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Ben the Ignorant

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About Ben the Ignorant

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    Proto Star

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  1. Meade ETX125 - How to remove front lens

    I just remembered I bought thermo-shrink tubes a long time after I made this tool, it would be more prudent to wrap the nail tips in that soft plastic, or a short piece of electrical wire skin would do, too.
  2. New Apo on the block

    It is never clipped unless a baffle is put at the wrong place, but never on purpose.
  3. Meade ETX125 - How to remove front lens

    Hi, other Ben. My C5 has that type of ring, I made this tool to unscrew it; just a slab of woob with two holes and two dull nails:
  4. out of collimation refractor?

    Hello, Joe. This is defocusing. Your stars look exactly like the extrafocal pattern of defocus: a tiny dot (purplish because the scope is a semi-apo doublet; in a full apo it's white) surrounded by a ring. This is the smallest pattern one can see outside of focus, when you defocus more the rings become more numerous. I see these patterns all the time when I use my achromat doublet. When defocused on the other side (intrafocal) the pattern is a bit different in the spread of colors but it's also a dot with rings that multiply when you defocus more. By the way, the minuscule pattern reveals poor alignment very, very strongly, and you just accidentally proved your doublet is absolutely perfectly aligned. Larger defocus makes the pattern much less accurate as a misalignment revelator. The field seems quite flat, too, the patterns in the corners are not shockingly larger or more oblong than those in the center. Aside from that very small defocus, your picture is excellent.
  5. Replacement aluminium focuser knobs?

    Wow, there's much more choice at Teleskop Austria! https://teleskop-austria.at/FokRad_Aluminium-Fokussier-Rad-einzeln-diverse-Modelle
  6. Replacement aluminium focuser knobs?

    You want aluminum; these are brass but they're not plastic: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p992_Orion-Elegante-Messing-Raeder-fuer-Okularauszuege---Set-2-Stueck.html
  7. Jet pass @ 80 fps

    The jet exhausts show as two blurred lines behind the plane, you need to look carefully, solar grain is less distinct there.
  8. Newbie: Advice on what to buy

    The 130 on EQ2 is more powerful and more stable.
  9. just saying hello

    Hi, Alan. Your neighbor is right about the cost of imaging in money and energy, better start visual only. But if you shop with strategy, the visual optics and mount can become an astrophoto rig; lots of imagers here will guide you. What kind of sky and scope do you have?
  10. Arrrgh.... Left Bhatinov on!

    Nice effect. Why not process it?
  11. Arrrgh.... Left Bhatinov on!

    Could you show the pics anyway?
  12. Trouble with Abberation

    Hi. You're overreacting, your pic is quite good. The little imperfection looks like a tiny bit of trailing but t's not coma. Just try without the coma corrector and you'll see: coma is nil in the center, and progressively worse toward the edges. It makes stars look like eggs, with the sharper part of the egg always oriented to the center. You're only assuming the problem is optical aberration, but it can't be, optical aberrations are never consistent over the whole field, only tracking error is.
  13. 240x with an 80mm triplet.
  14. What is the Maximum magnification you use (in UK)

    A bigger scope is like a better computer screen: smaller and brighter pixels, you see more even if the image has the same size. And when the core image can stand enlargement, you can do it without losing sharpness.
  15. Newbie: Advice on what to buy

    If you know it's a prejudice, ditch it! What you hated about that 60/900 was instability, not altaz motion or manual control. Dobs are wonderfully stable and accurate. Some of the current great values are: http://www.teleskop-spezialisten.de/shop/Teleskope/Dobson/bis-200mm/Bresser-Messier-5-Dobson-Newton-Reise-Teleskop-mit-Zubehoer::3461.html?MODsid=4d2cb30fcbd05cd694bb4df3989adca5 http://www.teleskop-spezialisten.de/shop/Teleskope/Dobson/bis-200mm/Bresser-Messier-6-Dobson-Newton-Reise-Teleskop-mit-Zubehoer::3462.html?MODsid=4d2cb30fcbd05cd694bb4df3989adca5 https://www.teleskop-express.de/shop/product_info.php/info/p7222_GSO-Dobson-Teleskop-150C---Oeffnung-6-Zoll-mit-hochwertigem-Crayford-Auszug.html And forget doing math with angles and setting circles, no one would keep their patience more than a few minutes with that method. Star-hopping is natural and very effective. You use it everytime you walk around or drive your car: you spot landmarks and orient yourself according to them; well star-hopping is the same except landmarks are dots, lines and figures in the sky. And just like you find many destinations by foot or by car without using maps or GPS, you'll soon know many destinations in the sky. Dob + star-hopping is the most natural way to travel the sky, just grab the scope and point it. Only binoculars are more immediate but they're another league. By the way, the GSO scope on sale at Teleskop Service has those tension springs that you can remove if you balance it carefully, up/down motion will be smoother. I've done it on my 20-kilos GSO 300mm tube, the benefit was obvious!