Used Takahashi Mewlon 250CRS w/ Built-In Corrector & Active Focus

  • Sale
  • $6,995.00
  • Regular price $9,420.00
  • Used Takahashi Mewlon 250CRS w/ Built-In Corrector & Active Focus

    • Sale
    • $6,995.00
    • Regular price $9,420.00
    • ITEM #

    • Sold Out



    • This is a used scope in excellent condition*
    • Corrected Mewlon design delivers flat field performance

    Used Takahashi Mewlon 250CRS w/ Built-In Corrector & Active Focus

    When Takahashi developed the correctors for their Mewlon line of telescopes it meant that any Mewlon-250 or 300 ever made could be converted into a flat field corrected telescope. This 3-element ED corrector allowed the Mewlon to be used as an imaging instrument or used as a corrected visual instrument capable of producing flat-field corrected views of the Moon, planets and deep space objects. The 250/300 Mewlons use an electric focus controller that moves the secondary mirror. Takahashi developed the secondary focusing system in 1990 and wanted to improve them with computer control. An ASCOM driver is available for download free from Takahashi Japan website.

    The CRS Mewlons are the product of this development. They both employ an ASCOM compliant driven secondary focusing motor that allows the Active Focus system to be controlled by an ASCOM compliant focusing system.

    Additionally, to make imaging easier a 3-fan cooling system is included. This system uses three sensors: one on the mirror, a second in the tube and a third outside to monitor and control the low vibration fans to bring the primary to ambient temperature. This can be done manually or controlled by an ASCOM compliant focusing program.

    The cooling system is controlled manually or automatically with the hand control. When the sensors read a difference in the temperature of the primary and ambient temperature the fans turn on and cool until the primary is brought to ambient.

    The provided hand control is used for manual focusing and cooling and as a connector for the computer controlled focusing program

    The USB port is used for the connection to the computer for auto focusing.

    The auto focusing system is called Active Focus. Active Focus includes a backlash revision function. The M-250CRS uses a four vane spider to support the pulse motor focusing system. It can be controlled with FocusMax, Maxim DL or similar software.

    The M-250CRS is an outstanding medium sized flat field imaging and visual instrument. It weighs 22lbs so it is portable and does not require a large mount to operate, so it can be easily transported to remote sites.

    A dedicated f/7.3 reducer and 1.5x extender are available optionally for added flexibility.

    A 7x50 illuminated reticle finder and tube holder are standard.

      Additional Information

      Aperture249 mm (9.8")
      Back Distance115.5mm
      Exterior ColorGloss White
      Finder Included7 x 50 Optical Finder
      Focal Ratiof/10
      Focuser ControllerIncluded
      Highest Useful Magnification600x
      Image Circle40mm
      Limiting Stellar Magnitude13.8
      Optical DesignKirkham
      OTA Length37.2"
      OTA Outer Diameter280mm
      OTA Weight26.4 lbs.
      Telescope SeriesTakahashi Mewlon
      Warranty Covered by OPT
    • Takahashi Mewlon 250CRS optical tube
    • Tube ring set and accessory bar
    • Active focus controller
    • 1.25" visual back/extension tube set
    • Lens cover
    • Original box and packing
    • * There is a 2" long scratch on the tube-see photo *

    Questions & Answers

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    • What additional items would I require, not already included with this telescope, to secure it to a Losmandy G11 GEM?

      You will need to get an Extra Large BT Tech Takahashi dovetail ( to fit the 125mm spacing on the bottom of the M250 rings. This plate is wide enough that you m

    • I have a Sky-Watcher AZ-EQ6 GT Mount. What would I need to attach the Mewlon 250CRS to that mount?

      The Mewlon 250 CRS uses tube rings w/ 125mm hole spacing, so you would need one of the BT tech XL dovetail plates to convert to Losmandy (D-series) format. The AZ-EQ6 comes with a dual saddle that accepts D-series plates, so the BT Tech plate for the Mew

    • I have a Celestron Advanced VX Mount. What would I need to attach the Mewlon 250CRS to that mount?

      While the base OTA weight is 26.4 lbs on the Mewlon 250CRS, once you add the rings, mounting plate, diagonal and eyepiece, you will be closer to 35+ lbs, which is too heavy for the AVX mount. I would suggest considering a larger mount for this scope or a