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Alan64

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  1. I've had Synta's base-model 150mm f/5 Newtonian, an Orion-branded "StarBlast 6", since the fall of 2012. I didn't start using it much until a couple of years later. Since that time I've enjoyed it quite a bit, and eventually flocked and blackened the interior of the optical-tube. The particle-board mount that came with it had been long since abandoned, up in the attic now where it will remain until it rots, my preferring instead a tripod-type alt-azimuth for the Newtonian. There was only one thing left to do: enable the focusser's drawtube to rack in and out, smoothly, straight and true, and for an exacting collimation and the best images the parabola might produce. Until yesterday, whilst somewhat satisfactory, I did not have a focusser quite up to par. The problem all along was with these, and what I call "coffee-cake tray-liners", or for packaged cinnamon rolls, albeit of plastic instead of paper, and for the drawtube to glide against... I could actually see the wonky path the drawtube took as it was racked in and out. The rest of the telescope is somewhat first-rate, particularly the primary-mirror cell and the secondary's spider-assembly. The parabola of the primary isn't bad either, not at all, with my having witnessed snap-to focussing at high-power on at least one occasion, with slightly above-average oculars, and with a 3x barlow integrated to boot. During my initial attempts to fix the focusser, I ended up spoiling the original plastic drawtube. Then a year ago I was able to get a replacement, but only by being the original purchaser. A real stickler for that they are, Orion in California... I gave the inside of the replacement a fresh spritzing from my rattle-can of ultra-flat black, then I prepped the outside for more... ...but in satin-black. I didn't want a chromed end jutting into the light-path. That step is optional, of course, but the next is not, I daresay... PTFE, or Teflon®, sheets, and of varying thicknesses... For this step, I chose the 0.020" or 0.508mm thick sheet. The materials used: said PTFE in three 3/4" or 19.05mm wide strips, double-sided transparent tape 1/2" or 12.7mm wide, and aluminum-foil tape(perhaps 0.0025" or 0.0635mm thick, and the strips cut to the same width as the PTFE)... First, the interior of the focusser's housing was degreased with 91% rubbing-alcohol. I then applied the three strips of aluminum tape in a triad around the drawtube's cavity, then the double-sided tape, then the three strips of PTFE... Both the aluminum tape and PTFE should be degreased as well, after handling with the fingers, and before and after applying the double-sided tape, respectively. The drawtube now racks in and out smoothly, straight and true, and with no discernible slop...at long last. Incidentally, the PTFE will lift right up off the double-sided tape, easily, but pulling on it parallel to the tape exhibits the opposite effect: it will not budge in the slightest. The visual-back of my own is not 1.25", but 1.255" or so. I lined the inside with a strip of the aluminum tape, and now it's quite close to the ideal, and a snug fit for my eyepieces and other accessories... I stopped just short of extending the tape past the two holes for the locking screws, then pressed and burnished the tape down. This fix is for all imported plastic focussers of overseas manufacture, whether for a Newtonian or refractor. Would that, one day, it would not need to be so.
  2. Yes, a 12mm Plossl is not bad, not bad at all. You may not want to go with anything shorter that a 10mm however, like an 8mm, 6mm or even a 4mm, as the eye-relief will be tighter and where you'd almost have to touch your eyeball to the field-lens of the eyepiece in order to see the full field-of-view.
  3. That one may just screw onto the visual-back, and without having to get this, and as I had mentioned before... https://www.telescopehouse.com/accessories/meade-lx/meade-sct-thread-to-2-adapter.html You would need that adaptor, however, if you got a standard push-fit 2" diagonal. It's best to build up an eventual set of eyepieces, one or two at a time. The quality of a barlow is just as important as that of an eyepiece. Don't get the cheapest ones that you can scrounge up, but you don't have to break the Bank of England, either.
  4. Were you able to determine that you can in fact connect a 2" diagonal to the telescope? You will need a specialised adaptor to connect one, if one is not already fitted... https://www.telescopehouse.com/accessories/meade-lx/meade-sct-thread-to-2-adapter.html The goal of upgrading to the 2" format is in realising the lowest powers with the telescope. For example, you can insert this 2" 56mm ocular for one of the lowest powers with your telescope... https://www.harrisontelescopes.co.uk/acatalog/Meade_Series_4000_56mm_Super_Plossl_Eyepiece_2_.html (36x) That's why owners of Schmidt-Cassegrains outfit them with a 2" visual-back, for the lowest powers. At the moderate-to-high powers, the 1.25" format is generally preferred. An 8mm ocular will give a power of 250x... http://www.365astronomy.com/8mm-the-planetary-uwa-eyepiece-58-degrees-1.25.html You can back off the power a bit with a 9mm... http://www.365astronomy.com/9mm-the-planetary-uwa-eyepiece-58-degrees-1.25.html (222x) ...if the atmospheric seeing will not permit 250x. Or, you can go with a 12mm... http://www.365astronomy.com/12mm-BST-Explorer-ED-Eyepiece.html (167x) The Moon and planets show considerable detail at 167x. You might wonder as to why Schmidts are not equipped with 2" visual-backs there at the factory, when they're new. The reason is simple... The hole in the center of a 200mm Schmidt's primary mirror, and through which the light from the object passes, is not 2" in diameter. It's more like 1.5", and ample for the 1.25" format. The inside of a Schmidt-Cassegrain... But given that extra 0.25" of the hole's diameter, 2" eyepieces can be used to make use of that extra bit, and for the lowest powers and the widest views that 2" oculars can provide with the design. You won't get the full view of a 2", like you would with a Newtonian or refractor, but you will get more than what a 1.25" 32mm or 40mm ocular can provide, and even lower powers in addition. It's a compromise, and simply to make a Schmidt more versatile. As a Schmidt comes from the factory, it is primarily configured for the moderate-to-high powers, and with the 1.25" format. I think that many users simply stick with the 1.25" format, aside from the more adventurous.
  5. For the record, when observing at night, it makes no difference if the images are backward or upside-down, therefore always use a star-diagonal at night. Now, you can use an Amici at night, but the view may be narrower, in addition to seeing what is known as an "Amici line" when viewing brighter objects...
  6. Another question? No problem at all. You've come to the right place. Your 200mm Schmidt has a focal-length of 2000mm, and is considered a "slow" telescope, at its f/10 focal-ratio. The nice thing about telescopes with slower focal-ratios is that most any inexpensive eyepiece will work very well and provide pleasing views. For the 1.25" format, a 32mm ocular would afford one of the lowest powers practical... 2000mm ÷ 32mm = a power of 63x; a 40mm: 50x, and the very lowest power available in the 1.25" format... http://www.365astronomy.com/32mm-GSO-Plossl-Eyepiece.html http://www.365astronomy.com/40mm-GSO-Plossl-Eyepiece.html Vixen makes very good Plossls... https://www.firstlightoptics.com/vixen-eyepieces/vixen-npl-eyepieces.html I have the Vixen 6mm and 30mm... The 30mm's field-lens is extraordinarily-large, and through which to look. The Antares Plossl line-up... http://www.rothervalleyoptics.co.uk/antares-plossl-eyepieces-125.html But where a Cassegrain really puts forth lies at the moderate-to-high powers. On most nights, you can use an 8mm... 2000mm ÷ 8mm = 250x, and for the Moon, the planets, and double-stars... http://www.365astronomy.com/8mm-the-planetary-uwa-eyepiece-58-degrees-1.25.html This 9mm(222x) has a somewhat wider field-of-view... http://www.365astronomy.com/TS-Ultra-Wide-Angle-Eyepiece-9mm-1.25-66o-with-Improved-Coating.html If you can wait on the boat, and do without the chromed barrel, this is the same eyepiece... http://www.ebay.co.uk/itm/1-25-31-7mm-Ultra-Wide-Angle-9mm-Eyepiece-Lens-66-Deg-for-Telescope-Best-track-/152129833857?hash=item236ba50b81:g:G8wAAOSwAuNW3lNp Incidentally, you do not have to purchase eyepieces and accessories of the same brand as the telescope. I've encountered some who think that you do, that they must match, but that is incorrect. Any brand of telescope may use any brand of eyepiece or accessory. For a relatively-moderate power, something in the 16mm+/- range would do nicely. Avoid eyepiece sets, such as these... https://www.harrisontelescopes.co.uk/acatalog/795.jpg https://www.harrisontelescopes.co.uk/acatalog/celestronepkit.jpg https://www.harrisontelescopes.co.uk/acatalog/series4000set.jpg https://images-na.ssl-images-amazon.com/images/I/51YYSxbn9IL._SY355_.jpg It's best, rather, to put together a set over time -- over the weeks, the months, and the years even -- and tailored to your observing habits. Always give careful thought to what is placed between the eye and the sky at night, and for best results.
  7. Very good; then what you need, for use at night, is a 90° STAR diagonal. You can choose either a prism-type or a mirror-type. A quality prism-type is more costly. Synta of China equips their current line-up of Schmidt-Cassegrains with this inexpensive prism star-diagonal... http://www.rothervalleyoptics.co.uk/celestron-90-degree-star-diagonal-125.html I have one, and it's quite good, especially for the low price... I've used that diagonal with a Celestron C90 90mm Maksutov, which is similar in design to your Schmidt-Cassegrain, and I'm pleased with the views; no complaints here. Others have had less-than-stellar experiences with it, and I attribute that to the lack of quality-control at the factory there in China. Alternatively, and unfortunately, the next step up in a prism is bit more costly... http://www.rothervalleyoptics.co.uk/baader-prism-diagonal-t-2-90-degree-32mm.html That's just the prism and body, which requires an eyepiece-holder and nosepiece to complete it... http://www.rothervalleyoptics.co.uk/baader-125-helical-focusing-eyepiece-holder-t2.html http://www.rothervalleyoptics.co.uk/baader-nosepiece-125-t2.html You'd never need another, unless you get a fast refractor in future to complement the Schmidt -- for low-power, wide-field, binocular-like views -- in which case you'd want a mirror-type. In so far as the prism-types available, indeed, in so far as all things man-made, it all depends on the level of quality desired. The mirror-types are more plentiful due to the ease in their manufacture, and consequently permeate the marketplace... http://www.rothervalleyoptics.co.uk/altair-astro-125-dielectric-star-diagonal.html Now, if you'd like to use your telescope during the day, for viewing land targets, birds, or other, you would want either a 45° or 90° AMICI(erect-image) diagonal... http://www.rothervalleyoptics.co.uk/antares-45-erecting-prism-125.html http://www.rothervalleyoptics.co.uk/antares-90-erecting-prism-125.html This is what a 45° Amici looks like(left)... The 45° would be comfortable for viewing land targets close to the ground, whilst the 90° would be more comfortable for viewing objects higher up, like a mountain top or the top of a tall tree nearby. If your visual-back might accommodate, and for use at night... http://www.rothervalleyoptics.co.uk/altair-2-dielectric-diagonal-99-quartz-push-fit.html ...then to use 2" eyepieces and accessories.
  8. Ah, a 200mm Schmidt; I thought so. That looks to be a very nice kit, indeed. You have several options for a 90° star-diagonal, and for use at night. During the day, for land targets, there are also 45° Amici-diagonals available. But we'll need to see an image of your visual-back, there at the rear of the telescope, like this... Are you able to insert a diagonal into the v-b, then tighten the screws to hold it; or do you need one that screws onto the v-b, which is common with that type of telescope? This is an example of one that screws onto the v-b... https://www.astronomics.com/images/Product/large/11608.jpg ...and in comparison to the standard type... Also, when you say "horizontal prism", are you referring to the kind that's used during the day, for corrected, upright images? If so, that's an Amici, or erect-image, diagonal.
  9. Hello Jimmy, and welcome. Please post a nice clear pic of the kit, and to help us to help you, like this... Or, locate the specs label on the telescope itself, and list its information here. I'm thinking that it's a 150mm or 200mm Schmidt-Cassegrain. If it is, then Schmidts do require collimating, alignment of the optics inside, especially in that it's used. That may be part of the problem. The optics could be fouled as well, and that would result in less-than-stellar images. "LX90" refers to the mount, not to the telescope primarily, so we'll need some more information. Cheers.
  10. Iain, that's a very if not extremely good afocal snap with a phone-camera. Feel free to ramp the power up to 200x and beyond when observing the Moon. I took this shot at almost 200x with my 150mm f/5... Congratulations on the new kit!
  11. Your Newtonian is a 130mm f/7, therefore the secondary off-set is not going to be that apparent at f/7. Note the off-set here with my 150mm f/5, on the right... On the left, an f/4, and even faster, therefore the greater the off-set. Fortunately, the off-set occurs automatically during a normal collimation procedure, and does not require a separate step to perform. Once you get the collimation-cap, and a Cheshire too, hopefully... https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html ...then, you can insert the collimation-cap where an eyepiece normally goes, aim the telescope at a white, blank, illuminated wall or other, place a small camera over the pinhole of the cap, zoom in if needed, snap a shot of the scene as I have many times, then post it here for us to have a look. The collimation-cap allows you see the entire optical system inside at a glance. Incidentally, a secondary off-set is to ensure that all of the light collected by the primary mirror reaches the eye. But, again, there will not be much of an off-set with your f/7 Newtonian after a proper collimation with the cap, and the Cheshire... A Cheshire is useful for for centering the secondary mirror directly under the focusser... The secondary mirror must also appear perfectly round, as a circle, or very near to it, as shown. A Cheshire also serves to ensure that the center of the eyepiece is aimed directly at the center-spot of the primary mirror... I look forward to seeing a nice snapshot of your secondary scene. Cheers,
  12. I don't know if 'twill or not. It's embedded within an Italian website(.it). I just discovered it recently, within the last month I think.
  13. Dave, is this what you're looking for... http://www.forumskylive.it/Public/data/serastrof/201281510358_Astro Babys Guide to Collimation.pdf
  14. I recently center-spotted the primary mirror of my 100mm f/4 tabletop. All you need is several sheets of white copy paper, a compass, transparent-tape, a permanent marker and a polyvinyl(or paper) notebook reinforcement. I made several patterns, and finally decided on one that would show just a sliver of the mirror all the way around... The pattern must be cut as perfectly as possible. The sharp compass-point produces the center point, and I enlarged the point's hole only slightly to effectively mark it with a permanent marker... I then took one of my discarded patterns and made a sizeable hole in the center. Next, I placed a narrow strip of tape across the hole and lightly adhered the top of the reinforcement to the underside of the tape, then laid the pattern over the mirror, centered the reinforcement over the mark and pressed it down, then peeled off the pattern and tape... I then cleaned the mark away with a cotton swab. It worked like a charm... The secondary scene as viewed through a collimation-cap, before and after the center-spotting... Incidentally, the telescope arrived nigh on perfectly collimated. It also has a glued-in primary mirror, and is essentially the same kit as the Sky-Watcher Heritage 100P. In the case of your spherical mirror, I'm thinking that it might be necessary to add some thicknesses of paper on the underside of the pattern near the outside edges so that the reinforcement will just hover in the air above the mark before you press it down. I may be wrong about that, however, as I do not have that particular telescope.
  15. There could be pieces of metal shards lodged inside, and from the factory. It wouldn't be the first time. When cleaning out the old grease, I've found that charcoal-lighter fluid, the kind for grilling outdoors, works wonderfully in removing all traces of the old grease, with rags and an old toothbrush. I did the same to my EQ-3. It's much smoother now. When re-greasing, only small amounts of the new grease are needed, particularly with the Super Lube.
  16. If you're up to it, and good at tinkering, disassemble the mount-head, both axes one at a time, and clean out the old factory grease and re-lube with a quality grease. I use this for all of my astronomical equipment... https://www.amazon.co.uk/d/Lubricants/Super-Lube-Synthetic-Grease-Syncolon-Multi-Purpose/B000XBH9HI It's PTFE, or Teflon, based. There are other greases that can be used as well, and instructions online to help in disassembling.
  17. A fellow amateur, who lives in Denmark, saw a few of the Bresser refractors first-hand, and was of the opinion that they, the refractors, were a notch up in overall build-quality compared to those of Synta(Sky-Watcher, etc); for what it's worth. The primary mirror will be a parabola, of course.
  18. If you have recourse to recovering your funds, if it doesn't prove to be as advertised, I'd say go for it, and before someone else goes for it.
  19. Aside from the wrap, it nonetheless looks to be new, and is indeed a 150mm f/5 Newtonian; perfect. The image within the link is of the longer f/8 variant, which are usually mounted on a Dobson alt-azimuth or on a large equatorial(EQ-6).
  20. The 45° Amici diagonal is really only suitable for daytime/terrestrial use; for observing birds and what-not. Consider a 90° star-diagonal for astronomical use at night... 1.25"... http://www.rothervalleyoptics.co.uk/antares-90-star-diagonal-125.html 2"... http://www.rothervalleyoptics.co.uk/altair-astro-2-mirror-star-diagonal.html ...for examples.
  21. The 100ED would indeed be worth the striving towards, as the Japanese Ohara ED-glass element is FPL-53, and the best optical-grade glass in the world at present, second only to fluorite, with the other element being of German Schott crown.
  22. I read somewhere, recently, someone saying not to let Sky-Watcher know just how wonderful the 100ED really is.
  23. If you didn't have a fast 102mm refractor, I'd say go with the 102mm ED. What about a 150mm Maksutov; that for lunar and planetary, and the fast refractor for wide-field deep-sky?
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