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Piero

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Everything posted by Piero

  1. If you also want the description of the objects you observe, then I'd suggest to also get Burnham's celestial handbook in the second hand market.
  2. That's a stunning image! I was observing that area too a couple of days ago.
  3. Last week, when the moon was not out, I was star hopping the Plaskett's star in a field down to 14 mag. Not that I needed to go so deep, but I wanted to make sure I was identifying it. I found sky safari quite accurate, particularly after aligning it to the telescope axis. I have the Pro version, but the Plus version would probably be fine too. If one needs deeper DSO, she or he can always download extra data. The current database is already huge though, probably on par with sky commander. You are correct though, very low temperature can affect the performance of a tablet battery and poss
  4. I have the Lunt / APM HDC 20mm. The field is well controlled up to the edge with very minor astigmatism in the last ~5% of the fov. Honestly, you need to look for it. The lens rubber is particularly comfortable. The eyepiece is quite light (678g) when compared to the Ethos 21 or ES 20mm 100 deg. In general it is a fine eyepiece. Mine does not get much used simply because 1) I prefer eyepieces with a smaller AFOV (I kind of feel lost with 100 deg), and 2) as my telescopes are medium / slow I tend to jump from 30mm to 12.5mm. p.s. Mods might complain the fact that you asked about buying /
  5. Yes, encoders can be very valuable. Sky Safari can go quite close though, with the main difference that it lets you star hop.
  6. I have the S&T pocket star atlas too. For some reason though, I've never really got along with it whether indoor or outdoor. For sure I am a minority because all the comments I've read are very positive. The issues I have are: limited number of stars. Fair enough, it is a pocket star atlas, but on the other hand constellations are often in multiple pages. So it hits neither the detail, nor the broad view how pages are presented. I feel comfortable with pages following a decrease in RA. That's intuitive to me colours. Colours are fine with me indoor, not outdoor
  7. I've heard of, but never looked through them. How are they? Edit... just found this:
  8. The telescope has consistently been working very well for a while now. Stars don't show traces of astigmatism. Last night I had another nice session. The sky was rather steady and clear, with very low humidity. The telescope cooled with the fan on for about 2h and then collimated with my 2" Glatter laser (without tuBlug). Eyepieces: 30mm APM UFF (large targets), 12.5mm Docter (all targets), Zeiss zoom (all targets). 20mm Lunt was used for the galaxies, but didn't show anything more than the Docter. Lumicon OIII was used for the Eskimo PN. Main targets were: Monoceros: M50, NGC
  9. [A1] If the laser beam strikes outside the centre of the silhouette on the primary mirror, the focuser axis is misaligned. Assuming that this fact is ignored and one completes with the primary mirror alignment, the result would be that the primary mirror axis is "aligned" and the focuser axis is misaligned. To my understanding, this should show something like: In this figure, the focuser seems perfectly "squared" to the secondary mirror, the primary mirror is collimated, but the focuser axial alignment is still off. One could align the focuser axis first. This would make the seconda
  10. Having a budget limit is important, but understanding your interests is even more, I'd say. Let's simplify a bit.. Imaging. This has rather different requirements. Personally, I would keep this as separate. GoTo. Are you interested in GoTo mounts because you don't like star hopping much? A 10" (solid tube) dobson is a noticeable step up from your 6" and a very good all-around. Personally, I would get the "manual" version (=no GoTo) and learn how to move around the sky. I would then add a decent collimator, Sky & Telescope Pocket Sky Atlas, and 3 decent eyepieces
  11. As I've a couple of days off this and next week, I am revising my equipment a bit, which primarily means cleaning up and check that everything is okay. This morning, I took sometime to improve my Baader VIP barlow (now barely recognisable!). In particular, I added the standard ring 2"-to-T2 (which comes with the barlow) at the bottom of the 2" Baader nosepiece. This allows me to use 2" filters at the bottom of the nosepiece and just above this ring (see photos). Some tape was added so that the cap stays in place. This also facilitates the removal of the end component when the filte
  12. I had 1.25" Astronomik UHC and OIII filters but these were replaced by 2" DGM NPB and Lumicon OIII. No direct comparison was done between the NPB and the Astronomik UHC. Both are very fine. I prefer the NPB for the reasons stated by John.
  13. Yesterday I received a copy of interstellarum deep sky atlas (IDSA) so that I can visualise the location of the objects described by Burnham in his celestial handbook. I find this approach incredibly useful to learn more about the sky. This wasn't new to me, but when I was doing so, it was with my TV60 which is a bit limited in aperture. With the dobson, it's another story. Looking forward to start off making a good observing list for monoceros, one of my favourite constellation. Outdoor, I prefer a tablet with sky safari to a paper star atlas. The IDSA is a great and powerful tool, but
  14. Good luck with the restoration of this Dobson. Hopefully it will see some light soon!
  15. I also think that it is a good companion to Suiter's. Same for Texereau's how to make a telescope. Same for Burnham's.
  16. I bought a copy of IDSA, in order to map the objects described in Burnham's celestial handbook and create observing lists. The atlas for outdoor work is Sky Safari Pro instead.
  17. Star names - their lore and meaning by R.H. Allen is a classic one. It is mentioned quite a lot by Burnham in his Celestial Handbook, which is another classic. Both are highly recommended.
  18. Sidgwick's Amateur astronomer's book is excellent in my opinion. Very inspirational and rich of insights. A keeper.
  19. Thanks. Burnham cites that book quite often. That's how I became aware of it.
  20. By 'tipped' do you mean off-axis towards the primary mirror? 1. A primary mirror axial misalignment will cause coma on axis (coma due to misalignment). 2. A focuser axial misalignment will cause the stars to focus at different points across the focal plane. 3. A secondary mirror (severe) misalignment will cause unequal field illumination. It's rather obvious that only the first one degrades on-axis, therefore 2 and 3 reveal nothing on a star testing as this is conducted on-axis. Of the 3, the last one is the less critical for visual astronomy.
  21. If collimation of a, let's say, f5 Newtonian telescope without coma corrector is checked with a star test, the star must perfectly be on axis, otherwise the coma-dependent misalignment is also visible. This cannot be really distinguished by optical misalignment. So, again, to me at least star testing is not the right way to check collimation as it is too sensitive, unless the seeing is very good, the high power eyepiece is good, coma corrector is used, and the mount tracks automatically. Even so, this test doesn't tell you anything about secondary and focuser alignments.
  22. Not sure what some members above meant by star testing in this thread. Do they mean "checking" or "collimating" with a star test? In my opinion, I wouldn't suggest the latter, particularly with manual driven mounts. Regarding the former, the procedure can be rather complex as it is easy to get errors due to other factors which don't have anything to do with misalignment. Of course, if one knows how to star test, the feedback given by this tool is incredibly useful in order to understand what does not work properly in a telescope. Regarding the importance of collimation, well
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