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Astro-Geek

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About Astro-Geek

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    Norfolk, UK
  1. A "miniature" observatory is on my future plans too, just like Billy's (very neat too). When looking for ideas, I always find a Google image search gives me hours of inspiration, (and it's a relief to find so many people with the same idea !) https://www.google.com/search?q=observatory+shed&client=firefox-b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjEkbX5oIPfAhUPWsAKHbf-BbwQ_AUIDigB&biw=1535&bih=768
  2. Astro-Geek

    Tube rings

    As Alan said, yes, on that list, 140 would be the nearest. However, when I googled "tube rings", I came across this page https://www.365astronomy.com/SkyWatcher-120mm-Refractor-Tube-Mounting-Rings-WHITE.html ...which lists a set with a 130 inside diameter, but then frustratingly doesn't individually show them.. Maybe worth ringing a few suppliers or further google searching, just in case they are available, as they would presumably fit nicely without any extra packing.
  3. Astro-Geek

    Tube rings

    As Waldemar calculated, 130mm is the exact diameter, but be careful of rings advertised as "130 rings" because they would probably be approx 159mm internal diameter. That's becuase the usual naming convention is for the diameter of the mirror or object lens of the telescope that they fit, which is usually smaller than the OTA tube diameter. For example, I use Celestron "130" rings for my deforked Meade ETX 125, which has an outside diameter of 147mm, and the 130 rings are about 159mm internal diameter (the nearest I could get).
  4. I spent a lot of time trying to work out which scope would be the best compromise for me too. There's such a mouth watering choice now, in every type. Do we have to accept compromise and stay loyal to one type of scope though ? Thank God for standardized dovetail mounts and eyepiece diameters, most can be used interchangeably on every OTA that we possess. OTAs may be the biggest and most prominent items we use, but we probably eventually spend far more on tripods, eq mounts, eyepieces, imaging kit etc. which stay with us even when we upgrade the OTA. Judging by the content on here, I certainly wouldn't consider myself an expert or even of "average" competence on this forum (yet !), but I use a 5" Mak, an 8" Newton, and a 5" Refractor, and each is great at something. Now that I've got used to each on its own forte, I'd rather not rationalize.
  5. Thanks again, all replies have been duly noted and I'll add them to my searches.
  6. I must admit, despite John & Moonshine already suggesting a Barlow, I was still resisting that route because I had a bias towards "prime" eyepieces (if I can use that term !). It does indeed make sense however, to effectively halve the cost of a nice new wide field eyepiece, getting two for the price of one..... My 2x Barlow is a Celestron Ultima SV model 9356, which I believe is of reasonable quality ? (would it do an ES justice ?)
  7. Thanks for the prompt and helpful replies. I do have a Barlow ( A celestron x2), and it works quite well, but I was wondering if dedicated wideFOV high mag eyepieces would give much better results, particularly with my 1000mm FL scopes. I'll have a look at the ES's and the Nirvanas.
  8. I use a set of Meade 4000 plossi eyepieces with my scopes ( a 1900mm Mak, a 200mm Newton, and a 120mm refractor). They're all 1.25", and they range from 40mm down to 6.4mm. I'm quite satisfied with them except the 6.4 , with its very narrow FOV and very limited exit pupil/eye relief. I know there's got to be a trade off with increased magnification, but I was wondering about the wide variety of much more "bulky" looking eyepieces in the 4 to 6mm range that advertise wide FOVs and long eye relief. (still with the 1.25" mounting). Are the presumably much more complex glass elements able to give significantly better high magnification views than my simple 6.4 Plossi ? (it appears to have just one tiny element). ....and if so, are they just the really expensive ones, or do they come down the mid price range as well ?
  9. I think Olli might mean the finder locking screw rather than the spring loaded centering screw. I've had a couple of those snapped off in the finder bracket on items I received through the post. They're very fragile because the knurled knob is so big and the brass thread is so thin. (Note to self,I'll always wind them right in before posting !) Luckily, because of my other interest in RC aircraft, I already had plenty of short plastic head knurled bolts which fit the thread (M3, if I remember correctly, but will check). I find them better than the originals because the knurled part is slight larger diameter (10mm), which gives a better grip and is lighter and less prone to break. Best of all, a packet of 50 was about £4 from RS, with postage !
  10. I'm still undecided about my ETX125. Whether to sell it as is, complete with a fully working mount, and buy a Skymax 127,150,180, or a Celstron C6,C8..... ...or..... To keep it, defork it (again), mount it in rings and dovetail and use it with my CG5 and AZ4 heads. I say "again" because I've already tried it like that and was pleased with the versatility and convenience. ...but I then persevered with it's mechanical mount problems and replaced the damaged nylon gears and got it working 100% with its original forks. When working properly, the Meade goto mount is very good, especially the PE with auto levelling etc., but the whole thing is a much heavier lump to set up with it's permanently attached fork mount compared to how light and versatile it was with rings and a dovetail. The dovetail method also allows much easier and more efficient balancing compared to the add-on weights bar with the fork. It even works well with a skywatcher AZ goto mount, being within its 5kg payload rating, making it a very lightweight portable outfit for visuals only. I've scoured the Internet looking for user's comparisons between the ETX125 and skymax and celestron Maks and SCTs and it generally gets a really good rating for its optics, hence me wondering whether I should just keep the re-converted ETX and sell the empty mount, or sell it complete and buy a Skymax Mak/Celestron SCT. ETX's seem to have a very poor resale value because of their bad reputation for mount reliability. Would I find the optics of a Skymax 127/150 or a Celestron C6 significantly better enough to justify switching from the ETX ? (just the optics). ( I do also have a 200PDS and a Startravel 120, so my little Mak is just for planets and the moon).
  11. I wish this thread had been around when I bought my first Dob a few months ago... The replies highlight moveability, which I underestimated. For anyone else contemplating 8, 10 or 12, age and strength (and back health !) are vital factors. I initially went for a 10" GSO with a solid tube (because the flex is actually heavier, and the base is identical), because I had no need to transport by car. I'm lucky enough to live in a very rural area 10 miles from the nearest city and with no street lights. I misjudged the movement in and out of the house though. My conservatory accesses the patio via a single width door and three steps, and it's quite a struggle for me (67 years old), to lift it in and out, even in the two main parts. If it was like my previous house, with a wide patio door and level surface, it would have been a breeze, especially as I tried mounting it on a triangular furniture dolly with large ball bearing wheels. I therefore subsequently bought a 200pds and EQ mount, which is much easier to get through the door and setup, and a 200 dob would be even easier. If anyone reading this is old and (slightly !) decrepit like me, try to handle a 10" before you buy, rather than judging by photos and dimensions. The weight is not the problem, it's the bulk and awkwardness, especially the dismounted OTA, which is like struggling with slippery slim Dalek, with a fragile glass bum !!
  12. Thanks for that link BD, I wondered if there were any alternatives out there. They look much more usable than my Binomate, but way above my budget unfortunately.
  13. I acquired a "Binomate" binoviewer with a second hand Meade ETX125 Mak. It works really well with that scope which has a very wide focus range, so it can achieve prime focus without a Barlow. When I subsequently bought a 200p Newtonian for deep sky and astrophotography, I specifically went for the 200PDS version with the greater in-focus, in the hope that would allow me to use the Binoviewer at prime focus without a Barlow, but unfortunately it's not quite enough, so it still needs a Barlow. The problem is that greatly increases the magnification and reduces the fov because of the significant extra distance between the barlow and the two eyepieces. The Binomate adds to the problem by having a non-standard thread nosepiece, so a Barlow nosepiece can't be screwed straight onto it. When I use the Binomate with the ETX, the views of the moon are superb, and the greatly increased maginfication is then a bonus, with the ample light available. I've replied to Olli's thread because my particular Binoviewer is quite a dissapointment with the 200P (even the PDS), and unless other makes can solve the prime focus/excess maginification problem, I would suggest trying one first with that scope before buying, if possible. http://www.astronomyreviews.com/allscopes/dabinomate.htm It makes we wish I'd bought a flex-tube 200 instead, which has the unique advantage of being able to reduce the primary to secondary distance by any amount by not extending the tube fully.
  14. I don't think it should be taken as any indication of the 200p Dobsonian being inferior or having some hidden shortcoming. As has been mentioned already on here, telescopes have become much more popular as "whim" buying items than ever before. Anyone who owned an astronomical telescope 50 years ago (or yearned for a good one !), can appreciate how cheap really good quality scopes are nowadays by comparison. The best that most dedicated amateur astronomers could afford then were 6" Newtonians, and the richer ones could stretch to an 8". If memory serves me correct, even Patrick Moore only had a 12" Newtonian in his garden shed observatory, (and that didn't have a dome, it was just a wooden shed that slid open in two halves on rails). "Goto" wasn't even a miilionaire's toy, because home computers hadn't been invented. So many classified adverts for scopes contain phrases like "only used once", "unwanted present", or even "still in original boxes". I'd say that the majority of new telescopes are bought by people who have never read an Astronomy book or can identify constellations. Their expectations are (undertsandably) raised too high by today's plethora of high quality marketing images of Saturn and Jupiter, and are dissapointed at only just being able to see the rings and the red spot through their new purchase. One of my scopes is a skywatcher 200, and it gets the most use, being a perfect compromise between light gathering, magnification, and portability (for me).
  15. Astro-Geek

    Barlow for Binoviewer

    Thanks for the prompt replies. No, unfortunately the nosepiece of the binoviewer isn't threaded for filters. The first photo shows the nosepiece's non-standard stepped down thread where it connects to the binoviewer (the piece on the right), which prevents me from screwing the bottom half of a barlow straight on to it. (Next to it is the nose piece of my Barlow, which is threaded at its full external diameter, so can't screw directly to the binoviewer). The second photo shows that the nosepiece of the binoviewer is shorter than the sleeve of the barlow, so it can't even slide right in. The third photo shows my Ultima Barlow disassembled to show the length of the plastic female section. I'm wondering if I should buy another barlow and somehow adapt its lens to fit inside the nosepiece of my binoviewer to get it as close as possible ? I haven't managed to assess the magnification increase with my current somewhat extended combination, but it seems to be a lot more than x2, because I guess I can't get round the additional 100mm of light path within the binoviewer before it gets to the eyepieces ?
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