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melsmore

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Everything posted by melsmore

  1. Upgraded my GPD2 with Skywatcher GOTO. Works well, but the housing cover doesn't fit very well. Thank goodness for American Tape. Here is first run for it - to see if I RT*M properly. I didn't want to risk my SD115D nor APM140, so the TS80APO it was.
  2. Good points. And I've yet to see the SCP.
  3. La Palma for some winter sun. New moon in Jan or Feb best.
  4. Not really night, but as close as it gets at 53⁰N at this time of year. First light for my new APM140, which I collected today from The Widescreen Centre. A low Venus and the Moon, briefly before they dropped below the treeline, then Polaris and Mizar. My GPD2 mount managed the weight (around 10kg) just fine for visual. Too soon to have a considered opinion, but very pleased with it so far.
  5. What @Merlin66 said and look at the Double Star Imaging group
  6. I like my Vixen SD115S a lot, but it is F7.7 (f890) and over £2K new. It's not particularly light at 6.5kg either. But it's a doublet and a darn fine one. P.S. no, it's not for sale
  7. Thanks for the encouragement @globular, @andrew s and @dweller25. Yes, I think the white patch at the bottom and left sides were cloud. I looked for a photo or competent sketch here and on ALPO for the same time to check with, but couldn't find one.
  8. First the disclaimer. This is my first attempt to sketch Mars, or indeed any planet. Also, it started to rain and I had to abandon it with some urgency (hence no orientation marker). I used a HB pencil and a blending stump. But I think I can see a couple of features that match Ade Ashford's app. The Wratten 21 filter improved the view enormously (although you may find that hard to believe looking at the picture) helping show the surface detail and improving the seeing. I tried it the day before in my 80mm refractor, but that just made the image too dim, but on the 115mm it was very good, so I recommend it to anyone with 115mm or larger. I tried sketching the moon (Plato) several years ago, but SWMBO pronounced it (I'll paraphrase her here) more Feline Anatomical than Selenographical. While this one may look more like a two year's old attempt at drawing a rabbit, at least no one can confuse it with the rear end of the cat. So regardless of the criticism I receive here, I'll give it another go tonight (weather permitting). 🧐
  9. Here is my newt, being diligently guarded by the head of security before he retired (to the sofa). It'll be 20 years old on 25/12/2020! Last seen by me in 2016 😭. We plan on going to the Moto Guzzi 100 year celebrations next September (subject to Covid-19 and/or the Grim Reaper), so may travel on down to rescue it after that.
  10. Farpoint Desiccant cap for my SD115S and #21 orange filter to try on Mars.
  11. Not far from me then, bit East of you on hols near Craster , fantastic skies here too... (Not tonight though).
  12. There's a Test Report by Alan Dyer of it in September 2020 Sky and Telescope too. (Page 68).
  13. And why not? It's always a joy to look at that combination.
  14. New sleeping bag for SD115S. The dog seems to have retired from security duties, hence the alternative.
  15. Excellent first light. Well done.
  16. That's not an "unboxing", it's just a box. You're taunting us. ☹️
  17. Yes, from me too. A terrific advertisement for TS and iOptron!
  18. New (to me) Vixen SD115S set up for first light. Birthday pressey from SWMBO.
  19. Very sorry, I just checked the current models of C8 and C925 on FLO's website and it is certainly no longer the case concerning the secondary mirror sizes. C925: Secondary Mirror Obstruction: 3.35 in (85.09 mm)Secondary Mirror Obstruction by Area: 13.1 %Secondary Mirror Obstruction by Diameter: 36.2 %Optical Tube Length: 22 in (558.8 mm)Optical Tube Weight: 20 lb (9.07 kg) C8: Secondary Mirror Obstruction : 2.5 in (63.5 mm)Secondary Mirror Obstruction by Area : 9.8 %Secondary Mirror Obstruction by Diameter : 31.3 %Optical Tube Length : 17 in (431.8 mm)Optical Tube Weight : 12.5 lb (5.67 kg) Sorry, next time I'll check before I post.
  20. My MAK127 is kept indoors (no cool room) and It takes 30 minutes or so to cool down - almost exactly what @vlaiv extrapolated from his! I plonk it outside first and by the time I've polar aligned my mount and faffed around it's just about good to go. Wooden sheds (in direct sunlight) can soak up a lot of heat and cool down slower than a MAK 🙂 The only (very minor for double star observing) drawback I have concerning my MAK127 is that I can't use 2" eyepieces with it . Also, mine came with a RDF, and as I don't have GOTO, I'd have preferred a finder scope. @Stu recommended the C925. I've never used one, but I have had this SCT recommended to me for this by others too. Apparently, it is good because theirs have the same secondary mirror as in my C8 giving a much smaller % obstruction - more MAK like in fact . When you say "do double stars" do you mean "looking at them and seeing if you can split them", or do you mean "measuring their position angle and separation too"? If it is the latter, then there are other considerations and I would recommend you read Argyle's book before deciding exactly what you want. I should say that I have the first not second edition, but I expect the second to be better.
  21. Would that include "During the favourable opposition [of Mars] of 1892, W. H. Pickering observed numerous small circular black spots occurring at every intersection or starting-point of the "canals"? 😁
  22. Thanks, very interesting link - especially the conclusion in section 5.1.3. I've always thought that the average cell size here is fine for telescopes up to around 12" ( can't remember where I read that) and I can't say I've ever changed to my Mak127 or TS80APO because of seeing. I've often had to wait one or two hours for my C8 to stabilise thermally though, and when I had an 8" Newton, I often had to swap to one of the others due to meteorological wind. CONCLUSION What all this implies is that it is possible for a significantly smaller aperture to outperform the larger one, but it requires them to be, and remain at a specific seeing error level, generally involving compromised seeing conditions. It is only possible when D/r0 in the larger aperture is ~4, or larger, in which case a smaller aperture with D/r0~2 will have - all else equal - better resolution and contrast transfer. In other words, smaller aperture could perform better while the seeing error is large enough, but if it lessens sufficiently due to seeing fluctuations, larger aperture would rebound and perform better. Typically, seeing fluctuations are wide enough for that to happen.
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