Alan64

Check the focusser. You want it to rack in and out stiffly yet smoothly, square and true to the doublet-lens at the front, and with no binding or slop. The bearings for the draw-tube may need to be added to or replaced to effect an improvement. As a matter of course, I routinely re-do the spacers between the lens-elements of my achromats. I simply measure the thickness of the paper ones, and make new ones of aluminium-foil tape, like so... I also blacken the edges of the lenses. You must feel comfortable in so doing before attempting, however. In addition, the doublet may be too loose within its cell, or too tightly held. There is a retaining-ring that holds the lenses in place. It should not be tight against the lenses(pinching), nor backed off too much. I install the ring to where it comes to a dead-stop, gently touching the lenses, then I back the ring off a quarter of a turn. Afterwards, the lenses may rattle slightly when the tube is gently bumped or shaken, but no harm is done. This is an example of a refractor's retaining-ring... Barring all of that, you may have the option of exchanging or returning the telescope.

Hello Danya, I had no idea of your having replied until now. The 6" f/5 Newtonian's only advantage over the 4" f/8 fluorite refractor is that it's a bit brighter, is all. The refractor is considerably superior in all other aspects. Star-testing is most simple... https://popastro.com/documents/PA_jan-mar2009_p12-13_telescopetopics_startesting.pdf You can use hard, possibly woolen, thin felt strips for the draw-tube's bearings if PTFE is not available. There are other materials, more common plastics, that may be used as well. Some have even used plastic inserts within men's shirt-collars. The goal is to get the draw-tube to rack inward and outward straight and true, with no binding or slop. The condition of a focusser is just as important as the other parts whilst collimating.

My thread above, and kindly shared, details an EQ2-class mount. The CG3 is also an EQ2-class mount. Yes, the red-fibre washer goes towards the worm-gear, and the clear, plastic washer towards the RA setting-circle. The order is shown correctly within your image... "I notice that the RA clutch screw is eating into the shaft of the orange cog..." Do be careful there. This is the RA worm-gear of a CG2 that I received from Celestron. It is part of a scrap mount-head that was sent to me under warranty, but only for the RA worm-block... These worm-gears are of aluminium. The clamp-screws are of steel. Note how that one got chewed up as a result. You must have a buffer between the two, a short brass pin, or rod. This is from an EQ-1. The factory included a steel clamp-pin, but I replaced it with brass... You want brass rod, and slightly smaller in diameter than the threaded hole, instead. Your CG3 may not have come with steel clamp-pins, but you can add them, but of brass rather. They will protect, and prevent further damage to, the worm-gear. Simply smooth any damage present with sand-paper, then fine steel-wool. I use oil with the steel-wool, and for a very smooth finish.

That's just my one 150mm f/5 on an equatorial mount, and an alt-azimuth mount. The telescope is from an Orion "StarBlast 6" Newtonian-Dobson kit... I despised that one-arm Dobson mount, and still do. It's up in the attic, and until it rots. The Z130 kit's Newtonian comes with tube-rings and a dovetail-bar, ready to mount on a tripod-type mount in seconds, and something to consider in future if you get that kit. Understand that the lion's share of the outlay is for the telescope. That's what you're really after anyway. The Sky-Watcher "Explorer" 130P comes with an EQ-2 mount that just supports the telescope, but not ideally. That kit's 130mm f/5 Newtonian is essentially the same as that of the Z130. This is a Sky-Watcher 150P... https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ota.html But when considering that one, this one is actually the one to get... https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html

Since my last reply, one of the things I've been doing is anguishing over how to re-attach the plastic covers for the altitude/latitude axis... I didn't want to simply glue them back on, but I can't think of any other way. So, I've resigned myself to gluing them, but not with a hard-curing glue in case I need or want to pop them back off in future. Fortunately, the cover with the markings re-seats exactly as it was positioned before. Otherwise, the head has all or most of its other accoutrements attached... For two or three days I hunted, to no avail, but finally I found the 7-pounder of the two counter-weights that came with the old CG-4(EQ-3). It also came with a 4-pounder... Also shown is the 11-pounder that came with the new Meade head, just that one. Then, at the top, the 8.2-pounder that came with my old Vixen GP-DX head. I should be all set, and to mount most if not all of my telescopes onto the new EQ-5 head. I do wish I could find a 2-pounder. Perhaps I can get by without one lighter when mounting my smallest of telescopes. When I had gotten the Vixen GP-DX long ago, it came with at least that 8.2-pounder, if not a smaller one in addition. I can't remember. It probably didn't. But at the time, I did get these two 11-pounders in black, and now in rusty-black... I had gotten those two 11-pounders for mounting my 8" f/5 Newtonian, but the telescope was too large for the Vixen GP-DX in the end. I did use one of them with my 4" refractor however... The refractor does weigh about 11 to 12 lbs., so the two were well matched. The Vixen 8.2-pounder was re-discovered several years later, then cleaned and re-painted. But I'm planning to strip it, and paint it another colour, which will be seen within a future posting.

The marques, the names, don't mean so much. There are only very few companies in China that produce all of these mass-produced telescopes, and under this brand and that. For example, the Sky-Watcher "Heritage" 130P is the same as the AWB "OneSky" which is the same as the Bushnell "Ares"... The Zhumell Z130 is not a competitor so much, but simply of a differing, more traditional construction. Yea, indeed, the mirrors within all four were probably on the same parts-table at the same factory overseas at one point in time. Each type has its pros and cons, however I'm of the opinion now that perhaps the "Heritage" 130P would be the one to get. Incidentally, if you'd rather not fuss with collimating a Newtonian, a refractor or a Maksutov might be considered as well.

If you'd like a more solidly-constructed 130mm f/5 Newtonian... https://www.amazon.co.uk/Zhumell-ZHUS003-1-Altazimuth-Reflector-Telescope/dp/B07BRLSVWM/ref=sr_1_1?dchild=1&keywords=zhumell+z130&qid=1630954828&sr=8-1 In future, you can transfer either telescope to most any tripod-type mount; for examples... That's my 150mm f/5.

This is the Orion 127mm f/12 Maksutov, and sold separately... https://www.telescope.com/Orion/Orion-Apex-127mm-Maksutov-Cassegrain-Telescope/rc/2160/p/9825.uts However, it comes equipped with an Amici/corrected-image diagonal, for use during the day, as a spotting-scope; birds in trees, ships at sea, that sort of thing. Although, I strongly recommend a Celestron star-prism diagonal when using the telescope at night... https://agenaastro.com/celestron-1-25-telescope-star-diagonal.html The telescope itself, however, is essentially the same as the Sky-Watcher 127mm , but in the U.S. the Sky-Watcher comes with a 2" visual-back and a 2" star-diagonal. The word "star" says it all, and again, for use at night... https://www.bhphotovideo.com/c/product/1141693-REG/sky_watcher_s11520_127mm_maksutov_cassegrain_ota.html That would be one of the ones to get, among the 127mm offerings of the design. You can then place it onto the mount of your choice. Incidentally, I have a 127mm Maksutov myself... It's the same the Bresser sold in Europe. Its focal-length is a bit longer, at 1900mm versus 1500mm for the Orion and Sky-Watcher models. In the U.S., it is known as the Explore Scientific "First Light"... https://www.bhphotovideo.com/c/product/1291487-REG/explore_scientific_fl_mc1271900tn_firstlight_127mm_f_15_alt_az.html?ap=y&smp=y It has a smaller secondary-obstruction, always a plus, and a full 127mm aperture. The Orion and Sky-Watcher 127mm Maksutovs operate at about a 118-120mm aperture, not the full 127mm as advertised, and with a slightly larger obstruction. Those are two of three reasons why I chose the ES. But be forewarned, as a Maksutov is relatively blind under the night sky compared to other types of telescopes with its length and width, similarly. That is why you often see Maksutovs combined with a go-to mount. On a manual mount, you will need a good finder, to help the telescope to "see" better and find its way round the night sky.

Yes, I've read about that elsewhere, but I wouldn't know for certain until I experienced it myself. It's in the effort to transform a Maksutov into an "all rounder"; great success, or some?

I can't help but wonder just how practical that is, given the hole in the centre of a Maksutov's primary-mirror; perhaps an itty-bitty wider view, I've no idea.

A very good point was made earlier, in that you can mount a short, low-power, wide-field achromat, an ST102 or ST120 perhaps, on a AZ-GTi go-to mount as well. The combination of the Maksutov or a C6, and the short achromat, would cover the gamut of nightly observations, at quite low powers with the achromat, and at those quite high with the Maksutov or C6; the two telescopes mounted one at a time, of course. In the end, whichever telescope you choose, even a "Heritage" 130P or 150P Newtonian-Dobson, will be worlds away from the 70mm f/6 "TravelScope" in performance. Incidentally, I have this 70mm f/4.3 achromat... It's even shorter than your own. It was stopped down upon arrival, and to a 30mm f/10, but I've opened it back up to 70mm, and with its "rainbows". Your 70mm may be stopped down as well, to 40mm or so, possibly; something you can investigate and putter round with in future. I'll be using that 70mm as a finder for my Maksutov. Then, don't necessarily discount the "Heritage" 130P or 150P, and for considerably less outlay. One or the other may be just the thing to tide you over until what you're really after is readily available, price- and stock-wise.

This Sky-Watcher option has been available in the U.S. for a little while... https://www.bhphotovideo.com/c/product/1404590-REG/sky_watcher_s21130_skymax_127_az_gti_mount.html It can be operated manually as well, via its "Freedom Find" feature, but it does not come with a hand-controller; only wi-fi enabled for control with a "smartphone" and app. A hand-controller may be purchased separately, however.

Yes, you have the same mount, which enables the telescope to be used manually, in the event of battery, motor or computer failures; or, if simply wanting to observe free-style.

https://www.telescope.com/Orion-StarSeeker-IV-127mm-GoTo-Mak-Cass-with-Controller/p/113918.uts?ensembleId=422 That kit comes with or without a hand-controller, according to preference. Without the hand-controller, you would use a "smartphone" and an app to control the telescope. You can always accessorise the telescope later. I've always thought it prudent to get the best telescope or kit with the current budget, then to get extras down the line, over the following weeks, months and years. Don't consider a 5SE, as a 127mm Maksutov will slay it.

Try this method for collimating your telescope... https://garyseronik.com/no-tools-telescope-collimation/

For the time being, during these difficult times, consider a 127mm Maksutov. It's a solid design, tightly constructed, and compact; a bit of a grab-and-go in its own right. Then, when things settle down, in future, you can get a C6, or a larger C8 perhaps, with a larger mount to support it. A C6 is lighter in weight, with a somewhat shorter focal-length, and with an extra inch of aperture. But then, it has a larger secondary-obstruction, blocking a little more of the aperture, and not quite as sharp as a Maksutov. It is more of an ergonomic telescope, for comfort, and that over optical-quality, I'm afraid. I almost considered a C6 myself, but after careful and lengthy research, I chose a Maksutov instead. A C6 is like a day at the county-fair, and fleeting. A Maksutov, however, is like a home-baked supper, each and every day, throughout the year.

I've been tarrying about, elsewhere, I'm afraid; my apologies. I'd suggest a 9mm and a 12mm to go with the barlow... https://tejraj.com/gso-plossl-eyepieces.html

My thinnest self-adhesive felt, even with the plastic ribs round the inner rim obliterated, would be far too thick for this. I didn't even attempt it. Instead, I got my older paper-backed flocking and installed a strip of that. But it was a bit too thick as well, to my liking. My newest flocking is not paper-backed, hence thinner, but not by much. Still, I had no other choice... It's quite snug, although I expect it to loosen up a little over time, but not too much I hope. Thank goodness that's done.

Yes, but only after rather extensive sanding and grinding.

Isn't it lovely? Success; the next thing to do is to line the inner rim of the cap with flocking, and perhaps with aluminum tape as a substrate, depending. There were ridges round the inner rim of the cap, and were obliterated. I never did like plastic ridges taking up slack, in this instance, or as bearings in the case of draw-tube runs within focusser housings...

I couldn't describe the outermost circle right on the edge of the sheet, as this sheet is not quite squared, and it was not sawn but seemingly chopped out, as one or two of the edges are slightly bevelled... But there it is nonetheless. As to when it will be sawn out, that's anybody's guess, including my own.

Oh, if I'm careful in laying the spacer out on the sheet, I can probably get a total of three spacers out of it, in case mistakes are made.

Ah, we mustn't rush these things. I haven't even completed the mount yet. It will be a challenge in enabling the fitting of it, and perhaps a fun one. It has already been done, per a thread on CN. But I didn't care for the manner in which it was done. In any event, it was successful.

Another reason why not to re-glue the old spacer back together again is that there's another glued layer which was subjected to the heat, repeatedly, as well. It would've come apart before finishing up the grinding and sanding, and I did have a bit more to do. Life's too short for all of that... I've never had aluminum stock this thick before... It sits right at 3.07mm, according to the caliper. At that thickness, I won't have to radically adjust the date-dial of the polar-scope via its retaining-rings, like I would've with the old spacer; perhaps only very little or none at all. The old spacer sat at 3.37mm, incidentally.