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Pixies

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Everything posted by Pixies

  1. It'll be like Lord of the Flies!
  2. Is the focuser draw-tube protruding that far into the tube when you are focused on a star? if it is, I'd say that your blurriness is a contrast issue caused by the size and shape of the secondary plus the draw-tube, too. Can you aim it at the sky (away form the sun) and, with it focused, take out the eyepiece and take a quick picture down the focuser?
  3. Probably dust sticking to the oil from your lashes. I'm interested in the answer too. I probably only clean them a couple of times a year! I do occasionally check them against some white paper and they never get that dirty. I don't wear mascara, though!
  4. My kids are 14 and 16. Is the a mobile signal?
  5. I've wondered about that location for a family break before. Some parts are Bortle 1, aren't they?
  6. Pixies

    Tak Erfle 28 mm

    FLO have one is stock. Apologies if you are wanting a pre-owned one for less £££
  7. As John said, with the zoom, the FOV decreases towards the 24mm end. If you are star-hopping through the eyepiece, you need a low powered EP. I have the Baader zoom, plus the matching barlow. You can find them second-hand occasionally (as I did). I have a few low-powered EPs but the one I use the most is the Vixen NPL 30mm - nice simple and light. You can get wider views - down to a 32mm plossl - which is the widest field for a 1.25" EP. You also have the option of 2" EPs. The zoom is useful for working out what fixed IP you might want to use, but half the time I just stick with it. It's also great for planetary observing, when you end up flitting between different (higher) powers, to get the best view in variable seeing conditions.
  8. Well, not mine, actually - but they appear to belong to these friends of Mr Bowie: Vixen Custom 90M, I think!
  9. My first telescope was very similar to this: I spent more time spying on the neighbours (innocently I might add) than astronomical observing with it!
  10. re-issued in '74. I remember forcing my parents to drink moe tea, so I could get more cards and trading them at school. Not something I could have done aged 4!
  11. For me it was this in 1974 (I was 7) And the total lunar eclipse in 1975 - allowed to stay up late to watch it reach totality.
  12. @Stu1smartcookie - how tight are your secondary mirror vanes? I thought I had some mirror slip with my 8" dob, but it turned out it was the secondary assembly flexing between horizontal and vertical positions. If you have a laser, see whether its position in the doughnut moves as you change altitude.
  13. I have been camping near Weybourne a few times, usually (as with most UK holidays for us) it was cloudy! I remember one clear night, though, trying to guide people to see Andromeda through hand-held binos. The campsite fires/lights broke dark adaption unfortunately. Thanks for the inspiring report @John - I need to head back to the local SQM 21.7 site soon. Hopefully next new moon.
  14. Does anyone know the RAL code for Vixen green? Not that I'm decorating the 'study', or anything like that! I might take the Super Polaris polar scope cover down to B&Q for a colour-match!
  15. Not meant to be a silly question, but how dark-adapted were your eyes?
  16. Do you have a Cheshire / sight-tube? You need something like that to confirm your secondary mirror is aligned under the focuser and not twisted. A laser won't help with that. Or alternatively a concentre?
  17. It's hard to say for sure. It's probably fine for visual observations - you can check with a star test. If you want to be precise though, you would do better with a bright background behind the secondary, so that we can see the circles of the focuser and secondary mirror, so that we can check they are concentric.
  18. Just for comparison. the FOV for this combo is similar to using a 6mm Plossl (x250) Not surprised you are having trouble landing on it, even with a GoTo. Even without a flip mirror, with the AZGti mount tracking the target, can you centre on it using a wide-field EP first, then switch to the cam?
  19. Blogs - never looked at these before - but saw an entry along the 'side' of the home page. Nice reports. The dumbbell REALLY benefits from a UHC or Oiii filter though.
  20. OK. I have been thinking a little more. Forgetting about the correct offset/size of the secondary for now. 1) make sure the focuser is set up correctly. I.E., its central axis intercepts and is perpendicular to the central axis of the scope. 2) the centre of the primary is marked. Now - it doesn't matter about the offset or size of the secondary, as this only affects field illumination. Worry about that later! Just adjust the secondary angle so that the primary centre spot is directly central to the focuser view. You will have to make sure the secondary is facing the focuser by rotating it and looking for the widest angle as seen through the focuser. As long as 1 and 2 above are correct, you now know for certain that the secondary is at 45degrees and the central axis of the focuser is aligned to the tube axis (via the centre spot). All you now need to do is the usual primary collimation so that the primary is aligned back up the same axis - either laser or Cheshire/collimation cap. When the primary centre spot is dead-centre to the focuser and the primary reflects the collimation device back to the same central point - it's all aligned and straight. Just assuming 1 and 2 above. Then you can worry about secondary size and offset. But this is all to do with field illumination. Any comments? I think that's correct.
  21. I've seen articles on how to calculate the correct size and offset for a secondary mirror. Scope builders will be very familiar with this, I'm sure. However, I also recall seeing an article about offset that shows an older method where the secondary is offset differently with the primary slightly tilted. Perhaps that's more applicable to a spherical primary mirror, where off-axis objects are less affected by coma, rather than a parabolic one. Anyway - I'm not an expert and I'm sure a few will be along shortly. But I reckon some scope-builders will be a good source of advice. As for your cunning plan to align the primary first, then (I assume) align the secondary from that... The trick will be making sure you can accurately align the scope with the laser. I would have thought it easier to make sure your focuser is straight/perpendicular to the tube, then you can use a correctly configured/offset secondary. The issue will be finding the correct secondary configuration, but that must surely just be a case of finding the correct advice/experience?
  22. Hi Mark, In modern scopes, the shape and offset of the secondary are such that when they present a perfect circle concentrically under the correctly aligned and perpendicular focuser when collimated correctly. As for off-axis targets. That's a fact of Newtonians - the more off-axis it is, the more coma you see. That's why when you are collimating a scope with a star-test, the star has to be dead-centre. As you move the star away from the central axis, you'll see the diffraction rings start to 'bunch-up' to one side as the coma increases. Our scopes are usually slow enough that coma doesn't really bother us visually if viewing objects off-axis in a well collimated scope. Well - that's how I understand it to be.
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