Alan64

Laser-collimators are generally used for larger and longer Newtonians on Dobson mounts. The cheaper lasers usualy have to be collimated first, and can be more trouble than they're worth. I have one myself, and it is difficult to collimate, and before I can use it for a telescope. In any event, I don't use one to collimate my smaller, shorter Newtonians, like your own. Instead, I use a Cheshire and a collimation-cap, both, and during a single procedure. Cheshire... https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html Beware of cheaper Cheshires, as the cross-hairs may not be aligned correctly, and cannot be corrected. Collimation-cap... https://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html In the case of Newtonians, the peep-hole and cross-hairs of a Cheshire act as those of a sight-tube, and aid in centring the secondary-mirror directly under the draw-tube of the focusser... Then, adjusting both mirrors, you direct their centres towards each other, back and forth until they are aligned... When the cross-hairs of the Cheshire on the outside are aligned with the mirror-image of same in the centre, and both along with the primary-mirror's centre-spot, you're golden. I then use a collimation-cap to verify, and tweak further if necessary... When tightening down the primary's lock-bolts after adjustment, the cap allows you to keep an eye on the alignment to ensure that nothing shifts out of position when tightening. Note how the lighter circle is not centred within the larger black circle. It's askew, off-centre. That is normal for a short Newtonian(f/4, f/5). It is known as the secondary off-setting, and it occurs during a normal collimation procedure. There's nothing you have to do to accomplish the off-setting. Newtonian collimation tutorials... http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/ https://garyseronik.com/a-beginners-guide-to-collimation/

Your CG-3 equatorial mount is an EQ-2. I have a Meade, "Large Equatorial" they call it, and also an EQ-2. Here's my thread on its renovation... https://stargazerslounge.com/topic/319273-meade-large-equatorialeq-2-hyper-tuning/ Now, you're not expected to do everything I did. Just pick and choose according to your ability. You may not be able to access the lock-nut of the RA-axis with a socket-wrench, to free it up if it seems too tight. I had to use a larger pair of needle-nose pliers; heavy-duty, and to adjust or remove the nut. I don't have a 130/650, but I do have this 127/1000 "Bird Jones"... https://stargazerslounge.com/topic/340294-celestron-powerseeker-127eq/ You might be able to glean some help from that.

Yes, I had to use needle-nosed pliers, the heavy-duty type. A pair of those will make it a breeze. The lock-nut is not difficult to turn.

In addition, I would place a protective drape over it, perhaps a smaller plastic tarp or other.

I've always held dear within my heart and mind that the best EQ-3, is an EQ-5.

The thing I found most interesting within that was that you, somehow, some way, ended up with the exact same mount as the OP's, yet continents apart. It's nigh incredible, for that's the first time I've ever seen one.

Well, with the rings left on the OTA, they don't add that much more when storing same. But if you leave the rings on the mount, that can be quite a different storage problem, not to mention the risk of the rings getting torn up in the process.

I don't think you could find a used CG-4 there in the UK, cheaply in any event, as most tend to go with the Sky-Watcher variants.

Oh, you want to ensure that the RA-axis, its gear and worm, rotate freely and butter-smooth, with no slop or binding, before you use the motor-drive with it. Given the mount's age, I would suggest a take-apart of the mount-head, both the RA and DEC axes, for a thorough cleaning and removal of the old factory-grease, and to replace that with new grease, like Super Lube. Also, it may help to polish all of the bearing surfaces. I use #0000 steel-wool and a light machine-oil for that, but only if you encounter any rough surfaces.

And there upon the Acropolis, poised, albeit not so humbly, upon the steps of the Parthenon; and with Plato and Aristotle just within earshot... A flat bar, of aluminum or steel, or a dovetail-bar even, and attached to the existing saddle in place of the rings, like so... To rise to the level of the higher edges of the saddle, or just slightly above... ...the bar may need to be shimmed at the ends, like so... ...the shims of wood, preferably of oak or walnut. The Vixen-type saddle would then be attached to the center of the bar. Some basic measurements would be required, but just that, basic. The original saddle would remain intact, no holes to be drilled into it, as if you'd want to preserve such an archaic interface in the first place.

Hi Neil, In case you didn't notice it within your other thread... https://www.harrisontelescopes.co.uk/acatalog/revelation-dovetail-mount.html#SID=1718

That will be most interesting.

Hi Neil, Your new mount is an EQ-3, and appears to have the same old-style mounting-interface as that of your "PowerSeeker" CG-2. I have a CG-2 as well, and I had replaced that interface with a Vixen-type. My Celestron CG-4 is an EQ-3, but with tubular-steel legs instead of those of aluminum. I don't care for the steel legs myself. It came with a Vixen-type interface... https://www.harrisontelescopes.co.uk/acatalog/revelation-dovetail-mount.html#SID=1718 Wilcox-rings... http://www.andysshotglass.com/wilcox_rotating_rings.html You can also use a spare tube-ring to effect that. You would have to add Teflon to it, and to slide against one of the rings holding the telescope. Congratulations on your find. Keep looking up, and clear skies to you always.

A Herschel-wedge can be used with a refractor only, preferably a doublet. Also, the focusser, including the draw-tube, and the objective-cell retaining the doublet-lens at the front of the tube, and perhaps the dew-shield even, should all be of metal. All of the entry-level refractors coming out of China nowadays come with plastic objective-cells, and quite a few come with plastic focussers and draw-tubes. For those who disagree, do so at the telescope's risk.

What type of telescope would you be using on the mount?

https://www.firstlightoptics.com/alt-azimuth/sky-watcher-az-pronto-alt-azimuth-mount-tripod.html

The Moon, at 33x through the 12mm Konig... Now, it was at freezing, I was using the original mount, with my old(2002) Minolta point-and-shoot, and with the shutter at 1/30th or 1/45th of a second. I did have to brighten the image to match what I saw during the live view. I never enhance these afocal-shots otherwise, never have, as that would be dishonest. During the live view I saw Earth-shine on the left side, but this old camera couldn't pick it up.

I do know now that the telescope is collimated quite well. Sirius, extra-focally, and through a 12mm 60° Konig(33x)... I then observed the star with this, my SR4mm(100x) from my Celestron 127mm f/8 "Bird Jones" kit... The star was tight, yet as expected somewhat colourful due to the type of eyepiece. Afterwards, I used the 12mm to zero in on the Trapezium within Orion, then popped in the 4mm. I could just see the main stars, and sharply as well. It was difficult however to find the sweet-spot of sharpness as I racked back and forth.

A variable-polariser is only good for what was discussed; specific, and of limited use. I would go with the 1.25".

For better, or for worse, and through a collimation-cap... All I need now is a clear, night sky, and that will come in a day or two, but it's going to cold, cold, cold outdoors. But I won't need to be out there long. I hope the Moon will be out. I tried to use my Cheshire initially, but I don't think that it likes the visual-back of this telescope. I'll need to investigate that further, for it seemed to work well enough when I took this shot three years ago... Then this, the view through the collimation-cap three years ago... I did tweak the off-setting of the secondary-mirror in relation to its stalk during the renovation. Oh well, time will tell.

That, sir, is an excellent question. I am impressed. You wouldn't want a Lumicon? https://www.robtics.nl/product_info.php?products_id=4993&pID=4993&language=en That one is regarded as the finest on the planet. My Orion(of California) v-p was made in Japan, too, many years ago. But there are economical alternatives. House/Generic brands... https://www.firstlightoptics.com/moon-neutral-density-filters/astro-essentials-variable-polarising-moon-filter.html https://www.365astronomy.com/365astronomy-variable-polarising-filter-1.25-inch.html https://www.rothervalleyoptics.co.uk/ovl-variable-polarising-filters.html Name-brands... https://www.rothervalleyoptics.co.uk/antares-variable-polarising-filter-125.html https://www.rothervalleyoptics.co.uk/celestron-variable-polarizing-filter-125.html ...new product Two of the these GSO filters to purchase and to screw together for a v-p... https://www.365astronomy.com/Polarisation-filter-with-30-transmission-level-1.25-inch-M28-5X0.6.html Orion(of California) still offers a v-p, but it's not made in Japan as my Orion was many years ago. Per your question as to the performance of a cheaper one, I cannot say.

I'm afraid that the importance of a spot-on collimation cannot be over-emphasised. Do you know what a drill-sergeant is? This, my own variable-polariser... It simply dims down the light collected by the objective of the telescope. You still get the resolution of an 8", but there are times when you need to dim it down a bit. With my 6" f/5, the v-p eliminates the diffraction-effects of the secondary spider-vanes... Mars through my 6", during its last opposition, before and after... It also helps to detect the Moon-like phases of Venus. I don't think that Saturn would benefit from it, however.

I had this 70mm f/13 achromat... ...up to 225x one night, aimed at Polaris, the north star. I could still make out the star's Airy disc, and its first and subsequent diffraction-rings; not quite as sharply as at 150x, but it was certainly not so-called "empty magnification", not at all. It can be the atmosphere, and the state of the telescope's collimation, in keeping you from making good, practical use of the 5.5mm(218x). We are at the mercy of the atmosphere, but we don't have to be at the mercy of a telescope's level of collimation.

Per the old measurements, your 200P is capable of at least 50x per inch. Your telescope is an 8"... 8" x 50x = 400x That's the standard for Newtonians, 50x per inch before image-breakdown. But that is only possible under ideal atmospheric seeing conditions. Also, the collimation must be spot-on. Any telescope has to work harder at the higher and highest powers, therefore everything must be in order. Fine refractors, however, are known to reach 100x per inch. Under ideal atmospheric seeing conditions, my 4" refractor can reach 400x, but it would need to be on a motorised mount for a good look-see at whichever object I'd be observing at the time; most likely the Trapezium within the Orion nebula, at this time of year. The eyepieces and barlows also need to be of better quality. If you want to see what few people have ever seen, you're going to have to embrace, love, collimating; obsess over it even. When the planets come round again in a couple of years or so, you're going to want to see those at the higher powers. I guarantee it, and for that you may want a variable-polariser...

One thing that I've learned over time is that if you don't push the magnification up then you will never know how truly capable a telescope may be in fact, and in showing the user that which few people have ever seen. Never say never. That applies to all telescopes, including your 200P. I recently got this refractive equivalent to your nephew's reflector... ...a 70mm f4.3 achromat, also with a 300mm focal-length. I haven't pushed it to its limits quite yet, as I've got to blacken and flock it first, but I do have high hopes, high-powered hopes, and when I insert the eyepiece/barlow equivalent of a 1.5mm(200x) into it.