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Captain Magenta

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About Captain Magenta

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    Proto Star

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    www.slidingseat.net/stars/stars.html

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    Middlesex & SW Ireland
  1. My take is that it looks to me as though the secondary is a fair distance away from where it should be. One edge is deep in the light cone, and its rough-ish edge is causing all that extra diffraction. And the other side of it is way outside the light-cone, therefore causing no diffraction at the other side. Those two extra gaps are 120 degrees apart, which suggests that 2 of the 3 mirror clips are causing them. M
  2. Totally no apology required John, but thanks anyway. I couldn't ask more than to get the responses and input from such as you and Don - I've certainly learned a lot more than simply discovering that my Paracorr improves my view. M
  3. Yes I was about to demand an inquiry too
  4. Ah yes mine will be 300 not 305 so 5.3 of course. Given both Orion, obviously the same mirror I have had no problem with any of my other eyepieces but then I wouldn’t, seeing as the next up was my 18.2 so cutting out much of the coma’d area. As you say perhaps you are just not sensitive to it. I hope I haven’t caused you to “once you look for it you can’t again miss it”.
  5. Yes I drive my AZ-EQ6 with it. It generally works very well, but the menu logic for it takes some learning, specifically the functions of some buttons. There's one particular sequence of button-presses during alignment that is intuitive obvious and logical, but WRONG and fatal (to the alignment). Once you make that mistake, you need to reset the scope position and start again. I do it almost every time. But once you've got through that, it's very good. You can use everything you observe as an extra alignment point, so it gets more and more accurate during the session. The "Tour" feature, the catalogue-selection, the sheer number of catalogues, and the notes on each object, are all brilliant. I have ordered an encoder unit for my AYOii mount which is due soon, so I'll be able to use the Nexus DSC in "push-to" mode as well, as originally designed. And in due course I intend to get a largeish Dob.
  6. Funnily enough the OO mirror I ordered during Lockdown has just been completed and is about to be delivered. It is 1590mm apparently and is intended to replace my SW 1500mm, turning my f/4.9 into a f/5.2 - the comparison will be interesting. Though I'll need to do a bit of tube-surgery to install it. In time I'm going to order a custom carbon tube for it.
  7. It did, I think. I thought initially it could simply replace the Baader 58mm extension on my Steeltrak focuser, but by doing that and sliding the Paracorr all the way in I couldn't reach focus. Luckily it has a very long nosepiece, so I just drew it out a bit and achieved it. Looking closely at one of my pictures, it does seem like about 10mm. I'll measure and compare properly in due course.
  8. I think the suggestion of a disappointed child's letter to the Council or someone, suitably publicized perhaps as an Open Letter, is not a bad idea. Also perhaps make sure to wear Hi-Viz vests when observing, they are incredibly distracting, even slightly annoying, to anyone just behind a bright light, so whenever you are all out there, the neighbours from the top windows will see these bizarre bright shapes and stripes moving around the otherwise inky darkness. M
  9. If you follow the thread What Did the Postman Bring? (esp @PeterW who requested a report), you may have noticed that I received a new Televue Paracorr Type 2 Coma Corrector yesterday, for use with my SW 300p f/4.9 newt. And what's more, the very day it arrived was forecast to be a perfectly clear night. Amongst my eyepiece collection I have a Televue Panoptic 35mm, which in theory was for use as a widefield eyepiece but whenever I have used it, such as to show the Pleiades to my neighbours last weekend, I've been disappointed by the severe coma-stars starting not far from centre-field. I've even been considering selling the Pan 35 for that reason, and have rarely used it. So I was especially curious to see how much of a difference the Paracorr would make. I set up last night as usual, without the Paracorr to begin with to have a direct front-of-mind point of reference, and after alignment I slewed straight to M45. Sure enough, the stars were spangly and the view was annoying. I put in the Paracorr, rotated the slider to setting "G" as per instructions for the Pan 35, inserted the eyepiece itself, and with a sense of trepidation I took a look. I no longer plan to sell the eyepiece. The view was suddenly wonderful. A field of extremely bright, pinpoint stars all the way to the edge, just as M45 should be. Sure some diffraction spikes on the very bright ones but I don't mind those. I went on a tour of open clusters, M37 with its central red bright star, M36, and a host of fainter but no less more-ish clusters in the vicinity, using my Nexus DSC and its brilliant "Tour" function set to "within-10-degrees". It's expensive but it has completely transformed wide-field viewing with my medium-sized newt. Cheers, Magnus
  10. ... further thoughts. Either a suitably large rubber band which means you don't need to unscrew the tube completely. Or some PTFE tape around the threads, which means you probably will. Or both. M
  11. The blue tube, as I understand it, screws onto the rear plate. The black rubber/plastic ring both seals it and acts as a sort of "spring-washer" to lock the thread. If the rubber ring has broken, the thread is freer to wobble around. See my detailed post here about disassembling my own Skymax 180, whose design is similar but has the middle tube bolted to the rear cell rather than threaded on. Your scope I believe will have a similar overall design, apart from the threading of the tube. The main collimation bolts, for example, hold the whole primary mirror in place and are its only connection to that rear cell. DO NOT undo those collimation bolts! I think you can safely unscrew the whole tube from the rear cell and lifit it off to expose the innards and primary, but be careful when balancing it on just the visual back! You'll need to find a replacement large O ring or similar way of preventing the thread wobble, maybe some thread-lock? My verdict: totally fixable. I hope that's been helpful! Cheers Magnus
  12. I’m seriously beginning to think my corrector is obviously rubbish. The very day I get it, there’s not a cloud to be seen and it’s due to stay that way all night...
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