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About Ruud

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    Free-Floating Planet

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    Thank you for visiting my profile. Besides astronomy, I take an interest in photography, skepticism, science, maths, podcasts, radio and cycling. I teach mathematics.
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    the Netherlands
  1. Ruud

    Sol 17-10-2018 Ha

    It's a wonderful golden arc of light! Beautiful
  2. Congratulations, Francis, and happy observing!
  3. Morpheus also has very little angular magnification distortion (AMD). Many eyepieces have positive AMD. Allowing positive AMD makes it easier for the designer to correct for astigmatism. Positive AMD means that the magnification of the eyepiece increases a few percent toward the edge of the field. Positive AMD has the effect of radially stretching out objects (like craters) at the edge of the field, making them look elongated. It also exacerbates pincushion and it inflates the apparent field of view of an eyepiece (at the same afov, with zero AMD the true field of view is larger than with positive AMD). Other eyepieces that have an AMD that is very close to zero are TV Delos, Ethos, and Nagler T4, and also Pentax XW. These eyepieces have a pleasing image geometry, which you notice when panning around in a dense star field, or when viewing the Moon.
  4. Is this your telescope? https://www.amazon.de/Celestron-AstroMaster-114-1000-Spiegelteleskop/dp/B0017WSP3E If so, There's nothing you can do about this problem. It's caused by the laws of physics (diffraction). A telescope with an aperture of D mm can only give useful magnifications up to 2*D times. For your telescope the limit is 228x. Magnification M = (focal length telescope / focal length eyepiece) * barlow factor. If the focal length of your telescope is 1000 mm, the eyepieces you mention will give these magnifications: 25mm without barlow: M = (1000 / 25) = 40x 25mm with 3x barlow: M = (1000 / 25) * 3 = 120x 9mm without barlow: M = (1000 / 9) = 111x 9mm with 3x barlow: M = (1000 / 9) * 3 = 333x 6mm without barlow M = (1000 / 6) = 167x 6mm with 3x barlow M = (1000 / 6) * 3 = 500x Above 228x, magnification becomes empty. The image gets larger but no more detail is revealed. Things just get blurry and dim.
  5. Sure. You have a lot of TeleVue eyepieces. Why not use the cleaning method they recommend? See here: http://www.televue.com/engine/TV3b_page.asp?id=103
  6. Ruud

    DSLR Hot Pixel

    My Canon has a "long exposure noise reduction" function that can be on / auto / off. It's in the menu "C.Fn II: image" Check for it in the manual of your 550D. In the setting auto, when you expose for more than one second, the camera takes an additional exposure of equal length with the shutter closed, right after the first, normal shot. It then subtracts the second (dark) exposure from the first, to remove the hot pixels. The time lapse looks wonderful.
  7. Ruud

    Eyepiece upgrade - TeleVue ?

    +1 for the Morpheus 17.5 Congratulations! I really love mine, and also the 6.5mm.
  8. Ruud

    Win 10 Fall Update

    I finally get it! We've been on Win 10 1803 since April, and every update since then has been for that. I wouldn't mind if Microsoft skipped Win 10 1809 altogether.
  9. Thanks, I'm downloading again.
  10. Ruud

    Win 10 Fall Update

    @Alien 13 I got confused Alan. I indeed thought you had the professional version because 1803 was the dreaded update of April this year. Haven't you had that laptop connected to the internet for the past half year? Anyway, the people who got into trouble this time (1809) were the ones who updated actively. They sent out a major bug warning over social media. Microsoft has responded by removing the feature part of the 1809 update and went on to just distribute the monthly security update. That was the little update we got last Tuesday (Wednesday for some) With Microsoft so eager to push out their buggy half-yearly feature updates, it is better not to actively seek out updates! Just let the automatic features run their course. That way you'll avoid being among the first to be unpleasantly surprised. Next time will be the April 2019 Windows Complaint season. I run O&O ShutUp10 after every update and block all safe-to-block spyware features of windows. A few weeks before the April and October updates I allow the telemetry, which I then turn off once more after the update is behind us. Like you, I just have the Windows Hone edition, so I cannot delay feature updates.
  11. Ruud

    Win 10 Fall Update

    I understand you can postpone feature updates for up to six months. I suppose you did that. Maybe those six months were over. I'll find the source for this and add it to this post. Edit: It was this:
  12. Wonderful, Bill, we always enjoy your reviews! The word DRAFT is printed across every page. Is that intentional? I'm going to read it anyway
  13. Ruud

    1.25" diagonal annoyances

    Well made, top performing diagonal prism: three surfaces must be flat, smooth and precisely oriented with respect to each other and the optical axis. The internal reflection will be total. There will be partial reflection when the beam enters and exits the prism. Light loss and ghosting must be minimized by having the first and last surface coated. The light has to travel through the glass. Dispersion must be low, the glass must be homogeneous in composition throughout and free of bubbles and other inclusions. Well made, top performing diagonal mirror: one surface must be flat, smooth and precisely oriented with respect the optical axis. The mirror must be coated. That's all. I would expect that for a diagonal prism to performs as well as a diagonal mirror, the prism would be much more expensive to make. I probably could not afford a prism of the same quality as my TV enhanced Aluminium or my WO dielectric mirrors. Between these two, btw, I see no difference in image quality.
  14. Ruud

    Mars, September 2018

    Oh dear, you did it again. That's excellent!
  15. Ruud

    1.25" diagonal annoyances

    Hi, you could consider replacing them with longer screws (ones that have a long, thin knob at the end rather than a short, wide one). Diagonals collect a lot of dust etcetera, so they need regular cleaning. Dielectric mirrors are very hard, which makes them easy to clean without having to be too careful. That's why I prefer them.

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