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About Alan64

  • Rank
    Proto Star

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  • Interests
    ...astronomy, naturally.
  • Location
    Mid-South, U.S.
  1. https://www.rothervalleyoptics.co.uk/antares-variable-polarising-filter-125.html With a 200mm aperture, the Moon can be bright enough to bother some, if not many, and the polariser can certainly be used to dim it down. But its greatest use is in dimming down Jupiter and Mars, particularly Jupiter, to eliminate the diffraction spikes caused by the Newtonian's secondary-spider vanes, but also to improve the contrast to where the planet's features are more easily seen... Of course, as I understand, the planets are not in the most favourable positions for observing, but in future they will be once again, and you'll be ready.
  2. Yes, throw the RA-axis back to the 90° position on the latitude-scale, or as near as you can. On my EQ-2 I can throw it back to about 85°, which is better than nothing. A simple modification can be performed to throw it all the way back to 90°, if you'd like to know how... You can still use the slow-motions, the declination to an extent, and for an alt-azimuth. The counterweight should also be attached, and to balance that side of the mount... ...and there you are: up and down, and left to right.
  3. I once had a hardcover Cambridge atlas, but it was destroyed in a fire. I don't think it treated double-stars specifically. I'm almost certain it was more generalised. I did get a spiral-bound however, years ago, and thankfully still the first edition at the time...
  4. In the getting of the kit, you're after the telescope primarily. Suitable alt-azimuth mounts are more expensive, and less commonplace; my 90/900 on an older alt-azimuth... That doesn't make much sense, given that those first starting out overwhelmingly prefer an alt-azimuth. But it does make "sense" when you factor in marketing, and profit. You're going to get a good telescope, else word would get round and they wouldn't sell at all; but the mount, eyepieces, and accessories, are not necessarily going to match the telescope, ideally, not at those price-points. The EQ-1 and EQ-2, are the smallest of equatorials... Both can be placed into an alt-azimuth mode, and by simply throwing the RA-axis all the way back to the 90° position... All the controls and components that operate in equatorial mode will also function in alt-azimuth, including the counterweight. The EQ-1 and EQ-2 have been around for quite a long time, since the early 1960s at least... https://astromart.com/images/classifieds/16327/326641-1.jpg No sense in throwing away perfectly good molds. In the end, you would find that you would need to do what the rest of us do, and in the customisation of a kit. For example, this 70/900 achromat is woefully under-mounted upon an EQ-1, and as it had arrived... Instead, and improved...
  5. Within your first photo, I don't think that your camera was focussed properly, which is why the shadow appeared. Practice makes perfect, it is said.
  6. A bit odd that you reside in Munich(?), yet listed an item located in the U.S. In any event, the Celestron CG-3 is the same as the Sky-Watcher EQ-2... https://www.teleskop-express.de/shop/product_info.php/info/p417_Skywatcher-German-equatorial-mount-EQ2-with-field-tripod---special-offer--.html It's cheaper than a go-to mount. You can attach an inexpensive 9V-battery motor-drive to the RA-axis of the EQ-2 and automatically track any object... https://www.teleskop-express.de/shop/product_info.php/info/p395_Skywatcher-Tracking-motor-for-EQ-2-mount.html I would suggest a lithium battery given the coming winter. The mount can certainly be broken down for travelling. I don't know if it would fit into a backpack however, but if there's a will there might be a way. The mount would certainly support a 4" Maksutov. I have an EQ-2 myself, a Meade... Although, all the brandings and marques, including the CG-3, are made in China, and perhaps even at the same factory.
  7. I have a 90/900 achromat, and mounted upon an EQ-2... The achromat is rather under-mounted there, as the images do shake and wiggle a bit before settling, but not as badly as that might imply. At 45x, the Trapezium and its environs within Orion is nothing short of glorious. A 90/900 would be more versatile than a 102mm 600(or 660). Also, the longer the achromat, the less false-colour to be seen when viewing brighter objects. But there's one thing we know nothing about: the amount of light pollution where you'll be observing. If you observe beneath darker skies, a 90/900 will not disappoint.
  8. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    And now, the best for last: the doublet, of crown and flint glass... Marks were made for the spacers' replacement, and a mark to preserve a, albeit wishful, calculated rotational position of the elements. The oversized, to me, black-paper spacers were history as soon as I laid eyes upon them. They were also haphazardly-placed, one of them a good bit away from the edge... The spacers were replaced with those of foil; each spacer of two thicknesses of aluminum-foil tape, if I recall, and smaller of course. Here, the edges of the doublet's two elements have been blackened... Before and after, the doublet blackened and with its new spacers, at right... Notice how the doublet appears much less...there...almost invisible. That's the ticket. That's what you want. With the telescope reassembled, at last, the objective, before and after... I've observed with it a couple of times thus far. I'll put it this way... The Trapezoid and its environs, within Orion, at 45x with a 20mm 68°: the nebula appeared as an island, its well-defined ghostly "shores" dropping off into a jet-black "sea". I've simply never seen it that beautiful before, certainly not with my blackened and flocked 150mm f/5 Newtonian. If you had seen it with your own eyes, you'd immediately set to work upon your own telescope(s), I'd wager. That's all.
  9. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    The dew-shield was also flocked... With the entry-level telescopes, the dust-cap for the objective SNAPS into place, along with its reduced-aperture cap, at 65mm. I don't care for that. So, I cut off all the ridges and bumps from round both caps, and used the dew-shield's flocking to hold the main cap in place, and red felt to hold the 65mm aperture-cap in its place... Both caps now fit like a glove, hold in place, and with no snapping pressure or sounds. For the main cap to fit into the flocked dew-shield, I had to reduce its diameter somewhat, and test-fitting it after each short grinding session; mustn't take too much off... Certain areas of the main cap were blackened; round the 65mm aperture on the front, and for kicks, the entire backside... The 65mm aperture can certainly be practical from time to time, and for a 65mm f/14. Also, the textured front surface of the main cap was dulled with #0000 steel-wool. I just love working on junk components, and in making them better than they deserve.
  10. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    The plastic objective-cell, and the retaining-ring for the doublet; my, they certainly are shiny... The ring and a portion of the cell were blackened, after the surfaces were roughened... That's the only portion of the cell that required blackening. The dew-shield... One piece it is, and with its faux flange. I hate shiny black plastic, even when it isn't in the light-path. It looks cheap. So, I painted it a matte-nickel, and overcoated that with a clear-satin... The rim of the objective-cell was painted, too... The dew-shield friction-fits over the cell, but it wasn't tight enough to my liking, so I added three strips of flocking, in a triad, round about the inner surface of the dew-shield's flange, and it's now nice and snug.
  11. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    Once the fixed dovetail-bar was removed, how to mount it? Again, the diameter of the Meade's optical-tube is 80mm. I had gotten an Antares 805 80mm f/6 achromat from Canada about three years ago... ...and its tube is 80mm in diameter as well... ...a perfect fit. The two telescopes can share the same tube-rings. Now, I couldn't balance the Antares with a 2" diagonal and a 2 eyepiece with its rather short dovetail-bar. Around 2003, I had acquired this 13"-long bar, and for a failed mounting project for yet another telescope(I have 12 or 14 at present)... It's rather dated, but never used, until now... ...most versatile for both telescopes, and for every conceivable balancing requirement. Here it is on the Antares, and balanced with the 2" diagonal and eyepiece... It will be shown fitted onto the Meade 90mm f/10 towards the end of the thread.
  12. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    What's next, I wonder. Ah, the optical-tube, of course... Three baffles this achromat sports. There will be no flocking past the first baffle from the objective end, but that's probably all it needs anyway, given the length of the tube and where ordinary blackening will suffice. Here, the first run from the objective end has been flocked, and the remainder re-blackened... That was taken with the flash of the camera. Here, without the flash... At the time that image was taken, there were eleven light-bulbs on in the room; to stray light, deader than a proverbial door-nail. The fixed dovetail-bar was removed, and the threaded holes of the tube filled... The aperture of this achromat is 90mm, but the diameter of the tube is 80mm. Within its cell, the doublet is stepped off away from the end of the tube, enough I suppose to render the 90mm aperture intact, or at least most of it...
  13. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    The interior of the focusser's housing, before and after... The adjustable(via set-screws), black-plastic bearing-strip for the drawtube became the substrate for a .030"-thick self-adhesive strip of PTFE. The two bases for the fixed strips received two layers of aluminum-foil tape, a layer of clear double-sided tape, and a .020"-thick strip of PTFE, each... Before, there was considerable slop as the drawtube was racked inward and outward, even when racked fully inward; but no more, even when racked fully outward... The camera had a hard time taking a crisp image of that utterly dead interior, instead focussing on the knobs outside. The distance from the outer surface of the drawtube to the inner rim of the housing's flange is 18mm to 18.5mm, all round; although I've yet to check the overall collimation. Working with this metal focusser was an absolute pleasure, compared to the plastic ones in the past. As I went along, everything seemed to magically fall into place, and work perfectly.
  14. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    That older version, the 390 and 395, can make use of a Herschel wedge, for solar. With the plastic objective-cell of my own, that's not an option, I'm afraid. I'll have to make do with the lesser white-light solution, the film.
  15. Alan64

    Meade "Polaris" 90mm f/10 Achromat

    All of the imported telescopes, regardless of design, are works in progress. It's left to the end-users to finish them up. Incidentally, in the early '90s, I had the misfortune of receiving a brand-new Meade 390 alt-azimuth kit. The doublet was fouled with dirt, and cracked even if I remember correctly. I sent it back pronto and got something else. However, this 90mm Meade is its antithesis, although the old Meade 90mm did sport a metal objective-cell.

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