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About markse68

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    Proto Star

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  1. Anyone else mad enough to stay up for GRS transit and a bit later Io shadow then Io transit this Sunday morning? Forecast looks good
  2. I caught the ISS pass earlier this evening with the telementor. Then my boss walked out and of course wanted a look (it’s currently my work scope and I’m always there late- don’t ask lol) But with the reversed image and him not being used to it of course he struggled to keep it in view. But it’s got a sort of rifle sight on it so I stood behind the scope (lucky I had the diagonal in) and kept it on target so he got a good long look- he seemed quite happy
  3. Nice project! The base plate looks awful thin n flexible for 3D print?
  4. Sorry to hear that Dave- hope you’re on the mend
  5. Do you lose any fov using it like that Dave? I did purchase an old slr amgke Dundee for just this purpose but abandoned idea as it had a much smaller afov but maybe the one you got is better
  6. I love your attitude Chris I really do- it’s totally in the spirit of John Dobson too I’m too far into this now-I just want a “traditional” design that’s better than what I have inherited and using now and to get it as close to right as possible first time
  7. There's some discussion in several threads but here's one which links to a 1949 piece by Andre Couder https://www.cloudynights.com/topic/545953-are-curved-spider-vanes-better-and-if-so-why-are-they-not-standard-equipment/page-3 https://translate.google.co.uk/translate?sl=fr&tl=en&u=http%3A%2F%2Fwww.astrosurf.com%2Faltaz%2Feffetthermique_e.htm
  8. But I don't have your years of experience though Are you saying the calculator will not give accurate results? If it does then surely it's a pretty useful tool for someone with less experience who doesn't want to build multiple dob bases trying to get the right feel? I like your method for reducing the AZ bearing friction but in my case (8" dob) the problem I think I'm going to have using that calculator is having too little friction! I could use nylon instead of PTFE but then the friction goes up too much. Based on the results of the calculator I'm thinking I might have to increase the ALT bearing support angle to try to increase the ALT friction to match the AZ friction but then I'm going to use Tufnol for my ALT bearing rings and the COF is a bit of an unknown... AND they're both coming out a bit low and I don't want to increase my AZ bearing diameter too much more Mark ps Mel sent me a link to improved calculator it has choice of units my calculated values seem rather low Edit it I forgot the link http://bbastrodesigns.com/NewtDesigner.html#movementFriction
  9. There's a thread over on CN that advocates leaving spider vanes polished metal- the theory being that black body radiation can actually lead the blades to cool to below ambient temp causing a thermal gradient and increasing diffraction! Does that sound likely to you Andrew?
  10. I have to confess to only flitting through your build thread- it’s quite long I’ll sit down and go through it more thoroughly I promise What I saw looked really great though I never would have believed that paint would stand up to that much use but I guess it goes to show how low friction ptfe really is! (And how tough hammerite is!)
  11. Interesting- has it lasted? Wouldn’t have thought it’d be as durable as Formica but I guess when it’s fully cured it’s pretty tough stuff
  12. Good to see another 4.8mm Nagler in this thread I found it does have a couple of niggles- I guess the reason it’s not very popular now is the short eye relief but I find it no worse than my 6mm ortho and I’m ok with it though it takes getting used to the eye lash squishing. I used mine trying to split Sirius earlier in the year and when I finally got the conditions I could indeed see the pup with it but prior to that it exhibited a slight ghost image of the very bright Sirius which had me fooled at first till I realised it was moving the opposite direction to the star ;). It’s been wonderful on the moon on nights of good seeing in my 8” f8 lately
  13. Lovely moon pics- it was quite beautiful wasn’t it! I watched it setting beautifully framed by some construction cranes and stupidly ran off to get my phone and holder- it had disappeared by the time I got back
  14. Hi Mike, how would you describe the view through a PM ep? As I understand it it’s like a plossl design with an extra correcting element thrown in. Plossl tend to get a bit soft at the edges and suffer pincushion distortion- is the PM simply a better corrected Plossl? Are the so called Super Plossl a similar design? Mark edit- did I look through one last night? Is the parks 10mm here a PM design? That would be quite funny! It was perfectly sharp to the field stop and showed as much detail on Jupiter as the BCO maybe a little warmer by comparison though. Then again the BCO has always struck me as being very cold- which is reality I don’t know...
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