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    SGL 2017 SP


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About Piero

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    Sub Dwarf
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    Amateur astronomy, biological signalling networks, bioinformatics, software engineering, mathematics, languages.
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    Cambridge, UK

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  1. Aside from limiting dew formation, how much effective are they at reducing stray lights? I'm considering one for my 8" dob. Any experience? Thanks, Piero
  2. FLO sell them, but it seems they are out of stock at the moment: You can also get the Glatters tools from (Denmark). I bought a few items from them and their service has always been excellent. Jan is a very nice bloke.
  3. Great tools, great collimation! Love mine! Congratulations for the purchase! To add more information, the Glatter laser can be red (650nm), red (635nm), and green. for daytime/twilight collimation, one might want to consider the 635nm model for nighttime collimation, the 650nm is more adequate in my opinion as the red light is less brighter than the 635nm. Because of the brightness for the 635nm model, Howie invented a `brightness controller`. One should make sure that the 635nm laser can be upgraded with this first. This is called `Howie Glatter Laser Battery Cap / Switch Upgrade with Dimmer Control` and currently sold by FLO: The Glatter's tools make collimation a pleasure in my opinion!
  4. As far as I understand the most critical between the two is the 501nm, but for visual the 496nm is also quite relevant. There is a post by Don Pensack on CN where he describes the difference between the Lumicon OIII and the Baader OIII (which only passes 10nm cutting half 496nm signal) when observing the "Witch's broom" feature (see Gerry's post) in the Veil nebula: There is also a third OIII lane which is not critical and for this reason is discarded. Personally, I am more than happy with an OIII filter with specs: +90% transmission; both 501nm and 496nm; ~12nm `rectangular-shaped` transmission width Basically the old Lumicon OIII..
  5. If they really took that thread down, it is rather unfair.. In my opinion, although there were some posts which were too aggressive against Lumicon, most of them were really about the fact that keeping the same product name, while changing the specs, was kind of deceiving. Eventually, this was the reason of that (and this) thread. They could have just cleaned up the most aggressive posts rather than taking down a thread which is highly relevant for the astro community, I feel..
  6. A bit of information: Optical design for the Lunt 20mm HDC (as provided by HDC20mm.pdf Here is a size comparison between the Lunt 20mm HDC vs ES 30mm 82: Weight comparisons: - Lunt 20mm HDC: 677.6g (source - Ethos 21mm: 1020.6g (source - ES 30mm 82: 1032g (source - Docter 12.5mm UWA: 525g (source - Zeiss zoom 25.1mm-6.7mm: 490.0 g (source And here a pic showing how it fits on my 8" dob:
  7. Hi Mark, I bought it from APM-Telescope for £248 inc shipping and currency exchange. Very good service. I am not aware of any supplier in the UK.
  8. I bought the Lunt HDC 20mm because it received very positive comments AND I consider the current cost of the Ethos 21mm outrageous.. As far as I know the new HDC version is nitrogen filled and the eye cup can be removed. The eyepiece seems better than the ES 30mm that I have. In my F6 Dobson the field is clean until the edge. I could spot a bit of coma in the last 10% but that is due to the Newton. Using the NPB on nebulae I preferred the Lunt to the ES 30. Essentially the views seemed a bit cleaner and the contrast seemed a bit higher. The eyepiece is very comfortable and light. Its weight around 650g. Maybe it is my face, but I could see the whole field of view quite easily without spectacles, which I don't use for observing anyway. As I never looked through an Ethos 21mm and my Dobson is not too demanding with eyepieces, my comment is a bit limited. I really look forward to reading about how it compares against the ethos in fast dobsons. Even if it doesn't work well, it is still a valid alternative for medium slow telescopes, currently at a bit less than 1/3 the price of an ethos. That's a bargain to me..
  9. All these filters work better under dark skies. Under moderately light polluted skies, an OIII filter is still helpful, but the view under dark skies is just much better. Some features will be visible with direct vision, others with averted vision. Patience at the eyepiece and dark adaptation are needed, and they will pay you back nicely. p.s. observing under a decent dark sky surrounded by nature is one of the best experiences I have ever had. Just natural noises around and a crazy amount of stars above. Wonderful!
  10. Com'on Gerry ( @jetstream )! we are curious! (My choices: for extended nebulae the minimum I use is 2mm. For planetary nebulae I successfully went down to 0.8mm.) Edit: Oops.. I read the question wrongly.. I thought Neil asked what Gerry advises as minimum exit pupil when nebula filters are used. Apologise!
  11. Yes, a log can really help. One can understand sky conditions, target details, equipment, etc while recording each session. I used to write down my sessions and I believe I learnt a lot from them. The only reason why I stopped is that the reports were getting repetitive. Basically I finished off the list of targets I can see with my 60mm under my local skies. Here are examples:
  12. Congratulations for your purchase! I had many thoughts about the Tak LE-HI 3.6mm. Here is a thread I started on CN as there are more `LE owners` over there: . Not much information to make me press the button.. As you said the cost of a new one is very high, and the one you got was actually the first one I have ever seen in the s/h market (at a much more reasonable price too!). I will read your findings and opinion about this LE-HI 3.6mm with great interest for sure! The coming years seem promising as far as these short focal lengths concern. I am looking forward to hearing about new Vixen HR focal lengths (hopefully, finger crossed!) and the new Tak TOE which will be available soon-ish, apparently at these focal lengths: 2.5mm, 3.3mm, and 4mm (all 52deg afov, 10mm e.r., 6 elements 4 groups design). A few people on CN compared the Vixen HR 2.4mm with the Pentax XO 2.5mm. The former seemed to be right there with the latter. If it is true that Vixen bought the patent of the Pentax XO, this should not be too surprising. I really wonder how the Tak LE-HI compares with the Tak TOE or Vixen HR..
  13. What a wonderful description Gerry! While reading your thread, the words that Rob (Qualia) wrote on his SGL profile came into my mind: "The lesson of humility is so often brought home to us in astronomy..."
  14. Well said! It is still a very beautiful target and we are lucky that it is not too far away. Think about if a planet like Saturn were located on Pluto's orbit!
  15. You are welcome! Forums like SGL are made for sharing information and our passion for this hobby!