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Piero

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Everything posted by Piero

  1. As far as I can see, your secondary mirror is titled and too low with respect to the focuser axis. As not all the primary mirror is reflected on the secondary mirror, there is also some aperture loss. Coming back to your questions, yes, it is absolutely possible to see the three clips of the primary mirror (and you should see them!). Your collimation issue can be solved. Could you take a photo of your secondary mirror holder from the front of the tube, please? Secondly, which tools do you use to collimate your telescope?
  2. Thanks guys for your comments. Yes, I spent a lot of time trying to figure out the source of the problems and this effort has been quite frustrating at some point. Whilst I think that every telescope is not perfect and can require some adjustment, it should still be functional. Unfortunately, this was not the case for this telescope. There are other things that could have been implemented in a different way, more in line with most of the other designs. For instance, the truss pole attachments, the plate holding both the focuser and the finder, the wood plane making the primary mirror cel
  3. A while ago, I decided to spend some time in re-design the mirror cell supports of this telescope, in order to fix the issues of astigmatism and spherical aberration once for all. I have tested this new design on a few sessions in the field, with very positive results. The telescope delivered very crisp and details views of the moon up to 300x (limit caused by the seeing, really). Stars were puntiform and uniform. A lot of small faint stars were visible. Off-axis views have improved massively too. In addition, the telescope behaviour has become consistent between sessions and within the same s
  4. You don't see the 3 clips because your focuser axis is not aligned properly. You collimate this adjusting the 3 screws behind the secondary mirror holder. If you don't have done it already, I would suggest to replace those screws with Bob's knobs (FLO sells them), to make the focuser axial collimation much easier. Once the 3 clips are visible, you can proceed with the primary mirror axial collimation.
  5. I read rumours about this a while ago on CN. Personally, I keep my 30mm APM UFF.
  6. The 32mm TV plossl is a nice and quite comfortable eyepiece. The only reason why I sold mine is because I have the 24mm Pan, which I find more engaging.
  7. Great stuff, Gerry! Hope you find the push fix adapter as useful as I do!
  8. In Italian, we call it sen or sin.
  9. And here giant VIPs for T2 or 1.25" eyepieces if needed:
  10. As I use my VIP only in 2" / T2 mode, I don't need the 2"-to-1.25" reducer. That reducer is a well made one, but it is a reducer in the end. There is a downside if the top T2 is used: the brass ring locking a 1.25" eyepiece is in the light path and it can cause light scatter on bright objects (e.g. the moon). The reducer is also rather heavy. So, here the plan: replace the 2"-to-1.25" Baader reducer with 2" / T2 Baader nosepiece (part no. # 2408150). This weighs slightly less than half the reducer, does not have the issue of the brass ring, and allow me to use the reducer as such (e.g. w
  11. Really fascinating thread! Good luck with this project and looking forward to hearing more.
  12. I wanted to buy this a long time ago.. now it's here
  13. If the secondary mirror is slightly oversized, its alignment is far less critical than what one would imagine, for visual work. For imaging, it's more important. Try to get the three rings as concentric as possible: edge of the sight tube, secondary mirror, and primary mirror.
  14. Yes, go for a 8 or 9x50. Much better and it is still light.
  15. Thanks for sharing this, Gerry. I agree with you about the fact that truss dobsonians can be quite demanding. In my case, I saw a noticeable improvement since the telescope lives in the shed. This is a well built one. Temperature inside is about 1 C higher than ambient. In the summer, the telescope dislikes the light shroud, whereas it loves the fan. The effect is rather obvious. As we are approaching the colder seasons, body heat does affect the views, so I started using the light shroud. This works, but does not like the fan on! Therefore nowadays the fan is on when I mount the tel
  16. In terms of loss in detail off-axis (from about 50 deg AFOV). To my eye it is rather soft when compared to the crisp axial view.
  17. I haven't decided yet. Before this, I want to reduce the currents in the tube and understand the interplay between fan and light shroud. I am not a great fan of 100 Deg eyepieces (which is a good thing when coma concerns), but I can still see coma with my other wide angle EPs. At f5.9 this is not too much on star fields, but it is a bit annoying when observing the Moon e.g. with the docter. I am pretty sure planets are also affected although I tend not to observe them near the edge. Your new paracorr2 will also give you rewarding views with your 15", given the small native di
  18. Sounds great, Gerry! Any chance to test the Docter and Zeiss Zoom too? I've not read a comment on how those two eyepieces perform with the paracorr2.
  19. I found the amateur astronomer's handbook by Sidgwick so interesting, that I decided to get its complementary book too. £3 delivered and in very good conditions.
  20. In order to improve collimation and remove the block screws, I have been considering the replacement of the default springs at the back of my Sky-Watcher 8" dobson. As the telescope is in Italy, this work will be done at Christmas. Has someone done this before? If so, which springs do you advice? Thanks, Piero
  21. Found a copy of this for just £0.70!
  22. Just thought about sharing these two articles I read this morning. The Clouds of Venus Puzzle Scientists: https://www.skyandtelescope.com/astronomy-news/venus-clouds-puzzle-scientists/ Video: Black Hole Warps Light: https://www.skyandtelescope.com/astronomy-blogs/black-hole-files/video-black-hole-warps-light/
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