21 September 2023
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  • [ 11 September 2023 ] The Great Square of Pegasus: heralding autumn News
  • [ 18 August 2023 ] New comet predicted to brighten rapidly as it sprints Sunwards News
  • [ 2 August 2023 ] NASA picks up faint carrier signal from Voyager 2 News
  • [ 31 July 2023 ] Razor-sharp test images show Euclid’s instruments performing as expected News
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four-element

Equipment

3× four-element Barlow lens

12 May 2015 Steve Ringwood

Steve Ringwood investigates a 4-element, 3x Barlow lens that’s designed to provide efficient field correction and apochromatic performance that can match other highly specified optics in the light path.

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News Headlines

  • The Great Square of Pegasus: heralding autumn
    11 September 2023
  • New comet predicted to brighten rapidly as it sprints Sunwards
    18 August 2023
  • NASA picks up faint carrier signal from Voyager 2
    2 August 2023
  • Razor-sharp test images show Euclid’s instruments performing as expected
    31 July 2023
  • NASA loses touch with Voyager 2; waits for craft to ‘phone home’
    31 July 2023
  • Home
  • The Magazine
    • About
    • Current Issue
    • Subscribe
    • Renew Subscription
      • August last issue
      • September last issue
      • October last issue
  • AstroFest 2023
  • News
  • Observing
    • UK Sky Chart
    • Almanac
    • Scope Calc
    • DSLR Calc
  • Reviews
    • Equipment
    • Book Reviews
  • Spaceflight Now
  • Shop
  • Contact Us
    • Subscriptions
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    • Ask Astronomy Now
    • Editorial
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