap9.jpg
The cap fits perfectly; not too tight, nor too loose...
dust cap9b.jpg
For an improved seal, I applied a narrow strip of flocking all round the outer perimeter of the cap...
dust cap10.jpg
This is what I call the cap-keeper...
cap keeper.jpg
...and a rather poor one as it arrived, as the cap falls right off. So, I applied a strip of flocking halfway round the side; done.

The diameter of the aperture-stop is a "generous" 40mm, and if that wasn't bad enough, it's obstructed off to one side by the secondary-hub...
stopped aperture.jpg
The designer didn't have to make the hub over-sized, but it is what it is. In any event, that would be the near-equivalent to a 40mm f/25 achromat; joy joy.

Incidentally, you can see the head of one of the three secondary-hub's set-screws there. I had to abandon the socket-caps illustrated earlier, as they weren't threaded along their entire length, so I settled upon the button-socket type that were fully threaded. I can still adjust them with just my fingers, albeit with a bit more difficulty. In any event, I can replace them at any time.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#27

Post by Sky Tinker » Tue Dec 31, 2019 5:14 pm

Regrettably, I never took a photo of the kit upon arrival, but only after I had renovated both the OTA and the CG-2(EQ-1) mount...
OEM7.jpg
That's only a prop-shot, as the two will never "dance" together 'neath the celestial void. I can just hear the mount cracking asunder.
OEM3.jpg
I might shave by using the back of the mirror here...
OEM2b.jpg
OEM2b.jpg (15.9 KiB) Viewed 319 times
With the "naugahyde" plate removed, a rather large gap was left between the back of the mirror and the frame's opening. All manner and sorts of things could crawl or fly up into the tube.

The solution to that begins with this square of 100-mesh screen...
100-mesh.jpg
Also, that way I won't have to attach a shower-cap over the back when storing.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#28

Post by Sky Tinker » Tue Dec 31, 2019 6:11 pm

Three thin discs were made from a short stainless-steel, yet ferrous, rule, and epoxied to the frame...
neodymium7.jpg
In hindsight, I would have rather drilled holes into the frame and installed thick, steel plugs. I can do that in future, still.

Locally, all I can find are small neodymium magnets, but online I found larger and thicker ones...
neodymium9.jpg
The screen's frame was made from aluminum-sheet and thin plywood...
screen frame3.jpg
The larger magnets were epoxied into the plywood portion...
neodymium11.jpg
Both components were painted, or dyed, or primed, where necessary...
screen frame7e.jpg
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#29

Post by Sky Tinker » Tue Dec 31, 2019 6:40 pm

I used 5-minute epoxy, so I had to work fast...
screen frame7d.jpg
screen frame8.jpg
That, my great-grandmother's seven-pounder, made in Sheffield, England long ago; and underneath that, an old copy of Patrick Moore's "Amateur Astronomy", and to ensure the "feng shui" of the operation. At one point, I lifted the aforementioned off and inspected...
screen frame9.jpg
Looks good to me, then the book and iron had gone back onto it.
screen frame10.jpg
I finally got all the slivers of screen cut back to the outer edge of the frame...ouch. The screen was masked off, the black-dyed side of the plywood was clear-coated, and then the frame mounted onto a stand of my own creation...
stand7.jpg
The edge of the frame all round was sealed with a mixture of J-B Weld and sawdust, for a textured appearance, and in keeping with the final finish. Also, the last of those painful slivers of screen were entombed...
stand4b.jpg
The final finish? What else but that ubiquitous hammered-black, and for mail-boxes...
screen frame11.jpg
screen frame14b.jpg
screen frame14.jpg
The frame grabs onto the cell quite well. You can move and swing the telescope all round and it will not pop off. It's even self-centering to a degree. But if you bump it with the hand or an object, off it flies onto the floor or the ground.
screen frame12.jpg
With that, in so far as the physical aspects, the telescope was completed.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#30

Post by Sky Tinker » Wed Jan 01, 2020 3:56 am

To ensure success in collimating the telescope, and to where you will enjoy sharp, pleasing images at the higher and highest powers of which the telescope's aperture is capable, albeit partly to what the atmosphere will allow during a given observation, the following is strongly suggested...

1. Renovate the focusser to where the draw-tube racks in and out, true and square within its housing, and with no binding nor slop whatsoever. This applies to all telescopes actually, and regardless of design. You also have the option of cleaning the factory-grease from the rack and pinion, and replacing that with Super Lube, a high-quality, PTFE-based grease, to be applied sparingly.

2. Collimating the telescope, and the retention of same, is made that much easier if the rubber-grommets of the primary-cell are replaced with metal-springs.

Both aspects have been described and illustrated within this thread.

I have a laser-collimator. It's an inexpensive unit, although it did come with a triplet-lens for the laser, and for a sharper, tighter spot. My own arrived requiring collimation, as most do. I collimated it, and with a jig of my own design...
laser-collimator stand11a.jpg
laser-collimator stand11a.jpg (21.38 KiB) Viewed 302 times
However...
no laser collimator.jpg
no laser collimator.jpg (22.73 KiB) Viewed 302 times
I suppose they're fine for larger, longer Newtonians and Newtonian-Dobsons, and otherwise as a cat-toy, but definitely not for these smaller reflectors.

I prefer old-school, passive tools, like this Tectron sight-tube, with cross-hairs...
Tectron sight-tube2c.jpg
The modern incarnation combines a Cheshire with a sight-tube/cross-hairs; for example...

https://i.imgur.com/jyXjSoq.jpg

That type is readily available, and recommended.

I also use a collimation-cap, as a "second opinion". The cap also allows you watch whilst you batten down the adjustment-screws of either the secondary or primary mirrors, and to keep the alignment of either intact whilst so doing...
collimation cap.jpg
collimation cap.jpg (20.43 KiB) Viewed 302 times
That one came with my Orion "StarBlast 6"; a 6" f/5 Newtonian-Dobson, and a one-arm bandit. A collimation-cap can be purchased from Agena Astro of California, or First Light Optics in the UK, presently; or one can be made from the focusser's dust-cap...
focusser dust-cap2.jpg
focusser dust-cap2.jpg (10.59 KiB) Viewed 302 times
You simply drill a 2mm hole, with a 2mm drill-bit, as precisely in the center of the cap as possible, then line the underside with a circle of aluminum-foil, the dull or reflective side, take your pick. Try both.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#31

Post by Sky Tinker » Wed Jan 01, 2020 4:37 am

It's time to collimate the "Bird"...

The corrective, barlowing doublet-lens and its cell MUST be removed from the draw-tube in order to collimate this telescope. Again...
doublet9.jpg
...then reinstall the draw-tube.

I cover the top of a small table-lamp, with gift-tissue in this instance, and secured with a rubber-band. I then place the lamp in front of the tube, and to illuminate the collimation-scenes...
illumination.jpg
illumination.jpg (13.11 KiB) Viewed 299 times
With the sight-tube inserted, the secondary-mirror must be centered directly under the focusser, and appear as a perfect circle...
secondary mirror18c.jpg
secondary mirror18c.jpg (7 KiB) Viewed 299 times
Note: It helps to insert a piece of paper in between the two mirrors when aligning the secondary-mirror, to keep one from "seeing" the other. That is described here, and on the second page...

http://www.schlatter.org/Dad/Astronomy/collimate.htm

Other collimation-tutorials online may also be consulted.

Adjusting the secondary-mirror is accomplished with the four screws of the secondary-hub...
secondary hub.jpg
secondary hub.jpg (12.38 KiB) Viewed 299 times
The larger center-screw is spring-loaded, and moves the secondary-mirror back and forth along the axis, or length, of the telescope's optical tube. You want to move the mirror directly under the focusser with the center-screw. The mirror also rotates on the center-screw. The three smaller screws round the perimeter of the hub adjust the tilt of the mirror. The secondary-mirror can be rotated and tilted in every conceivable direction and position, but it must come to rest in only one position, with its center aligned with the center of the draw-tube of the focusser, and the centers of the secondary and primary mirrors; all together, in unison, and in a L-shaped path...
Newtonian light-path2ca.jpg
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#32

Post by Sky Tinker » Wed Jan 01, 2020 5:44 am

After the alignment of the secondary-mirror is completed, I then remove the paper separating the two mirrors, and begin tilting the primary-mirror towards the secondary. The sight-tube, or modern Cheshire with cross-hairs, is left inserted.

Back and forth between the mirrors I go, carefully and slowly adjusting the secondary, then the primary, then the secondary, then the primary, and until I see this...
sight tube - 081819d.jpg
sight tube - 081819d.jpg (19.12 KiB) Viewed 291 times
When you see the cross-hairs of the sight-tube lined up with the mirror-image of the cross-hairs(both in red), along with the center-spot of the primary-mirror(outlined in blue), you're golden...
sight tube - 081819c.jpg
sight tube - 081819c.jpg (22.51 KiB) Viewed 291 times
Note, there in the center, how the lighter circle(outlined in yellow) is not centered within the secondary-shadow(outlined in green). That is normal for a short, fast reflector, and at a native f/4(yet an effective f/8 with the doublet-lens in place). That is known as the secondary-offsetting, and it occurs automatically during a normal collimation procedure. There's nothing for the user to do to accomplish the off-setting.

I then insert a collimation-cap to verify...
collimation cap - 081819.jpg
...right on the money.

After collimating, return the doublet-lens and cell to the end of the draw-tube. To keep the collimation intact, and to keep from having to remove the doublet-lens frequently, be certain to tighten all of the adjustment-screws for both the secondary and primary mirrors, and whilst keeping the collimation intact. Whilst tightening the screws, observe the scene with the collimation-cap to make certain that nothing shifts out of alignment...

...and you're done.
Last edited by Sky Tinker on Wed Jan 01, 2020 6:06 am, edited 1 time in total.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#33

Post by notFritzArgelander » Wed Jan 01, 2020 5:46 am

Sky Tinker wrote:
Mon Dec 30, 2019 7:30 am
I have read elsewhere that it's not necessary to center-spot a spherical primary-mirror. If it's a bit off-center, no problem, for it's a sphere. I understand that, but that should not be known to most, particularly those new and even intermediate to the pastime, as that can result in a parabola not being center-spotted. As I see it, the mirror is round, it has a center, and therefore it's going to have a center-spot.
You're right to disbelieve that! It's only "not a problem" with perfect collimation. I like center spots.
Scopes: Refractors: Orion ST80, SV ED80 A f7; Newtonians: Z12 f5; Catadioptrics: VMC110L, Intes MK66. EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion Sirius EQG
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#34

Post by Sky Tinker » Wed Jan 01, 2020 6:03 am

Sky Tinker wrote:
Wed Jan 01, 2020 4:37 am
...with its center aligned with the center of the draw-tube of the focusser, and the centers of the secondary and primary mirrors...

Correction: ...with its center aligned with the center of the draw-tube of the focusser and the center of the primary mirror...
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#35

Post by notFritzArgelander » Wed Jan 01, 2020 6:17 am

Truly an epic makeover!

Your photos tell me that my recollection (posted earlier this week) that the "corrector" isn't a proper Jones-Bird optic but rather Barlow lens pressed into service was correct. The difference in thickness of the lenses in the doublet gives it away.

See the single doublet (3) in the figure under the heading "Conventional Barlow lens"
https://www.telescope-optics.net/miscel ... optics.htm

A double doublet is shown in the figure at the left with a single doublet to the right.

A true Jones-Bird has a doublet that is more equal. See figure 154.

https://www.telescope-optics.net/sub_ap ... htm#bottom
Scopes: Refractors: Orion ST80, SV ED80 A f7; Newtonians: Z12 f5; Catadioptrics: VMC110L, Intes MK66. EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion Sirius EQG
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#36

Post by Sky Tinker » Wed Jan 01, 2020 7:59 am

notFritzArgelander wrote:
Wed Jan 01, 2020 6:17 am
Truly an epic makeover!

Your photos tell me that my recollection (posted earlier this week) that the "corrector" isn't a proper Jones-Bird optic but rather Barlow lens pressed into service was correct. The difference in thickness of the lenses in the doublet gives it away.

See the single doublet (3) in the figure under the heading "Conventional Barlow lens"
https://www.telescope-optics.net/miscel ... optics.htm

A double doublet is shown in the figure at the left with a single doublet to the right.

A true Jones-Bird has a doublet that is more equal. See figure 154.

https://www.telescope-optics.net/sub_ap ... htm#bottom
I can't be certain if the doublet-lens does or does not correct for spherical-aberration until I observe and test further. The images I've seen after collimating have been great; other than comatic views at the lower powers, and in that it's behaving as an f/4 Newtonian should. Do you think it's possible that someone at the factory was having a good day and decided to go ahead and parabolise my mirror? Definitely stranger things have happened. Perhaps Synta is now parabolising all of them.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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#37

Post by notFritzArgelander » Wed Jan 01, 2020 8:13 am

Sky Tinker wrote:
Wed Jan 01, 2020 7:59 am
notFritzArgelander wrote:
Wed Jan 01, 2020 6:17 am
Truly an epic makeover!

Your photos tell me that my recollection (posted earlier this week) that the "corrector" isn't a proper Jones-Bird optic but rather Barlow lens pressed into service was correct. The difference in thickness of the lenses in the doublet gives it away.

See the single doublet (3) in the figure under the heading "Conventional Barlow lens"
https://www.telescope-optics.net/miscel ... optics.htm

A double doublet is shown in the figure at the left with a single doublet to the right.

A true Jones-Bird has a doublet that is more equal. See figure 154.

https://www.telescope-optics.net/sub_ap ... htm#bottom
I can't be certain if the doublet-lens does or does not correct for spherical-aberration until I observe and test further. The images I've seen after collimating have been great; other than comatic views at the lower powers, and in that it's behaving as an f/4 Newtonian should. Do you think it's possible that someone at the factory was having a good day and decided to go ahead and parabolise my mirror? Definitely stranger things have happened. Perhaps Synta is now parabolising all of them.
That would be one explanation. :shrug: I just don't know about that.

To evaluate expected coma https://www.telescope-optics.net/newton ... ations.htm

I would not rule out that you, yes YOU, did an outstanding job of rebuilding and permitted the optics to perform well.
Scopes: Refractors: Orion ST80, SV ED80 A f7; Newtonians: Z12 f5; Catadioptrics: VMC110L, Intes MK66. EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion Sirius EQG
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#38

Post by Lady Fraktor » Wed Jan 01, 2020 8:19 am

I would have to agree with nFA on that point, taking the time to correct the issues will make more of a difference than anything else.
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#39

Post by Michael131313 » Wed Jan 01, 2020 6:29 pm

Thanks very much for your thread. Fantastic job. I learned a lot.
ES AR 102 102mm, f/6.5, Orion Starblast 4.5 114mm,f/4 , Obie 10x50, GSO SV 30mm, ES 68° 20mm, ES 82° 14mm, 11mm, 8.8 mm, 6.8mm, 4.7mm. Twilight 1 mount.
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#40

Post by Sky Tinker » Wed Jan 01, 2020 7:45 pm

The one aspect that makes this type of telescope so attractive to those first starting out is, above all else, the low price. The short tube, and perhaps the larger aperture at that price-point, are also attractants. For some, it is all that they can afford, hence my interest in helping to make the ownership less of a burden and regret; to get it out under the sky, instead of using it as a decoration for the living-room. It does appear rather snazzy for the latter, but I digress.

For others, they do not wish to place a lot of money into a first telescope, for they're not certain if it will retain their interest. They, too, may benefit from a bit of guidance.

Decent and even very good performance may be had with these only if they're collimated well, that's all. Some kits do arrive well-collimated, as some reviewers attest. Consequently, they love the telescope. Some love it, others hate it, and it all boils down to the degree of collimation upon arrival. You have two strikes against that however: the plasticky, wonky focusser, and the rubber-grommets of the primary-cell. Then there's a third even: also having to remove the doublet-lens to collimate the telescope properly; no ifs, ands, or buts.

"That's too much work! Why bother with it at all???"

Three strikes, and it's out, for many.

For the experienced, however, the kit makes for an absolutely rewarding and wonderful puttering and tinkering about. But I wasn't about to transform this sow's ear into a silk purse(as it is now in fact) without sharing my experience, and in explaining how to simply make it worth the while, albeit if acquired by accident. That's why I purchased it in the first place, to help others; but no, not to promote it...
082019b.jpg
082019b.jpg (27.29 KiB) Viewed 240 times
For the brave and inquisitive, do not consider the kit for the mount. Do not consider the mount at all, unless you have smaller telescopes, like a 90mm Maksutov, or an 80mm f/5 achromat...
kit5b.jpg
...although smaller counterweights will be required.

No, get it only for the OTA itself, and have at it.
"Look, son! Up there!" His son shouted back, "I see it! What is it?" The father regaled, "The galaxy! Andromeda! Our origin, our destiny!" And so the boy was hooked, and for the rest of his natural life.

Alan

Apochromat: Takahashi FS-102 f/8 - Achromats: Meade "Polaris" 90mm f/10(flocked & blackened), Antares(GSO) 805 80mm f/6(flocked & blackened), Celestron(Synta) "AstroMaster" 70mm f/13(flocked & blackened), Sears(Towa) #4-6340 50mm f/12(flocked & blackened) - Newtonians: Orion(Synta) 6" f/5(flocked & blackened), Meade "Polaris" 114mm f/8, Zhumell(GSO) Z100 100mm f/4 - Catadioptrics: Explore Scientific(JOC) 127mm f/15 Maksutov-Cassegrain, Celestron "PowerSeeker" 127mm f/8 "Bird Jones" reflector(modified, flocked, blackened...& collimated!)...and mounts, eyepieces, barlows and diagonals.
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